The following are comments by Douglas J. Hughes, ISASI MO4415, retired aerospace accident investigator, on the FAA’s request for comments regarding EMI in aircraft

 

Ann Arbor, Michigan, USA
October 12, 2012

SUBJECT

Passenger Use of Portable Electronic Devices on Board Aircraft Notice of policy; request for comments (RFC)

SUMMARY OF COMMENTS

• Air travel is tedious.  The use of personal Portable Electronic Devices (PEDs) by passengers is common and helps to reduce the tedium and increase efficiency of the business traveler.
• Aircraft safety requires diligence at all levels, many of which are beyond the control of aircraft operators.
• Passengers play a key role in aircraft safety and need to know the basics.
• Passengers often feel they are more knowledgeable than the experts with respect to aircraft safety.  A paradigm shift is required.
• Historical data suggest that passenger use of personal PEDs has had negative impacts on aircraft safety that were beyond the control of the operators.
• Passengers often feel they are more knowledgeable than the experts with respect to PED use on board.  A paradigm shift is required.
• The Federal Aviation Administration (FAA) of the US Department of Transportation (DoT) implemented simple-to-follow guidance on use of PEDs on board aircraft a half century ago that has improved air safety by implanting the “Please-Turn-Off” announcement in the consciousness of all passengers.
• The FAA plays a key role in USA air travel safety and represents the public interests.
• Electromagnetic Interference (EMI) happens.
• The FAA is to be commended for plans to establish an Aviation Rulemaking Committee (ARC) to review technology advances that can lead to safer and expanded PED use on board during all ground and flight phases.  The ARC effectiveness can be enhanced by membership beyond that of regulators, manufacturers, and operators.  ARC effectiveness can also be enhanced by knowledge of passenger PED histories.
• PED batteries are a potential smoke-in-the-cabin or even fire safety hazard.
• Limit federalism of PED-use safety oversight to public interest issues.  Expand the FAA public education role with respect to safe PED use.
• Data strongly suggest that passenger PED use has contributed to aircraft incidents and accidents.
• The air safety investigation community in the USA is often not well equipped to investigate EMI as a possible accident/incident cause.
• Consider leaving the existing policies in place.

 

GLOSSARY

                              AD      Airworthiness Directive

ARC      Aviation Rulemaking Committee

ASRS      Air Safety Reporting System

ATC      Air Traffic Control

A/A      American Airlines

CFIT      Controlled Flight Into Terrain

CNI      Communications, Navigation, and Identification

CSEL      Combat Survivor Evader Locator

DoD      Department of Defense, Executive Branch, United States of

America (USA)

DoT      Department of Transportation, Executive Branch, USA

DSP      Digital Signal Processing

E3      Electromagnetic Environmental Effects

EMI      Electromagnetic Interference

ETEB      Engineering Test and Evaluation Board (of the FAA)

FAA      Federal Aviation Administration

FCC      Federal Communications Commission

GSM      Global System for Mobile communications

HIRF      High-Intensity Radiated Fields

IEEE      Institute of Electrical and Electronic Engineers

IIC      Investigator In Charge

ILS      Instrument Landing System

IPL      Interference Path Loss

ISASI      International Society of Air Safety Investigators

MHz      MegaHertz (a unit of frequency)

NASA      National Aeronautics and Space Agency

NTSB      National Transportation Safety Board of the USA

PCU      Power Control Unit

PED(s)      Portable Electronic Device(s)

RFC      Request for Comments

SC      Special Committee

SMS      Safety Management Systems

T-PED      Transmitting PED

TDMA      Time-Division Multiple Access

TV      Television

US Air      US Airlines

USA      United States of America

USAF      United States Air Force

WG-3      Working Group 3 (of RTCA SC-202)

EXPANDED COMMENTS

 

Perspective

The following comments are respectfully submitted by a retired professional air safety investigator who specialized in Electromagnetic Environmental Effects (E3).  I am one of the few investigators who practiced this unique expertise.  The submitter is of the belief, based on two decades of professional involvement and study[1], that any discussion of PED use on board aircraft must consider the related subjects of aircraft safety and EMI.  The subject RFC concentrates mostly on policy decisions, but avoiding discussion of EMI impacts to safety would be imprudent.

The submitter’s pre-retirement professional profile may be viewed at:  http://www.emcs.org/acstrial/newsletters/fall04/personality.html

Some “Preaching-To-The-Choir” Comments With Respect To Air Safety

Every aircraft incident or accident is a painful learning experience.  Over time, and many hard-learned lessons, general and commercial aviation have become safer.  The participants in the safety process are:

1. The Regulators
1. International
2. National
2. Traffic Control
1. Ground
2. Approach/Departure
3. En-Route
3. The Aircraft Manufacturers
1. Airframe
2. Suppliers
4. The Operators
1. Management
2. Maintenance
3. Scheduling
4. Ground Operations
5. Flight Crew

1.                                                               i.      Flight Deck
2.                                                             ii.      Cabin

5. The Passengers
6. The Air Safety Investigators

Participants at level 6 are involved as last resorts whenever those at the higher five levels allow holes in Reason’s Swiss-Cheese Model (Figure 1) to align.

 

Figure 1.  James Reason’s Swiss Cheese Model

Participants at levels 1 through 4 practice regimented Safety Management Systems (SMS) to the great benefit of the flying public.

The passenger group making up level 5 is the subject of this RFC due to the issue of PED use on board.  Passengers know and practice most of the basic safety rules.  Exceptions result in injuries, such as when they fail to fasten seat belts during turbulence and end up hitting the overhead storage bins.  They can also respond efficiently during an emergency as demonstrated January 15, 2009 when US Airways Flight 1549 had to land in the Hudson River after multiple bird strikes.  All 155 crew and passengers survived with few injuries.

Passengers and PEDs

Few seem aware of the history and seriousness of the subject.  Rather than obtain, digest, and research large technical reports from FAA/RTCA[2]^{, [3], [4], [5]}/NASA[6]^{, [7]}/DoD/Graduate Degree Theses[8]^{, [9]}/etc., they get their data from bloggers such as Nick Bilton and Christine Negroni, or entertainment television (TV) shows such as Myth Busters.

The consensus opinions of the subject by passengers appear to be:

• A myth promulgated by the FAA for five decades
• Has no basis in science
• Baseless rule
• Pilots use them, so why can’t we?
• The flight attendant role isn’t safety, it’s service to the passenger, and they are removing a service
• There have been no fatalities, so PEDs are safe to use on board

 

Media Attention

Long gone is the “Woodward and Bernstein”-era of investigative journalism.  Now 800-word articles, 30-second sound bites, and blogs set the tone for media.  Passenger PED use is a favorite subject for “instant journalism” since the audience all think they are experts, they will read/watch, they often give feedback, and the reporter can edit to fit the available space.    What is sacrificed is often fact, since PED-use issues are quite technical.  The reporter does not want to “hurt the head” of the reader/watcher.  Technical content is often heavily edited or removed.

However, there have been some media reports worthy of examination by the ARC if formed:

• The West Wing, Pilot, First Scene.[10]  Although this was not generated by a reporter, it represents the opinion of influential and Emmy- and Oscar-winning screen play writer Aaron Sorkin.  The Toby Ziegler character Sorkin created gives the impression he knows far more about aircraft design than anyone else, especially the poor flight attendant.  Many seat mates also share this opinion.  Just ask.
• Can My iPod Make This Airplane Explode?  GIZMODO, December 7, 2009.[11]  This is an excellent example of uninformed blog reporting.  One paragraph heading was “The EMI Lie”.  Passengers read junk like this and immediately become experts on the PEDs subject (Am I repeating myself?).  However, the GIZMODO author got some great feedback from flight crew members who pointed out just how wrong he was.  One early reply was “Well, that pretty much settles that.  I had no idea pilots have personally witnessed this level of interference.”
• Interfering With Flight?  New York Times, January 17, 2011.[12]  I was quoted with respect to generational advances for both aircraft and PEDs.  Christine’s article was shortened by the NYT editorial staff.  She got a lot of feedback, and other media types almost immediately attempted to follow her story with their own.  I got calls and electronic mails.  One reporter in England plagiarized Christine.  The New York Times legal staff responded.  Christine was also interviewed on MSNBC.[13]
• Cellphone Use on Planes Safety Threat?  ABC News, June 9, 2011.[14]  This was wrongly titled as it dealt with all PEDs, not just cellular telephones.  Boeing’s David Carson did well on camera.  Radiated emissions from three popular PEDs were displayed on camera as measured by Bruce Donham’s team in Boeing’s shielded lab.  All three had spurious emissions above Part 15 limits in the bands of interest.
• Can Mobile Devices Really Interfere With A Plane?  NBC Nightly News, October 10, 2011.[15]  This well-produced 2-1/2 minute report packs a lot into a short period.  Boeing’s Bruce Donham and David Carson point out the danger is not just emissions from transmitting PEDs (T-PEDs) but from PED in-circuit clocks and oscillators that sometimes are poorly shielded and allowed to radiate.  Please watch this one.
• Many fliers refuse to turn off electronic gadgets.  USA Today Front Page, December 21, 2011.[16]  This was an extensive report following the Alec Baldwin December 6, 2011 removal from an American Airlines (A/A) flight for failure to turn off the on-line game “Words with Friends” when asked to do so.  I was quoted with respect to EMI being “an undetected factor in some airline crashes.”  Keep reading folks, as I have much more to write on this subject.  Stoller’s first question, like every other reporter who has called, was about accidents.  This is called “The Tombstone Mentality” in the air safety community.
• Editorial:  Fliers, think before turning on electronics.  USA Today, December 21, 2011.[17]  This editorial admits that the “Alec Baldwin” story was addressed by their reporters as bogus concerning the FAA PEDs safety announcement.  It goes on to discuss their change of opinions after reviewing extensive data, evidence, and multiple interviews.
• 10 Facts about Portable Electronics and Airplanes.  Scientific American, December 22, 2011.[18]  This article contains the FAA press release following the December 6, 2011 “Alec Baldwin” A/A episode.  This one article addressed many of the policy and technical issues introduced by the subject RFC and should be required reading for the entire FAA staff and ARC members.
• Is Using Devices on Planes Really Dangerous?  CBS News, January 27, 2012.[19]  This was extremely well done and again shows David Carson from Boeing.  Captain “Sully” even had a great on-camera statement about irresponsible passengers who conduct unauthorized safety tests on board.  Reader – please use the URL below to watch this one.
• What’s In Your Wallet?  Capital One Venture Card television commercial viewed by tens of millions during NBC’s coverage of the London Olympics.  The last seconds of this commercial includes one of the most positive endorsements of the FAA PED safety rule yet seen.  Norseman:  “Can you play games on your phone?”  Alec Baldwin:  “Not on the runway – nooooo.”  That guy can act.  It almost made me want to get one of their credit cards.  This classic commercial has yet to appear on youtube.com.

Some EMI Techno-Nerd Material

This commenter and USA Today reporter Gary Stoller exchanged a series of electronic mails and telephone conversations during December 2011 while Stoller was developing his story.  One I sent had the following summary of how the various RTCA and NASA studies divided up the technical EMI issues.  This material was too detailed to survive the USA Today editor.

RFC-Specific Comments

 

The FAA seeks comments on current policy, guidance, and procedures that aircraft operators (ranging from pilots of general aviation aircraft up to and including air carrier certificate holders at the major airlines) use when determining if passenger use of portable electronic devices (PEDs) may be allowed during any phase of flight on their aircraft.

This commenter has consulted to both Part 91 and USA Department of Defense (DoD) aircraft operators.  I am not a pilot.  However, my extensive comments might be of interest and educational.

Once all the comments have been collected, the FAA intends to establish an Aviation Rulemaking Committee (ARC) to review the comments and provide recommendations that might permit the more widespread use of PEDs during flight while maintaining the highest levels of safety for the passengers and aircraft.

The ARC idea is commendable and should be repeated periodically (every four or five years) as technology advances.  The ARC should include membership broader than just the operators, manufacturers, and regulators.

In response to those comments, the FAA concluded that the aircraft operators were best suited to make the determination of which PEDs would not cause interference with the navigation or communication system on their aircraft. The FAA also recognized that for it to place requirements upon itself to conduct or verify tests of every conceivable PED, as an alternative to a determination made by the operator, would thereby place an excessive and unnecessary burden on the agency.

Agreed.  Also the FAA has to consider possible federal budget cuts.  One may be hitting January 3, 2013.

Many of these aircraft using this older technology are still in service and are as susceptible today to interference as they were when they first entered service.

Unfortunately, very few passengers understand this point, although pilots do.  I make a point of viewing the builder’s plate as I walk through the cabin door upon boarding a commercial flight.  The flight attendants often ask why.  I briefly tell them.  I’m an abnormal passenger.

The FAA defined requirements for high-intensity radiated fields (HIRF) that provide assurance that newer aircraft with such systems have sufficient protection to continue to operate safely when exposed to spurious emissions of PEDs and intentional transmissions from transmitting PEDs.  While the highly critical fly-by-wire controls and electronic displays were designed and certified to withstand the fields from transmitting PEDs, all aircraft electrical and electronic systems were not designed to withstand these fields.

The ARC members are encouraged to study the issue of HIRF certification and “grandfathered” aircraft systems/subsystems that are allowed to be used without being HIRF tested.  Great progress has been made in aircraft “hardening” to HIRF within the past two decades.  This was one of my focus areas during a 42-year career as an E3 engineer.  Appendix A is an extensive list of HIRF research references and is included with this set of comments to aid the ARC in learning the background and progress in HIRF protection.  The reader may observe the changes that occurred about two decades ago.  The latest research (by NASA/Langley) has shown that aircraft flight controls can be designed such that HIRF EMI is adaptively filtered resulting in safety improvement.  This commenter agrees that an aircraft certified to current HIRF requirements should NOT suffer back-door EMI from T-PEDs.  There are always exceptions however.

Study of multitudes of aircraft upsets due to E3 has revealed that a majority involve flight control systems incorporating analog feed-back loops.[20]  Many are included in the Appendix A reference list.  These feed-back loops often supply control surface, or other flight or engine control, position data to flight-direction computers.  Electrical noise (EMI), coupled to such feed-back loops, is interpreted as an incorrect position requiring correction.  Incorrect flight control changes result in upsets.  Some have had fatal consequences.  Many case histories have been collected into the Reference 20 technical “lessons-learned” presentation given multiple times by this commenter.  I am available to brief the ARC if desired.

These newer aircraft still have sensitive navigation, communication, and surveillance radio receivers that may be susceptible at certain frequencies to spurious radio frequency emissions from PEDs.

This commenter agrees.  This commenter is also of the opinion that PED-use policy changes must be made after serious, adult, no-conflict-of-interest, study.  A complication is that aircraft CNI signal formats are ancient.  The instrument landing system (ILS) formats have a maturity of over 60 years.  ILS receiver detectors can be (and have been) made digital signal processing (DSP) adaptive to filter EMI, but one of the manufacturer representatives serving on RTCA Special Committee 202 (SC-202) admitted that ILS receiver design has progressed to the limit due to the ancient signal formats.  Only on-board sampling of the on-board EMI environment can possibly improve the adaptive features of sensitive CNI receivers.

Flight-deck crew members are often expert at recognizing EMI events and having cabin crews search for passengers PED use and correlation.  The data are extensive.  Appendix B is included in these comments as representative.  A crew of an older “Classic” (stinky!) Boeing 737 recognized an EMI event and commented about the differences in these events experienced in the older versus the newer “Glass-Cockpit” aircraft.  Appendix B is from the anonymous NASA Air Safety Reporting System (ASRS).  The ASRS contains many similar reports.

Most portable electronic devices have internet connectivity that includes transmitting and receiving signals wirelessly using radio waves, such as Wi-Fi, Bluetooth, and various other cellular technologies.  These devices transmit high-powered emissions and can generate spurious signals at undesired frequencies, particularly if the device is damaged.

Keeping track of devices will require a full-time staff by the operators since the available PEDs change weekly.  As this commenter is sitting here typing, another half million iPhone 5’s are being sold.  Asking the cabin crew to monitor these devices is “not in their pay grade.”  Any RFC replies submitted by the cabin crew unions should be treated with extreme seriousness.

As such, harmful interference from PEDs cannot be tolerated.

This is a statement of the obvious.  Harmful interference is never a good thing.

The FAA provides oversight of aircraft operators to ensure that they have established and are currently following robust PED-allowance procedures.

Please never relinquish this oversight role.  I pay FAA staff salaries every April 15^th.  I pay the aircraft operators’ salaries rarely.  We passengers place considerable trust in the FAA.  The FAA represents the USA passenger public interests.

1) Procedures and methods for operators to allow the use of PEDs.

 

• What processes and methods are aircraft operators currently using to evaluate PED technology interference?

This commenter has consulted to Part 91 and DoD operators and knows that Interference Path Loss (IPL) analyses and measurements, subsystem EMI susceptibilities, cabin EMI mapping, ground testing, flight testing, crew feedback, and other methods are being used.

• How can those procedures and methods be improved?

They can be repeated whenever fleets are updated and modified.

• Is additional FAA guidance and policy needed?

Yes!

One concept is for operators to improve the sharing of test and compatibility data, so that the same compatibility testing could be leveraged to support many aircraft operators.

Operator test and compatibility data could be interpreted as work product and intellectual property.  If so, the ARC membership will include attorneys.  Just saying!!!

Data concerning PED and aircraft compatibility could be used by the operators to analyze incidents involving PED interference.

• Should the industry develop data sharing for this purpose?

Yes!

2) Reliability of aircraft systems. Future aircraft could be manufactured to be immune to the PED environment.

This interesting sentence may be interpreted as either an unsupported conclusion or FAA position.  Either interpretation is inappropriate for inclusion in a RFC.  Is the sentence correctly worded?

• Is it necessary to establish aircraft certification regulations to require new aircraft to be PED-tolerant?

It certainly appears to be a great idea (motherhood and apple pie).

In addition, many aircraft systems have already qualified for operation in high intensity radiated field environments.

• How can these demonstrations best be leveraged to help an operator allow the use of PEDs?

By careful review of the aircraft interface wiring diagrams to discover any flight-critical electrical or electronic analog feed-back loops.  Efficient initial investigations should (must?) concentrate on grandfathered systems/subsystems.  Once found, EMC specialists should (must?) make sure the loops are HIRF hardened.  Then operators should (must?) concentrate on the digital feed-back loops and make sure they are also hardened, maintained, and include error-correction coding.  This is about a two-day job per aircraft series for an experienced aircraft E3 specialist, if one can be found.  The job should (must?) be repeated for each and every aircraft update and/or configuration change.  Wire maintenance, especially shielding, is a long-term effort.

 

3) Aircraft Immunity to PED Interference. Some aircraft manufacturers and avionics equipment manufacturers have already demonstrated PED and aircraft system compatibility.

• Should aircraft manufacturers and avionics equipment manufacturers provide documentation of aircraft PED tolerance, aircraft systems that meet RF susceptibility requirements, interference path loss, etc., to the operators to support the operator’s PED allowance determination?
• Should it be mandatory that aircraft manufacturers and modifiers provide this information to the operators for new and modified aircraft?

Yes to both queries, if the financial and legal issues can be resolved.

4) Promote aircraft-compatible PED transmissions. The transmissions from PEDs vary widely, making it very difficult for an aircraft operator to discriminate between PEDs that may be acceptable and those that may not.

• Could the consumer electronics industry develop standards for aircraft-friendly PEDs, or aircraft-compatible modes of operation, that would reduce the risk of interference to aircraft systems by defining maximum emissions in designated bands?

Those of us following this issue realize that T-PEDs do not have intentional radiation in aircraft CNI frequency bands.  It is the unintentional spurious emissions from the PEDs that appear in the bands of interest.  The Federal Communications Commission (FCC) Part 15 limits restrict the levels of these spurious emissions.  However, PEDs with spurious emissions meeting Part 15 in the CNI bands can still exceed CNI receiver degradation thresholds from certain aircraft passenger and crew seats with minimum IPLs.  The RTCA reports (References 4 and 5) present more detail with respect to the adequacy of Part 15 limits.

The commenter was a member of both RTCA SC-177 and SC-202.  During one SC-177 meeting, I tried to discuss this issue with a representative of the consumer electronics industry, a lobbyist, who replied that their devices have no spurious emissions.  I guess he was paid to say that.

The better question should have been “Will the consumer electronics industry ….?”

The ARC may wish to open “Pandora’s Box” and suggest different seat colors for those with IPLs less than the minimum.  A map placed in the seat-back, showing those critical seats, is another alternative.  Let the flight attendants be the cops since they have so few other duties (sorry, written in irony – I’m awaiting the flight attendant unions comments in response to this RFC – we can guess that they won’t be pleased).

IPL is easily predicted using the methods of Reference 4, Paragraph 3.6.  The prediction methods have been validated with a multitude of measurements.  Again, see Reference 4.  Some seats are very close to CNI antennas.

The ARC will have their hands full with this issue.  However, it would be a great passenger service to allow PED use during long taxi times.  Just be sure the PED spurious emissions are not in the flight crew communications bands (118-136 MHz).

Air Traffic Control (ATC) communications are critical during taxi at busy airports.  Some taxiways cross active runways.  The pilot not taxiing can always get the passengers’ attention by going on the public address system to request passengers at window seats in rows 4 through 12 (for example) to please turn off their jammer devices so that they can hear the tower through the buzzing EMI.

Hey readers, passenger PED use IS a safety issue.  Myth Busters should have called me for their show.

 

5) Passenger perspectives on use of PEDs. Increased access and usage of PEDs may distract passengers during crewmember safety briefings and instructions. In addition, PED usage may have an adverse impact on flight and cabin crew responsibilities and duties. In 2005, the FCC solicited comments on the potential to expand the use of cellular phones in flight and received responses from passengers concerned about the use of cell phones by other passengers. One of the main concerns expressed by the public comment was the fear of passenger disruptions caused by cell phone use in a crowded public conveyance.

• If some PEDs are found to be compatible with aircraft systems, should there be restrictions on the use of PEDs for other reasons?
• Should voice communications using other technologies such as voice over IP be limited or restricted?
• Should aircraft operators be required to publish their PED policies?

First Bullet – The sterile cabin rule for landing should remain for safety reasons.

Second Bullet – Voice Over IP and Video (Skype).  The ARC should seriously consider allowing these services on flights equipped with wireless internet access.  The use of microphone-headset devices should be encouraged for both the privacy of the passenger communications and as a courtesy to seat mates.

Third Bullet – It should be voluntary.  BTW, I’ll avoid flights on any operator airline that refuses to publish their policies.  The customer is always right, and we control the market!

 

6) PED article retention risk considerations.

The sterile cabin rule for landing should remain for safety reasons.

7) Active monitoring for harmful interference. A handheld device or installed system could be used by the crewmembers to detect harmful interference from PEDs. This could allow the crewmembers to identify problems and instruct passengers to disable devices when they generate harmful signals.

• Should the FAA consider working with industry to develop standards for an active PED monitoring system?

This commenter is a retired electronics engineer and considers this the most interesting technical question contained in the RFC.

I “vote” yes.

However —-

Any such system will suffer from high false alarm rates unless it is integrated with the aircraft flight management system (tuned to the CNI frequency being used by the flight-deck crew) and has sensor antennas located adjacent, but internal, to the external CNI antenna being used by the flight management system.  Without proper sensor antenna placement, the IPL issues will not be equivalent.

Once a PED monitoring system is developed, the obvious next step is to have the system adaptively feed the CNI receiver detectors to allow DSP EMI cancellation.

The comments above apply to front-door EMI.

Back-door EMI sources will be easier to detect since T-PEDs, like my ham radio handy talkie, are higher power devices.  (I’ll never turn it on while an aircraft passenger.)  Back-door PED detectors will have to be distributed throughout the passenger area and monitor more than just the CNI frequencies.  A simple envelope detector might work.  Again, such a detector will have high false alarm rates complicating flight-deck and cabin crew workloads.

This might be an interesting project for a FAA staff member or two.  The end stages will include a lot of frustration tracking down false alarms.  Cabin crews will hate these detectors especially if they have to carry them.

Wouldn’t it be much easier to just keep the current restrictions?

 

8) Technical Challenges. and 9) Operational Challenges.

The ARC needs to understand the complex histories to avoid repeating mistakes and some misunderstood safety issues.  Battery over heating as a safety issue is a special interest area that needs to be addressed by the ARC.  See the following expanded discussion.

 

Is Passenger Use Of PEDs A Safety Issue?

This is the key issue for review by the ARC prior to any FAA policy changes.  Those favoring expanded use have valid issues.  WiFi on board has been available in the USA for several years and is used on the newer “hardened” aircraft with few reported EMI events.  The safety issues mainly concern over-heated PED batteries and older, non hardened, aircraft.

There are still some PED events reported to the anonymous NASA ASRS.  A set of the most recent 50 PED reports may be downloaded at http://asrs.arc.nasa.gov/docs/rpsts/ped.pdf.  Sets from decades ago showed more frequent events, which may imply less emission from PEDs and better hardening of the aircraft.  Things appear to be slightly better.  That’s not good enough folks!

But even the latest ASRS PEDs set reports the following 16 apparent EMI episodes (dated from July 2002 to May 2011) that the ARC should study:

ACN: 950259 (2 of 50)

Synopsis

CRJ200 First Officer reports compass system malfunctions during initial climb.

When passengers are asked to verify that all electronic devices are turned off the

compass system returns to normal.

ACN: 754696 (10 of 50)

Synopsis

IN AN APPARENT PED INTERFERENCE EVENT, A PAX’S PORTABLE GARMIN GPS

MODEL NUVI 660 ALLEGEDLY INTEFERED WITH A B737 CLASSIC’S (NO GLASS)

DME NAVIGATION UPDATE FUNCTION.

(See Appendix B for the full text)

ACN: 702630 (18 of 50)

Synopsis

CAPT OF AN A320 RPTS VHF INTERFERENCE ON ZOB ARTCC FREQ FROM A CELL

PHONE ABOARD HIS PLANE.

ACN: 681689 (20 of 50)

Synopsis

A B757-200’S L FUEL GAUGE BLANKED AFTER TKOF AND BECAME OPERABLE

PRIOR TO LNDG. CREW SUSPECTS POSSIBLE PED INTERFERENCE.

ACN: 673795 (21 of 50)

Synopsis

B737-800 FLT CREW EXPERIENCED SEVERAL TCAS RA’S ALLEGEDLY GENERATED

BY A WI-FI ENABLED LAPTOP COMPUTER.

ACN: 661013 (22 of 50)

Synopsis

FLT CREW OF CRJ-700 RPTS THAT AURAL INTERFERENCE IN VHF COMS CEASED

WHEN PAX WERE ASKED TO ENSURE ALL FORMS OF 2-WAY COMS WERE TURNED

OFF.

ACN: 619593 (26 of 50)

Synopsis

A B737-700 AUTOPLT GOES INTO CTL WHEEL STEERING MODE DURING AN ILSLOC

COURSE INTERCEPTION. FLT CREW EXPERIENCES A HDG TRACK DEV AND A

MISSED APCH FROM SCT CTLR 9 MI W OF BUR, CA.

ACN: 611910 (30 of 50)

Synopsis

DISPLACED LOC AND GS COURSE CREATES A HDG TRACK DEV BY THE FLT CREW

OF AN MD80 ON APCH TO RWY 2 VISUAL WITH ILS BACK UP DURING A NIGHT OP

AT BNA, TN.

ACN: 609264 (31 of 50)

Synopsis

B737-300 CREW HAD ERRATIC LOC SIGNALS ON ILS RWY 13 AND RWY 7 AT JAX.

A PAX WAS USING A ‘PALM PILOT’ AT THE TIME.

ACN: 600964 (34 of 50)

Synopsis

FLT CREW OF MD80 EXPERIENCE MISALIGNED HEADING INFO ON FMS DISPLAY.

SUSPECT PAX OPERATED ELECTRONIC DEVICES.

ACN: 597486 (36 of 50)

Synopsis

A FALSE TCASII RA SENDS A DC9 FLT INTO A CLB TO AVOID A POTENTIAL TARGET

5 MI SE OF BUNTS INTXN, PA.

ACN: 579608 (40 of 50)

Synopsis

DC-9 FLT CREW RECEIVED A FALSE TCAS RA DURING DEP CLIMB AND INCREASED

THEIR RATE OF CLB TO AVOID A FALSE TARGET APPARENTLY GENERATED BY A

PAX LAPTOP COMPUTER.

ACN: 576709 (41 of 50)

Synopsis

AN ACR B737-700 CREW, ON APCH TO BWI RWY 10, ATTRIBUTES BEING OFF

COURSE TO POSSIBLE UNAUTH USE OF CELL PHONES PROMPTED BY A CABIN

ANNOUNCEMENT. THE INABILITY OF THE CREW TO BOTH BE ON THE ILS FREQ

BECAUSE OF THE APCH DESIGN, ALSO MAYBE A CONTRIBUTING FACTOR.

ACN: 576147 (42 of 50)

Synopsis

MD88 CREW HAS STATIC ON THE #1 VHF COM RADIO. THE STATIC STOPPED

WHEN THE PAX WERE DIRECTED TO TURN OFF THEIR ELECTRONIC DEVICES.

ACN: 557959 (46 of 50)

Synopsis

A B727-200 CREW, ON INTERCEPT HDG FOR AN ILS TO ATL, EXPERIENCED

IRREGULAR LOC DEFLECTIONS ON THE CAPT’S CDI, RESULTING IN A CORRECTIVE

VECTOR FROM ATC.

ACN: 555344 (47 of 50)

Synopsis

A B767 HAS MULTIPLE ELECTRICAL SYSTEM MALFUNCTIONS INCLUDING LOSS OF

ENG AND FLT INSTRUMENTS AS WELL AS CTL OF AUTO FLT SYSTEMS FOR A

SHORT PERIOD OF TIME DURING CRUISE FLT.

 

The EMI-Suspicious Accidents & Incidents and Investigation Inconsistency

After serving on both RTCA SC-177 in the 1990’s and SC-202 in the 2000’s, my name is out there.  I get calls from reporters.  All want to know if PED use has caused accidents.

After I give them the well-known Christchurch story, they want more.  I then refer them to Bill Strauss’ thesis, Reference 9, which has an interesting approach to the accident issue.  It is doubtful that they read long documents, but I suggest they do so anyway.

They then want more.  A successful approach I’ve employed is to give them a challenge, such as “use your investigative reporter skills to research flight such-and-such and prove to me that it WASN’T due to passenger PED use”.  I’ve collected a large list over the years, which I’ve condensed to Table 1.

EMI INVESTIGATED	EMI NOT INVESTIGATED
• Operation Aphrodite	• KAL 007
• CVN-59 Forrestal Fire	• Lauda Air
• TWA 266/United 826 Midair	• Crossair CRX498
• F-4 Nose Gear Steering	• Carnahan Cessna 335
• Fuji Airship	• Tg261
• A/A 587	• A/A 1340*
• IFO 21	• Air Transit 961*
• TWA 800	• United 585
• Swiss Air 111	• US Air 427
• Egypt Air 990
• Operation Provide Comfort F-15/UH-60 Fratricide
• Quantas Flight 72	Note:
• Piper PA 31-350 ZK-NCA Christchurch, NZ	* EMI Improperly Investigated
• RQ-4A S/N 2
• KAL 801
• F-4 Aileron-Rudder Interconnect
• UH-60 Blackhawk Pitch Upsets
• A/A 1291
• Thai Airways International fuel tank explosion 3/3/01 at Bangkok

 

Table 1.  EMI-Suspicious Aircraft Incidents and Accidents

When the reporters realize work is involved, they change the subject or get frustrated with me as a source and go away.

Many of the print news journalists are going away due to their newspapers folding.

This a great place to insert my RTCA PEDs SC experiences.  It explains a little of what follows.

SC-177 was originally formed due to a Lansing, MI congressman insertion of a paragraph in the FAA funding bill (some year in the early 1990’s) requiring resolution of the “cellular-telephone-use-on-board” issue.  The congressman had run afoul of a flight attendant while using a cellular while his flight airplane was at the gate.

SC-177 had huge membership and activity until everyone realized that cellular telephone use on board was not in the purview of the FAA, but rather the FCC.  RTCA serves the FAA not the FCC.  A representative from the FCC finally showed up and stated there was no way they’d change their policy.  It is to protect the ground cellular network from saturation and delay equalization issues.

Most of the SC-177 members walked out of the room and never returned.  They were from the cellular telephone industry and followed the FCC guy out the door.

The rest of the SC-177 efforts dealt with use of non-cellular PEDs, taking extensive (and excellent) IPL measurements, taking extensive (and excellent) PED spurious emissions data, formalizing test methods, and concluding, yet again, that PEDs used on board was a safety threat.

I was working for a large engineering consulting firm that worked mostly on DoD E3 and radio spectrum issues.  The FAA tasked me with discerning if the four EMI levels (source, coupling, victim, & degradation) can be predicted for PEDs used on board aircraft.

My task ended with success.  I showed that all four levels could be predicted using relatively simple, and DoD validated, algorithms.  The work is referenced, but not included, in Paragraph 3.6 of Reference 4.  My 53-page report is available from the FAA ASR-1 or from me – I kept a copy.

The issue of passenger PED use leading to accidents was brought to the table by a SC-177 member from US Airlines, shortly after their USAir 427 September 1994 fatal rudder roll on approach to Pittsburgh, and was quickly tabled.  The members feared the subject.

SC-202 addressed the wireless (WiFi, etc.) PEDs-on-board issue and was a well-run committee (unlike SC-177 – enough said).  I ended up being cochairman of Working Group 3 (WG-3), Aircraft Susceptibility.  My effort with SC-202 was funded by the United States Air Force (USAF) in order to gain additional data and expertise leading to a cockpit safety analysis and test of a newly developed Combat Survivor Evader Locator (CSEL) system.  This effort also ended with success.[21]^{, [22]}

The subject of PED use leading to accidents was also brought up in SC-202 by the cochairman of WG-3 – me.  I was later approached in the hall and encouraged to drop the subject, but I did not.  Two major aircraft manufacturers (Boeing and AirBus) were members of SC-202, but they would not participate in WG-3.  One would think they would be the experts for aircraft EMI susceptibility!  I had to go out and recruit WG-3 members and found some great support.  Representatives from two of the major regional jet manufacturers participated including the author of Reference 8.

Many of the incidents and accidents listed in Table 1 were researched by SC-202 WG-3.  Extensive data were discovered.  Data are available from this commenter upon request.  Several findings are summarized in Reference 20.

It was discovered that the air safety investigation community (Level 6 in the safety process as listed above) is inconsistent in their approaches to investigation of EMI as a possible contributing factor in aircraft incidents and accidents.  Most are quite good, but there is room for improvement.

A few examples from Table 1 might be of educational interest to the readers and ARC.

KAL 007  The flight-deck crew was way off course.  The inertial navigation systems would not have suffered that much drift.  Was there EMI to the radio navigation receivers?  SC-202 WG-3 did not open this can of worms.  This one is a favorite of the conspiracy theorists.

Lauda Air  This tragic mid-air thrust reversal of a PW-4000 engine was discussed in Reference 8.  SC-202 WG-3 did some digging on this one.  It was NOT caused by passenger PED use.

Crossair CRX498  The March 2001 SAFETY IN AVIONICS column in AVIONICS magazine stated that mobile phone use was causal for this accident.  David Evans usually did careful research for his columns.

Carnahan Cessna 335  The Randy Carnahan 16 October 2000 Controlled Flight Into Terrain (CFIT) accident in Missouri was due to half the vacuum-operated instruments going blank causing loss of situational awareness by the pilot flying.  All three occupants of the plane – Missouri Governor Mel Carnahan, his son Randy the pilot flying, and Chris Sifford, campaign advisor and former chief of staff to the governor – perished in the crash.  Passenger Sifford was using his cell phone for most or all the 18-minute flight.  National Transportation Safety Board (NTSB) investigation efforts concentrated on the Cessna vacuum pumps, which were recovered and tested as functional.  I attended the International Society of Air Safety Investigators (ISASI) annual seminar in Washington DC in 2002 or 2003.  One of the social activities was a boat ride on the Potomac River.  During the ride, I had a conversation with the NTSB’s Investigator In Charge (IIC) for the Carnahan accident.  I asked her why she did not investigate the cellular telephone issue.  She replied that she did not know how.

Tg261  This accident, like Christchurch, has been written about extensively by media covering the subject of PED use safety.  It was also discussed in Reference 8.  There were over 40 survivors, many of whom testified about increased passenger use of cellular telephones during the two missed approaches and the fatal CFIT third approach.  I was called by a NTSB staffer who asked about the possibility of pitch control susceptibility to mobile phone emissions.  I don’t think my answer was the one he sought.  My reply was that such susceptibilities were possible and that I would need to review the block and wiring diagrams of the Airbus 310 series aircraft involved for confirmation.  He never responded.

A/A 1340  This is another accident that is a favorite of authors of PED-related articles.  This short landing at O’Hare 14R was briefed during the 22 July 2003 SC-202 WG-3 meeting.  EMI from internal or external sources right over 14R’s middle marker was hypothesized.  Similar glide slope anomalies (EMI?) were experienced by over a dozen other aircraft flight crews.  The NTSB report blamed integrator time constant settings in the autopilot!  This would not explain why other flight crews experienced the ORD 14R glide slope ILS anomalies unless that particular autopilot was interchanged between aircraft of different operators multiple times – ‘Splain that Lucy.  The American Airlines submissions to the NTSB docket for this accident contained many details about EMI possibilities including the finding of passenger PEDs in the wreckage.  For more details see Reference 20.  The safety officer from American Airlines assigned to this investigation was a member of SC-202 and WG-3.  He and I sat with the NTSB IIC for this investigation during one of the meals at the ISASI Washington, DC Annual Seminar referred to above.  The American Airlines safety investigator asked him why he didn’t consider EMI.  He replied that he knew nothing about EMI!  This NTSB IIC didn’t have a clue.  For what it’s worth, my own theory about this accident cause involves external EMI sources and intermodulation.  If my theory is sound, the solution would be to slightly retune the frequency of the ILS glide slope transmitter or replace it.  Subsequent replacement of the glide slope transmitter appears to have been effective.

Air Transit 961  This Airbus 310 in-flight rudder panel loss was poorly investigated with respect to EMI.  The report made no mention of the possibility of passenger PED use and EMI susceptibility of rudder controls.  The report did address HIRF, but did so incorrectly and with no analyses nor tests in validation of the IIC’s conclusion that HIRF was not a contributor.  My rather “unique” theory on this incident may be downloaded from the URL listed in my Reference 1 footnote.  All four elements (source, coupling, victim, & degradation) of a HIRF episode were present.  It isn’t PEDs related but might make for educational reading since there will be much more written about aircraft yaw damping feed-back systems in the following sections.

United 585 and US Air 427  These two fatal approach rudder roll accidents from the early 1990s deserve expanded discussion.  They have never been solved in spite of the public NTSB and FAA statements and reports to the contrary.  My own attempts to educate the air safety investigators about flaws in these investigations have fallen on “deaf ears” or “IIC pomposity”.  My many efforts, starting in 1995, have resulted in frustration and downright paranoia on my part.  I found only two air safety investigators who would listen and recommend recourse, a former NTSB Chairman and a now-retired NTSB IIC.  Two USA Congressmen on the Aviation Subcommittee did, however, aid in access to otherwise unavailable data from the NTSB and FAA.  Their great contributions are beyond the subject of this RFC and are a story for another time and audience.  A subsection of these comments follows and concentrates on these two accidents.  Both involved Boeing 737 Initial (B737-100/-200) or Classic (B737-300/-400/-500) aircraft types.

Other B737 Initial and Classic fatal accidents, in addition to United 585 and US Air 427, are possibly worthy of historical study by the ARC with respect to PEDs.  They include:  Condor Flugdienst 3782, Indian Airlines 113, US Air 5050, Indian Airlines 257, China Southern 3943, Asiana Airlines 733, Turkish Airlines TK278, Aviateca 901, Faucett 251, Silkair 185, Peruvian Air Force FAP-351, Air Philippines GAP541, Indian Air IC 7412, Egypt Air 843, Air Algerie 6289, Sudan Airways 39, Flash Airlines 604, D.B.A. Kan Airlines EX-037, and the recent Bhoja Airlines B4 213.

UNITED 585 and US AIRLINES 427

Disclaimer  The reader will soon realize that this subsection brings up the issue of cellular telephone use on board aircraft, which is specifically excluded from the subject RFC.  This commenter has read DOT/FAA/AR-12/30[23] and is aware that the FAA is following the world-wide use of cellular telephones on aircraft of other nations.  This effort was part of the FAA Modernization and Reform Act of 2012 that directed the FAA to conduct a study on the impact of the use of cell phones for voice communications in an aircraft during a flight in scheduled passenger air transportation.  FAA, the subject appears to be on the table!

Background  These two accidents happened two decades ago and may not be well remembered by the readers.

The United 585 accident occurred March 3, 1991 on approach to runway 35L at Colorado Springs, CO.  The aircraft involved was N999UA, which had suffered two recoverable yaw upsets in the week prior to the fatal rudder roll.  This airplane had a problem that wasn’t fixed.  The flight data recorder was ancient and recorded only five parameters.  Six United Airlines employees and 19 passengers perished.  The body of a 20-year-old young man, who had died in an auto accident in Nebraska, was also lost.  Included as passengers was the brother of a Christian counselor who was instrumental in forming The Grief Share Ministry and several officials of the USA Olympic Training Center located at Colorado Springs.

United 585 was listed as unsolved by the NTSB for the next ten years.  Many consider it remaining unsolved.  The NTSB docket for this investigation has not been digitized.  It is available for reading (ask for Microfiche DCA-91-M-A023) in the NTSB’s reading room at their L’Enfant Plaza headquarters in Washington, DC.

The US Airlines (US Air) 427 accident occurred September 8, 1994 at Aliquippa, PA on approach to runway 28R at Pittsburgh.  The rudder roll was not recoverable, and all 132 on board perished.

This accident also remains unsolved.

So Many Words, So Few Answers  Three NTSB reports[24]^{, [25], [26]}, a Pulitzer Prize-winning newspaper series[27], a Reader’s Digest feature article[28], and three books[29]^{, [30], [31]} have been written about these accidents.  One of the coauthors of Reference 30 is one of five presidential appointed members of the NTSB.  The author of references 28 and 31 has also been awarded a Pulitzer Prize.  It was for his work establishing and maintaining the political fact-checking web site PolitiFact.com.

None of these documents identified the source(s) of the uncommanded rudder movement.  Many suggested a sticking and over travelling dual-concentric hydraulic valve in the rudder Power Control Unit (PCU).  That theory did not hold up.  Page 88 of Reference 28 shows a photo of a senior NTSB investigator, with whom I worked multiple times, looking “quizzically” at the suspect hydraulic valve.  He worked on both these investigations and never agreed with the sticking-valve theory.  He is now a consultant.

Three letters to the editor of the respected AVIATION WEEK AND SPACE TECHNOLOGY magazine, on the subject of these accidents, were also published.  They were Kane’s on pp14-15 10/23/00 issue, Mahon’s on p8 4/26/99 issue, and the best by Bruce Haxthausen p6 9/25/95 issue.  Haxthausen suggested passenger cell phone use as a possible cause.  Bruce, from New York City, and I have exchanged a number of e mails!

There have also probably been several million words on the subject generated by litigation attorneys.  Those folks bill by the hour.

I once enjoyed a short DC Metro ride after a Mid Atlantic Region ISASI meeting.  I shared a seat with former NTSB Chairman Jim Hall.  Jim asked me why I didn’t write a book about these two accidents.  I replied that there had been too many already written.  Also, such a book would have a limited market.  Chairman Hall, if you are reading this, here is my book!  Thanks for being one of the few believers.

Dropping the Other Shoe – Some Facts  Many checkable facts will be presented in the remainder of this section so that the reader may arrive at his/her own conclusions.

Fact One – Initial and Classic B737 aircraft suffered many yaw upsets during the decades of the 1980’s and 1990’s.  A limited number of them were listed in Appendix E of Reference 25.

            Fact Two – These yaw upsets subsided in late 2000.

            Fact Three – The Next Generation (NG) Boeing 737’s (737-600, -700, -800, & -900) did not suffer yaw upsets with the exception of one attributed to a strong cross wind and one on a Southwest -700 during a takeoff 8/98.

            Fact Four – These two accidents involved Initial or Classic B737s.

            Fact Five – There is a huge clue presented in Facts One through Four above that is both basic and that was overlooked in 21 years of investigation.

            Fact Six – There was a significant configuration difference between the Initial/Classic and NG B737’s.

            Fact Seven – The Initial/Classic B737s were originally equipped with an old analog yaw damper coupler manufactured by Sperry/Honeywell.

            Fact Eight – The NG 737s were equipped with a digital yaw damper coupler derived from the B757 version.

Fact Nine – All B737’s delivered prior to 1997 were equipped with the suspect PCU dual-concentric hydraulic valve.  An Airworthiness Directive (AD 97-14-03) dated 8/1/97 required that all the valves be replaced within two years with a redesigned valve that could not misport even if it stuck and over travelled.  See page 331 of Reference 25.

            Fact Ten – All the Initial/Classic B737 analog yaw damper couplers were replaced with the digital design by late 2000.  AD 97-14-04 dated 8/1/97 required the replacement yaw damper coupler within three years.  See page 331 of Reference 25.  The manufacturer evidently couldn’t build them fast enough to meet the 8/1/00 date, so they did not all get replaced until late 2000.

AD/B737/123 was issued to allow extension of the date until March 2002.

 

            Fact 11 – The NTSB received incorrect information with respect to the operation of the yaw damper coupler.  They were told that control-law parameters were programmed into the coupler so that the rudder control authority would never exceed three degrees and that yaw damper corrections could be easily countered by flight crew use of the rudder pedals.  This information is probably right if the coupler is operating correctly.  However, failure modes of the yaw damper were not investigated other than the review of multiple Air France upset events traced to one or more failed operational amplifiers in the coupler.

Fact 12 – An EMI susceptibility is not normal.  Assuming that systems operate normally when suffering EMI susceptibility is naive.

Even the FAA fell into this trap.  They invited public comment on the proposed AD for the total redesign of the B737 rudder control system.  Howard Swancy was the FAA action officer.  Howard was part of the 1996 USAF IFO 21/CT-43A Accident/Safety Investigation, so I knew him and thought my comments would be treated seriously.  They were not.  See for yourself.

 

Note that next-to-last sentence with discussion of electrical interference and a normally functioning system.  There is nothing normal about EMI susceptibilities.  I got even less respect than Rodney Dangerfield!

            Fact 13 – It is possible to work backward from the effective fixes to solve these accidents.  No one has yet bothered to do so.  Well, actually I have.  If NTSB/FAA did, they have not yet made it public.  Please do so.

Fact 14 – Several military aircraft flight and engine control systems were discovered to be susceptible to EMI and had to be fixed.  Some details were presented in various references listed in Appendix A and also in Reference 20.  The F-4 Phantom II and S-3A Viking rudder controls were EMI susceptible as was the UH-60 Blackhawk horizontal stabilizer controls.  The F-4 Aileron-Rudder Interconnect, S-3A Yaw Damper Coupler, and UH-60 Stability Augmentation System have circuitry and designs similar to that of the Initial/Classic B737 analog yaw damper coupler.  They are also of the same 1960’s eras.

There is an interesting paragraph in the lessons-learned Appendix A of MIL-STD-464C (Reference A-1), as copied below:

 

This indicates that wire shielding can be degraded with inadequate bonding of the interfaced avionics box.  The Aging Aircraft Wiring study that followed the TWA800 investigation found that wire shielding effectiveness degraded over time.  SC-202 WG-3 had the aging wiring study leader, Kent Hollinger, as a member.  His wife and I attended the same engineering university in the Missouri Ozarks.

Feed-back loops in military jet engine controls almost always were found to be HIRF/EMI susceptible requiring additional wire shielding and box filtering.

Repeated attempts to educate the NTSB and FAA aircraft safety office staffs about military aircraft EMI susceptibility were ineffective.  Electronic mails were ignored, and offers to brief the staff were rejected.  One NTSB staffer replied to my request to brief this expertise and military experiences by stating that I would have to pay the hourly salaries of any NTSB employee who attended.  They are civil servants.  I already pay their salaries (every April 15^th).

However, I was allowed to brief their staff at a lunch-time brown-bag brief on February 1, 1996 prior to my learning many of the details about these two accidents.  I included the F-4 and UH-60 stories during that brief.  It was well attended including two of the NTSB members.  Attendance by more than two (of the five) is prohibited by the Sunshine Law.  The brief given was an early version of Reference 20.

Fact 15  The B737 yaw upsets started when cellular telephones became popular.

            Fact 16  Early cellular telephones in the USA had higher duty cycles and powers than those in use today.

            Fact 17  Multiple tests have proven that the B737 analog yaw damper coupler was EMI susceptible.  I know of two, but there have probably been more.

One of the Air Safety Newsgroups had multiple and excellent late 1990’s postings about the Boeing 737 yaw upsets and accidents.   I saved approximately 100 of the best to computer files.  A select few are included with these comments as Appendix C.  Note especially those postings by “Captain Bligh” and John Hilt.  I suspect they are the same person.  Whoever it is/was seemed to have first-person knowledge of a B737 ground test in Europe where the aircraft was placed on jacks, a person physically moved the yaw damper coupler in the avionics bay to simulate yaw, and another person walked the cabin using a Global System for Mobile (GSM) communications Time Division Multiple Access (TDMA) cellular telephone.  GSM is the standard cell phone in much of the world outside the USA, where a lower-powered format (Code Division Multiple Access) is universal.  The phone batteries in the USA need to be charged less often.  Hilt reports yaw damper EMI susceptibilities from the high-power GSM phone(s).

The other test was performed by the FAA’s Engineering Test and Evaluation Board (ETEB) during 1999-2000.[32]  This board was formed due to a recommendation from the NTSB as contained in their USAir 427 report (Reference 25).  The ETEB experienced an 11-degree yaw damper rudder hard over due to EMI coupled to the rudder position feed-back loop during a “closed-loop” test.  This disproved the much publicized 3-degree yaw damper limit story.

            Fact 18  The FAA ETEB received incorrect information with respect to the operation of the yaw damper coupler.  There are multiple references, contained in Reference 32, describing yaw damper open-loop operation during tests.  This is gibberish.  The yaw damper cannot operate in an open-loop mode.  It operates closed loop allowing the feed-back loop to discern rudder position and to send a reverse signal indicating additional correction needed to position the rudder to the proper position.  To operate the yaw damper open loop requires that the feed-back loop be disconnected.  They, in effect, took hardware out of the loop.  Conversely, the ETEB took great effort to put pilots in the loop for any tests requiring flight-deck crew inputs.

Did someone know the loop was EMI susceptible?  A better question would be:  Why did the ETEB agree to take hardware out of the loop?  “You’ve got some splainin’ to do, Lucy” (Desi Arnez, I LOVE LUCY, almost every episode).

            Fact 19  The FAA ETEB did not welcome my input.  I called the FAA ETEB Team Lead in the summer of 1999 and shared the EMI theory.  I also volunteered to serve on the ETEB.  Since I was a contractor, I mentioned that I would need to be paid for my services.  He passed me off to his Control Systems Analysis team leader, and I again presented the EMI theory.  Nothing ever resulted from my offer.  In fact, EMI was not even part of the ETEB’s fault-tree analysis.  Their finding of EMI during testing was an accident.

I was not invited to join the ETEB.  I was actually disqualified since I had worked on a prior B737 accident investigation, and they wanted “novices”.  I wasn’t even invited to brief the ETEB.

The lone DoD representative on the ETEB was a US Navy civilian engineer from the Naval Air Test Center in southern Maryland.  He is a hydraulics expert, as were many of the ETEB members.  This engineer was a fellow deacon in our Annapolis church.  He said that my EMI theory was treated with derision and that objectivity was discouraged.  He was not even presented with a copy of Reference 32.

Fact 20  The Initial/Classic B737 yaw upsets continued after replacement of the suspect dual-concentric hydraulic valve.  There were at least 16 reported Initial/Classic B737 events.  Details concerning one incident, MetroJet 2710, was documented in Reference 25 (pp 160-161).  It had the NTSB “scratching their heads” at the March 1999 Sunshine Review of Reference 25.  Others are summarized in Appendix C.  One during a landing at Houston/Hobby displayed expert airmanship.  The ASRS report for this event is included as Appendix D and is recommended reading.  When originally posted, the airport was identified as IAH.  Someone changed it to ZZZ later.

            Fact 21  The Colorado Springs, CO and Aliquippa, PA external electromagnetic environments were vastly different.  Aliquippa is benign with respect to ground transmitters.  Colorado Springs was and is very active.

There were approximately 2,000 transmitter antennas in the Colorado Springs local environment at the time of the United 585 accident.  The US North American Aerospace Defense Command’s Cheyenne Mountain (http://en.wikipedia.org/wiki/Cheyenne_Mountain) is nearby.  Many Boeing 737 aircraft, including the USAF fleets of T-43As, have operated from this airport without suffering HIRF upsets.  My conclusion (do not allow me to taint yours) is that these two accidents, if caused by EMI, were not due to external environments, but rather from internal-to-the-cabin sources.  It’s a stretch – I realize it.

            Fact 22  Pilot reports from many of the B737 yaw upset events reported rudder pedal movement.  The yaw damper adder is connected to the torque tube in the vertical stabilizer. Once a commanded correction reaches the mechanical limit, forces are exerted against the torque tube (F = MA).  The rudder pedal cables also attach to that torque tube.

One excellent example, Eastwinds 517, is described on pages 51-54 of Reference 25.

Rudder pedal movement accompanied the EMI yaw damper hard over event reported by the ETEB in Reference 32.

Fact 23  Switching the yaw damper to “off” using the cockpit switch is not instantaneous.  One system block diagram I used in Reference 20 shows that the switch turns off the two-minute integrator, not the system.  Crews of U999UA the week prior to the United 585 accident (twice) had to pull the yaw damper circuit breaker to regain control.  Interviews with these flight crews were not recorded in the NTSB’s United 585 docket.  They knew something valuable.

            Fact 24  Aircraft yaw dampers are complex.  There is a lot going on in that small box in the avionics bay and in the PCU it controls.  While studying these two accidents, I tried to educate myself on yaw damper operation.  Early work came out of NASA/Langley in the early 1950’s after swept-wing aircraft became dominant.  They found that yaw damper second-order differential equation solutions could work with damping ratios from about 0.5 to 5.0, a wide range.

I’ve ridden in the rear of Boeing, Douglas, Lockheed, Convair, and Airbus commercial airplanes.  The Airbus products move around a lot back there suggesting under damping.  Their dampers would probably recover more quickly to an engine failure than an over-damped aircraft.  The others were very stable, suggesting critical or over damping.  The critical damping ratio is defined as unity.

I even called the chief scientist of the USAF to ask about the best text book on the subject.  He replied that it was still the text I used 50 years ago at Rolla my senior year in college, D’Azzo & Houpis.[33]  The fact that these two authors were from the USAF might have influenced his suggestion.

During my correspondence with reporter Gary Stoller of USA Today last December, I tried to interest him in researching these two accidents.  My attempts to explain yaw damper system operations to him, in laymen’s terms, is worthy of repeating in these comments.  They are copied below:

 

 

            Fact 25  Someone on the NTSB US Air 427 investigation team was listening.  There are two clues contained in Reference 25.

The first is a sentence and footnote 235 found on page 152.  It discusses consideration of EMI and HIRF with respect to the yaw damper coupler.  No details were presented.  Footnote 235 is copied below for the readers’ convenience.

The second was two interesting and related recommendations that made it into Reference 25.

And

It appears that someone else was concerned about my “least-favorite” aircraft feed-back loop.

Fact 26  These were/are the longest investigations in NTSB history.  Chapter 1 of Reference 30 is properly titled.  After 21 years, these two accidents are still not resolved.  The NTSB published References 25 and 26 in order to close their books and get on with other things.  They passed the problem to the FAA.

The NTSB chairman even mentioned the lengthy investigations in a recent speech she gave to ISASI on the subject of data mining.[34]  Considering that the NTSB ignored the DoD aircraft data, these investigations would be better fitting for a speech about data burial.

The Sunshine Review of the US Air 427 report (Reference 25) was held over two days in March 1999.  The NTSB had not yet obtained the large theater seating room in the basement of the 490 L’Enfant Plaza Headquarters building, so the review was held in the ballroom of a hotel in northern Virginia near the I-95/495 “Mixing Bowl”.  I attended both days in order to discern the completeness of the investigation.

The room was full of interested folks and media.  People were walking the halls muttering “why don’t they just tell us what caused the rudder to move?”

It quickly became obvious that they didn’t know.

I wanted to tell them, but public input is not allowed and will get you quickly and forcefully escorted to the door.  As an alternative, I tried working the halls, side rooms, and outdoor “smoking” areas.  I had mixed success.

Only four of the five NTSB members participated.  The fifth had recused himself since he was a former US Airlines employee.  One of the other four is an engineer.  I had been introduced to him when I briefed my TWA800 investigation progress.  I stopped him in the hall prior to the meeting, but I didn’t have a chance to share my theory, which isn’t easily or quickly told.  He was far too busy to listen.

Next, I caught the safety representative from the pilots’ union, the Air Line Pilots Association, International.  He listened to the beginning of the story until we were interrupted by someone from the media.  He broke away and spoke to the media, as that was his reason for attending.  It was only several years later, at an ISASI meeting, that I was able to finish the story.  He had played an active role in the USAir 427 investigation since he was a USAir check ride Captain and was called upon to be the test pilot for one or more flight tests.  He is now an air safety consultant and hosts the USA Today “Ask the Captain” blog.  He has gotten a lot of questions submitted to him with respect to PED safety.  His answers have been non committal but always stress safety.  He’s one of the good guys.

I sat on the back row next to a Boeing vice president.  He asked why I was there.  I mentioned being part of the IFO 21/CT-43A investigation and was attending out of curiosity.  He then told me I had chosen a great Sunshine Review to attend.  He also admitted “we’ve got a bad yaw damper.”  We later exchanged electronic mails (one each!).

One of the most interesting encounters at this meeting occurred during the afternoon break the first day.  I went outside to enjoy the unseasonable warm March day.  I was approached by a fellow attendee.  After exchanging pleasantries, he introduced himself as a Vice President of the insurance carrier AIG out of their Atlanta office.  He mentioned that they had made settlements with most of the families.  He then asked about my story.  I again mentioned IFO 21.  He sought my opinion about USAir 427.  I then pointed to about six others outside and said, in turn, there’s one, there’s another, etc.  They were all making cellular telephone calls since their phones had to be disabled during the Sunshine Review.  “You mean cell phones?”  “Yes.”  We exchanged business cards.  He didn’t ask a single clarification question.

I never heard from him again.  However, an attorney from Los Angeles called 2-1/2 years later.  I vividly remember the date of the call.  It was Tuesday September 4, 2001.  Exactly one week later I had to miss the second-Tuesday-of-each-month 11 AM Search and Rescue Technology meeting in the Pentagon.  That was a crazy day in DC (as it was in New York and PA).

After the telephoning lawyer made his introductions, he said that he had been advised to get my opinion on the B737 rudder issue.  I said “It certainly was not a sticking hydraulic valve.”  He replied with the exact same statement.  After I gave him details, there was silence on the phone.  He stated he would have to check with the PCU manufacturer engineers and get back to me.  I’m still waiting for him to return the call 11 years later.  I can only guess his role – some lawyer has to be paid to be the loser in litigation.

I did see him shown in a National Geographic cable TV feature about the SilkAir 185 investigation and subsequent litigation.  He was shown descending the Los Angeles County Court House steps at the 5:12 point in this youtube, segment 5 of 5, taken from the TV show:  http://www.youtube.com/watch?v=zvDVHfAOyfU&feature=BFa&list=PL4BFCB27012AA884C.  The reader may wish to watch all five segments about this interesting accident.  Was it fratricide or mechanical?

The National Geographic TV show narrator was Gregory Feith who is a retired NTSB Senior Investigator.  He was one of the two co sponsors for my full ISASI membership.

I returned for the second day of the Sunshine Review.  It was tedious and detail oriented, so I hung out in the side room used by the NTSB to showcase their other investigations.

I spent some minutes with Greg Feith explaining the EMI theory.  He listened intently and gave positive body language.  However, he failed to recommend any follow up actions.

The NTSB’s TWA800 IIC was standing nearby at a table displaying the TWA800 break-up sequence graphic.  He was also the United 585 IIC and had not yet issued his revised report (Reference 26).

No one else was around, so I told him an expanded version of the EMI theory.  He also listened intently and never interrupted.

Upon my finish, he recommended that I write a letter to the five NTSB members, which I did 20 months later.

His guidance was the only other (besides the Metro ride with Jim Hall) encouraging interaction I had with the NTSB during this frustrating process.

He is now retired.  Live long and prosper, Al Dickinson.  Thank you so much.

My letter to the NTSB was delayed 20 months to allow the ETEB to finish their work (Reference 32) and for all the old analog yaw damper couplers to be replaced with the digital version.

I was actually hoping my theory was incorrect in spite of all the data indicating otherwise.

My November 2000 letter is included in these comments as Appendix E.  It was addressed to the engineer board member with copies to the other four.

NTSB has a practice of answering letters from the public.  They did not answer this one, however I did get a call from a staff member several months later asking what I wanted.  My reply was simple:  “Fix the d—n airplanes.”  He replied:  “I can’t.”

In retrospect, it turns out the planes had been fixed by late 2000.  The various ADs worked, especially the two that replaced the old yaw damper couplers.  The effectiveness of the other ADs awaits being revealed.

Fact 27  There are many lessons to be learned from these two investigations.  I posted 20 to the ISASI Group on LinkedIn.com several months ago.  They are copied here as Appendix F for the education of the reader and ARC if formed.  Please align policy such that these mistakes never happen again.

            Fact 28  This one is the most important – the B737 yaw problems got fixed.

 

CONCLUDING COMMENT

I wish to thank John Hickey, Susan Cabler, Timothy Shaver and the other FAA staff for allowing the public to submit comments on this important safety subject and for posting them to the public-access www.regulations.gov web site.

 

Respectfully submitted,

 

Douglas J. Hughes

Ann Arbor, MI

REFERENCES

1. Hughes, D.J.; Wireless Aboard, Why All The Fuss?, verbal presentation given most recently to the Institute of Electrical and Electronic Engineers (IEEE) SE Michigan EMC and Aerospace Electronics Society Chapters, Dearborn, MI, September 14, 2011.  Slides available at:  http://www.emcsociety.org/2011%20Events/September_14_2011.htm (play in slide-show mode)
2. RTCA Inc. Interference to Aircraft Electronic Equipment from Devices Carried Aboard, DO-119. Washington, D.C.: RTCA, Inc., 12 April 1963.
3. RTCA Inc. Potential Interference to Aircraft Electronic Equipment from Devices Carried Onboard, DO-199. Washington, D.C.: RTCA Inc., September 1988.
4. RTCA Inc. Portable Electronic Devices Carried on Board Aircraft, DO-233. Washington, D.C.: RTCA, Inc., August 1996.
5. RTCA. Inc. Guidance on Allowing Transmitting Portable Electronic Devices (T-PEDs) on Aircraft, DO-294. Washington, D.C.: RTCA, Inc., 19 October 2004.
6. NASA. Portable Electronic Devices and Their Interference with Aircraft Systems. NASA/CR-2001-210866, Hampton, Virginia: NASA Langley Research Center, June 2001.
7. NASA. Portable Wireless LAN Device and Two-Way Radio Threat Assessment for Aircraft Navigation Radios. NASA/TP-2003-212438, Hampton, Virginia: NASA Langley Research Center, July 2003.
8. Aghdassi, BN; An Assessment of The Use of Portable Electronic Devices (PEDs), On Board Aircraft, And Their Implications On Flight Safety, Chapter 4 – The Airlines’ Perspective, MSc Thesis, Cranfield University, College of Aeronautics, 1999.
9. Strauss, Graham William; Portable Electronic Devices Onboard Commercial Aircraft: Assessing the Risks, Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy, Carnegie Mellon University, CARNEGIE INSTITUTE OF TECHNOLOGY, Pittsburgh, PA http://www.next-up.org/pdf/Carnerie_Mellon_University_thesis_William_Strauss_Portable_Electronic_Device_Onboard_Aircraft_Assessing_Risks.pdf

1. Sorkin, Aaron; The West Wing, Season One, Episode One, Warner Brothers Television, Aired September 22, 1999, NBC  http://www.youtube.com/watch?v=U6JvTshE6aY
2. Johnson, Joel; Can my iPod Make This Airplane Explode?, GIZMODO, December 7, 2009, http://gizmodo.com/5420641/can-my-ipod-make-this-airplane-explode
3. Negroni, Christine;  Interfering With Flight?, New York Times, NY, January 17, 2011 http://www.nytimes.com/2011/01/18/business/18devices.html?_r=2&ref=business
4. Negroni, Christine; Cellphone dangers on planes.  My comments on MSNBC, Flying Lessons Blog  http://christinenegroni.blogspot.com/
5. Ross, Brian & ABC News Team; Cellphone Use on Planes Safety Threat?, Newscast.  June 9, 2011 http://abcnews.go.com/WNT/video/cellphone-use-on-planes-safety-threat-13806022
6. Costello, Tom & NBC News Team; Can mobile devices really interfere with a plane?, NBC Evening Newscast, October 10, 2011  http://overheadbin.nbcnews.com/_news/2011/10/10/8259156-can-mobile-devices-really-interfere-with-a-plane?lite
7. Stoller, Gary; Many fliers refuse to turn off electronic gadgets, USA Today Feature, December 21, 2011 http://travel.usatoday.com/flights/story/2011-12-21/Many-fliers-refuse-to-turn-off-electronic-gadgets/52146544/1?loc=interstitialskip
8. Editor; Fliers, think before turning on electronics, USA Today Editorial, December 21, 2011  http://www.usatoday.com/news/opinion/editorials/story/2011-12-21/in-flight-electronics-planes/52147604/1
9. Hughes, D.J., Linehan, J.E., and Perez, R.; AN/PRQ-7 COCKPIT SAFETY STUDY, JSC-CR-01-066, DoD Joint Spectrum Center, Annapolis, MD, March 2002.
10. Hughes, D.J.; AN/PRQ-7 SPECTRUM CERTIFICATION SUPPORT, JSC-PR-02-013, DoD Joint Spectrum Center, Annapolis, MD, July 2002.
11. Walen, D.B., Chitwood, R.A, B. DeCleene, B., and Shaver, T.; Study on the Use of Cell Phones on Passenger Aircraft, DOT/FAA/AR-12/30, Federal Aviation Agency, Washington, DC, July 2012
12. United Airlines Flight 585, Boeing 737-291, N999UA, Uncontrolled Collision With Terrain For Undetermined Reasons, 4 Miles South Of Colorado Springs Municipal Airport, Colorado Springs, Colorado; Aircraft Accident Report; National Transportation Safety Board; Washington, D.C.; NTSB/AAR-92/06; Adopted December 8, 1992.
13. Acohido, Byron; Safety at issue: the 737; The Seattle Times; August 27, 1996.  Accessible at: http://www.pulitzer.org/archives/5924
14. Adair, Bill; Mystery of Flight 427; Reader’s Digest; October 1999; pp84-90.
15. Byrne, Gerry; Flight 427 Anatomy of an Air Disaster; Copernicus Books, 37 East 7^th Street, New York, NY 10003; ©2000.
16. 30.  Walters, J.M. and Sumwalt III, R.L.; Aircraft Accident Analysis:  Final Reports; Chapter1.  The longest investigation in U.S. History:  USAir flight 427; McGraw-Hill; Two Penn Plaza; New York, NY 10121-2298; ©2000.
17. Adair, Bill; The Mystery of Flight 427: Inside a Crash Investigation; Smithsonian Books; Washington, DC: ©1999.
18. Hersman, D.A.P.; Evolution of Aviation Safety: From Reactive to Predictive; NTSB; International Society of Air Safety Investigators Annual Seminar; Baltimore, MD; August 28, 2012.

18. Greenemeier, Larry; 10 Facts about Portable Electronics and Airplanes, Scientific American, December 22, 2011 http://blogs.scientificamerican.com/observations/2011/12/22/10-facts-about-portable-electronics-and-airplanes/
19. Blackstone, John & CBS News Team:  Is using devices on planes really dangerous?, Morning newscast, January 27, 2012  http://www.cbsnews.com/8301-505263_162-57367281/is-using-devices-on-planes-really-dangerous/?tag=cbsnewsSectionContent.0
20. Hughes, D.J.; Aircraft Electromagnetic Environmental Effects and Safety, verbal presentation given multiple times but most recently to the Southeast Michigan IEEE EMC and Aerospace Electronics Chapters, Dearborn, MI, March 15, 2012.  Slides available from:  http://www.emcsociety.org/2012%20Events/AIRCRAFT%20ELECTROMAGNETIC%20ENVIRONMENTAL%20EFFECTS%20AND%20SAFETY%20Part%202.htm (play in slide-show mode)

25. Uncontrolled Descent And Collision With Terrain, USAir Flight 427, Boeing 737-300, N513AU, Near Aliquippa, Pennsylvania, SEPTEMBER 8, 1994; National Transportation Safety Board; Washington, D.C.;.; NTSB/AAR-99/01; Adopted March 24, 1999 and correct November 4, 1999 and February 16, 2000.
26. Uncontrolled Descent and Collision With Terrain, United Airlines Flight 585, Boeing 737-200, N999UA, 4 Miles South of Colorado Springs Municipal Airport, Colorado Springs, Colorado, March 3, 1991; Aircraft Accident Report; National Transportation Safety Board; Washington, D.C.; NTSB/AAR-01/01; Adopted March 27, 2001.

32. McGraw, John; et.al.;737 Flight Controls Engineering Test and Evaluation Board; Final Report; Federal Aviation Administration; July 20, 2000.
33. D’Azzo, J.J. and Houpis, C.H.; Feedback Control System Analysis and Synthesis; McGraw-Hill Book Company, Inc.; New York; ©1960.

APPENDIX A

AIRCRAFT HIGH INTENSITY RADIATED FIELDS (HIRF) SUSCEPTIBILITY

by

DOUGLAS J. HUGHES, ISASI MO4415

MAJOR REFERENCES

A-1.          “ELECTROMAGNETIC ENVIRONMENTAL EFFECTS REQUIREMENTS FOR SYSTEMS,” Department of Defense, MIL-STD-464C, 1 December 2010.

 

A-2.          “MILITARY OPERATIONAL ELECTROMAGNETIC ENVIRONMENTAL PROFILES,” Department of Defense, MIL-HDBK-235-1C, 1 October 2010.

 

A-3.          “ENVIRONMENTAL CONDITIONS AND TEST PROCEDURES FOR AIRBORNE EQUIPMENT,” DO-160G, RTCA Incorporated, Washington, D.C., 8 December 2010 (EUROCAE/ED-14G is identically worded).

 

SECONDARY REFERENCES

 

A-4.          http://en.wikipedia.org/wiki/Fly-by-wire

A-5.          Belcastro, C.M; & Jacobson, S.R.; “Future Integrated Systems Concept for Preventing Aircraft Loss-of-Control Accidents,” NASA LaRC 20100031283, 8 August 2010.

A-6.          “Application of High-intensity Radiated Fields (HIRF) Protection Final Rule under §21.101,” 14 Code of Federal Regulations (CFR) §-§2L16, 21.1O1~23.1308, 25.1317, 27.1317, and 29.1317. Federal Aviation Administration (FAA), AIR-100, 26 February 2008.

A-7.          Koppen, S.V.; Ely, J.J.; Smith, L.J.; Jones, R.A.; Fleck, V.J.; Salud, M.T.; & Mielnik, J.J.; “Airborne RF Measurement System (ARMS) and Analysis of Representative Flight RF Environment,” NASA LaRC 20070023640, July 2007.

A-8.          “Loss Of Rudder In Flight, Air Transit AIRBUS A310-308 C-GPAT, Miami, Florida, 90 nm S, 06 March 2005,” Aviation Investigation Report A05F0047, Transportation Safety Board of Canada, 2007.

A-9.          Nguyen, T.X.; Ely, J.J.; Dudley, K.L.; Scearce, S.A.; Hatfield, M.O.; & Richardson, R.E.; “Passenger Transmitters As Possible Cause Of Aircraft Fuel Ignition-In Support Of An Aircraft Accident Investigation” Presented At The 2006 IEEE Symposium On EMC, Portland, Oregon, 15 August 2006.

 

A-10.      Belcastro, C.M.; Chowdhury, F.; Cheng, Q.; Michels, J.H.; & Varshney, P.K.;  “Distributed Detection with Data Fusion for Aircraft Flight Control Computer Malfunction Monitoring,” NASA LaRC, VA, AIAA 2005-6358, AIAA Guidance, Navigation, and Control Conference and Exhibit, San Francisco, CA, 15-18 August 2005.

A-11.      “Electromagnetic Compatibility Measurements Procedure for Vehicle Components-Part 28: Immunity to Radiated Electromagnetic Fields-Reverberation Method (Mode Tuning),” Standard SAE J1113/28, Draft June 2004.

A-12.      Belcastro, C.M.; “Closed-Loop Hirf Experiments Performed On A Fault Tolerant Flight Control Computer,” NASA LaRC, VA, 2004107280, 2004.

A-13.      Balanis, C.A.; Birtcher, C.R.; Georgakopoulos, S.V.; & Panaretos, A.H.; “Penetration of High Intensity Radiated Fields (HIRF) Into General Aviation Aircraft,” NASA LaRC, VA, 20040084537, 31 May 2004.

A-14.      Hatfield, M.O.; Pluim, W.P.; & Price, W.O.; “Investigation Into In-Situ Shielding Effectiveness Testing Of Transport Aircraft” Presented At The 2003 IEEE Symposium On EMC, Boston, Massacushetts, 20 August 2003.

A-15.      Goldsmith, K.; & Freyer G.; “Using a ‘Mini’ Reverb Chamber to Evaluate the Wing of an Aircraft,” The 2003 Reverberation Chamber, Anechoic Chamber and OATS Users Meeting, Austin, TX, April 2003.

A-16.      Rimson, I.J.; “The Impact of Fly-By-Wire (And Other Computer-Controlled Systems) on Aircraft Accident Investigations,” System Safety Associates Ltd., Springfield, VA, Private Correspondence, December 2002.

A-17.      Maas, J.; & Moehr, D.E.C.; “How Does IEC SC77B Handle Different Radiated Immunity Test Methods and What is the Present Status?,” IEEE Int. Symposium on EMC, Minneapolis, August 2002.

A-18.      Hughes, D.J.; “EMC COSITE Analysis of The MARK XIIA MODE 5 On F/A-18C/D/E/F Aircraft,” JSC‑CR‑01-027, DoD Joint Spectrum Center, Annapolis, MD, April 2002.

A-19.      Hughes, D.J.; “Aircraft E3 Upsets,” 2001 DoD E3 Program Review, Las Vegas, NV, 5 April, 2001.

A-20.      Moeller, K.J.; Dudley, K.L.; Quach, C.C.; & Koppen, S.V.; “In-Flight Characterization of the Electromagnetic Environment Inside an Airliner,” NASA LaRC 20010045828, March 2001.

A-21.      Nguyen, T.X.; “RF Loading Effects of Aircraft Seats in an Electromagnetic Reverberating Environment,” NASA LaRC 20010020387, December 2000.

A-22.      Libertino, A. Jr; Finch, L.; & Hughes, D.J.; “EMC COSITE Analysis For Global Air Traffic Management Systems (GATM) On The KC-10A Aircraft,” JSC-CR-00-033, DoD Joint Spectrum Center, Annapolis, MD, September 2000.

A-23.       “In-flight Breakup Over The Atlantic Ocean, Trans World Airlines Flight 800, Boeing 747-131, N93119, Near East Moriches, New York, July 17, 1996,” Aircraft Accident Report, NTSB/AAR-00/03, Washington, D.C., 23 August 2000.

A-24.      Min. L.; Nuebel, J.; Drewniak. J.L.; Hubing T.H.; DuBroff R.E.; & Van Doren, T.P.; “EMI Reduction from Airflow Aperture Arrays Using Dual-Perforated Screens and Loss,” IEEE Transactions on Electromagnetic Compatibility, Vol. 42, pp 135-141, May 2000.

A-25.      St. John, R.H.; & Holland R.; “Field-Component Statistics of Externally Illuminated Overmoded Cavities,” IEEE Transactions on Electromagnetic Compatibility, Vol. 42, pp 125-134, May 2000.

A-26.      Ely, J.J.; Nguyen, T.X.; Dudley, K.L.; Scearce, S.A.; Beck, F.B.; Deshpande, M.D.; & Cockrell, C. R.; “Investigation of Electromagnetic Field Threat to Fuel Tank Wiring of a Transport Aircraft,” NASA LaRC 20000060830, March 2000.

A-27.      Chandrasekhar, N.S.; Parthasarathy, T.; & Rao, P.N.A.P.; “EMI Problems During System Integration of a Modern Fighter Aircraft – A Case Study,” IEEE EMC Symposium, 1999.

A-28.      Erickson, G. &  Rimbey P.R; “Mode-Stirred in situ Airplane and Laboratory Tests,” 1999 Mode-Stirred Chamber, Anechoic Chamber and OATS Users Meeting, Northbrook, IL, June 1999.

A-29.      Hagen, M.; Johnson, D.M.; & Slocum, M.B.; “Performance of High-Power Radiated Susceptibility Test of FADEC Systems in Reverberation Chambers,” 1999 Mode-Stirred Chamber, Anechoic Chamber and OATS Users Meeting, Northbrook, IL, June 1999.

A-30.      Goldsmith, K. & Carter, N.;  “The Use of Reverberation Chambers for Aircraft EM Coupling Measurements,” 1999 Mode-Stirred Chamber, Anechoic Chamber and OATS Users Meeting, Northbrook, IL, June 1999.

A-31.      Hughes, D.J. & Macrae, M.; “TWA Flight 800 Electromagnetic Environment,” JSC-CR-99-006, DoD Joint Spectrum Center, Annapolis, MD, January 1999.  (Plus JSC-CR-99-006A in September 1999 and last paragraph on page 160 of NTSB/AAR-00/03 TWA800 report).

A-32.      Johnson, D.M.; Hatfield, M.O.; Slocum, M.B.; & Freyer, G.J.; “Comparison of RF Coupling to Passenger Aircraft Avionics Measured on a Transport Aircraft and in a Reverberation Chamber,” IEEE Int. Symp. on EMC, Denver, CO, August 1998.

A-33.      Robinson, M.P.; Benson, T.M.; Christopoulos, C.; Dawson, J.F.; Ganley, M.D.; Marvin, A.C.; Porter, S.J.; & Thomas, D.W.P.; “Analytical Formulation for the Shielding Effectiveness of Enclosures with Apertures,” IEEE Transactions on Electromagnetic Compatibility, Vol. 40, pp 240-248, August 1998.

A-34.      Johnson, D.M.; Hatfield, M.O.; G.J. Freyer, G.J.; Slocum,M.B.; Ondrejka, A.R.; Johnk, R.T.; & Captain Thomas A. Loughry; “Phase II Demonstration Test Of The Electromagnetic Reverberation Characteristics Of A Large Transport Aircraft” Naval Surface Warfare Center, Dahlgren Division Technical Report, TR-97/84.

A-35.      Hatfield, M.O.; Freyer, G.J.; & Slocum, M.B.; “NASA Boeing 757 Cavity Field Variability Based on Boeing 757 and Boeing 707 Test Data,” NSWCDD/TR 97/25, Naval Surface Warfare Center, Dahlgren Division, Dahlgren, VA, March 1997.

A-36.      Freyer, G.J.; Hatfield, M.O.; Johnson, D.M.; & Slocum, M.B.; “Characterization of the Electromagnetic Environment in Aircraft Cavities Excited by Internal and External Sources,” Digital Avionics Systems Conference, Atlanta, GA, October 1996.

A-37.      Freyer, G.J.; Hatfield, M.O.; & Loughry, T.A.; “Cavity to Cavity Coupling Measurements in Commercial Aircraft and the Implications for On-Board Operation of Personal Electronic Devices,” Digital Avionics Systems Conference, Atlanta, GA, October 1996.

A-38.      Kempf, D.; “Electromagnetic Vulnerability Testing of Aircraft Using Mode-Stirred Techniques,” Digital Avionics Systems Conference, Atlanta, GA, October 1996.

A-39.      Schillinger, R. & Devereux, R.W.; “Electromagnetic Coupling Paths Evaluated from Inside a Commercial Aircraft,” Digital Avionics Systems Conference, Atlanta, GA, October 1996.

A-40.      Hughes, D.J.; DeSalvo, R.; et. al.; “TAB J-3 Electromagnetic Environmental Effects,” United States Air Force CT-43A 73-1149, Accident Investigation Board Report, USAF, June 1996.  (Briefed to President Clinton and V.P. Gore, White House Oval Office, 6/6/96)

A-41.      Goldblum, C.E. & Frazier, S.J.; “Overlaying LLCW and Mode-Stirred Data for Aircraft E3 Evaluation,” AMEREM ’96,Albuquerque, NM, May 1996.

A-42.      Hughes, D.J.; “Joint Ordnance E3 Risk Assessment Database Concept of Operations (JOERAD),” CONOPS PLAN, DoD Joint Spectrum Center, 15 March 1996.

A-43.      Freyer, G.J.; “Comparison of Boeing 757 Electromagnetic Cavity Characterization Data Using Band Limited White Gaussian Noise, CW with Mechanical Mode-Mixing, and CW frequency Step Excitations,” Proceedings of the Reverberation Chamber and Anechoic Chamber Operators Group Meeting, Dahlgren, VA, December 1995.

A-44.      Johnson, D.M.; “RF Coupling Measurements on Passenger Aircraft Avionics Exposed to Cavity-Mode Excitation,” Proceedings of the Reverberation Chamber and Anechoic Chamber Operators Group Meeting, Dahlgren, VA, December 1995.

A-45.      Kempf, D.; “EMV Testing of Aircraft: A Comparison of the Mode-Stirred and Standard Methods,” Proceedings of the Reverberation Chamber and Anechoic Chamber Operators Group Meeting, Dahlgren, VA, December 1995.

A-46.      Johnson, D.M.; Hatfield, M.O.; & Freyer, G.J.; “RF Coupling Measurements on Passenger Aircraft Avionics Exposed to Cavity-Mode Excitation,” Digital Avionics Systems Conference, Cambridge, MA, November 1995.

A-47.      Freyer, G.J.; Hatfield, M.O.; Loughry, T.A.; Johnk, R.; Ondrejka, A.; & Johnson, D.M.; “Shielding Effectiveness Measurements for a Large Commercial Aircraft”  IEEE Int. Symp. on EMC, Atlanta, GA, August 1995.

A-48.      Leach, R.D. & Alexander, M.B.; “Electronic Systems Failures and Anomalies Attributed to Electromagnetic Interference,” National Aeronautics and Space Administration, NASA Reference Publication 1374, MSFC, Alabama, July 1995.

A-49.      Tirkas, P.A.; Balanis, C.A.; Andrew, W.V.; & Barber, G.C.; “High Intensity Radiated Field (HIRF) Penetration in Helicopters,” IEEE Antennas and Propagation Society International Symposium, Newport Beach, CA, 18-23 June 1995.

A-50.      Rimbey, P. R. & Walen, D. B.; “Consistent Approach To Describing Aircraft HIRF Protection,” NASA 19950018921, 1 March 1995.

A-51.      Johnson, D.M.; Hatfield, M.O.; & Freyer, G.J.; “RF Coupling Measurements on Passenger Aircraft Avionics and Simulated Avionics Boxes Exposed to Cavity-Mode Excitation,” Seventh National Conference on High Power Microwave Technology, Naval Post Graduate School, Monterey, CA, October 1994.

A-52.      Freyer, G.J., Hatfield, M.O., Loughry, T.A. and Ondrejka, A.R., “External to Internal Cavity Coupling and Internal to Internal Cavity Coupling in Commercial Aircraft,” Seventh National Conference on High Power Microwave Technology, Naval Post Graduate School, Monterey, CA October 1994.

A-53.      Freyer, G.J. and Hatfield, M.O., “Aircraft Test Applications of Reverberation Chambers,”  IEEE Int. Symp. on EMC, Chicago, IL, August 1994.

A-54.      Hill, D.A., Crawford, M.L., Johnk, R.T., Ondrejka, A.R. and Camell, D.G., “Measurements of Shielding Effectiveness and Cavity Characteristics of Airplanes,” National Institute of Standards and Technology, Boulder, CO, NISTIR 5023, July 1994.

A-55.      Hatfield, M.O., Freyer, G.J., Johnson, D.M. and Farthing, C.L., “Demonstration Test of the Electromagnetic Reverberation Characteristics of a Transport Size Aircraft,” Naval Surface Warfare Center, Dahlgren Division, Dahlgren, VA; Report No. NSWCDD/TR-93/339, July 1994.

A-56.      Shooman, M.L., “A Study of Occurrence Rates of Electromagnetic Interference (EMI) to Aircraft With a Focus on HIRF (External) High Intensity Radiated Fields,”  NASA LaRC VA, April 1994.

A-57.      Freyer, G.J. and Hatfield, M.O., “Radiated Immunity Testing of Aircraft Systems Using Reverberation Chambers,” Third Australasian Instrumentation and Measurement Conference, AIM-TEC 94, Adelaide, Australia, April 1994.

A-58.      “Shuttle Flight Data and In-Flight Anomaly List,” NASA JSFC, JSC-19413, Revision T, change 1, August 1994.

A-59.      “Electromagnetic Interference,” Flight Standards and Safety Group of Douglas Aircraft Company, International Society of Air Safety Investigators (ISASI) forum, pp.14-15, March 1994.

A-60.      Sargent, N.B., “Development of a Proposed International Standard for Certification of Aircraft to High Intensity Radiated Fields (HIRF),” NASA 19940012047, 1994 International Pacific Air and Space Technology Conference, Singapore China ,14-18 Feb. 1994.

A-61.      Pearson, S. and Smith, D., “A Systems Engineering Approach to Electromagnetic Compatibility (EMC) Analysis for the Space Station Freedom Program,” AIAA 1^st Aerospace Sciences meeting and Exhibit, Reno, NV, 1993.

A-62.      Briere D. and Traverse, P., “AIRBUS A320/A330/A340 Electrical Flight Controls:  A Family of Fault-Tolerant Systems,” Aérospatiale, Toulouse, France, Proc. IEEE FTCS, pp. 616-623, 1993.

A-63.      Favre, C., “Fly-by-Wire for Commercial Aircraft – the Airbus Experience”, published in the International Journal of Control, special issue on Aircraft Flight Control, 1993.

A-64.      Scott, W., “F-117A Design Presented Avionics Challenges,” Aviation Week and Space Technology, pp. 43-44, February 1993.

A-65.       “Orbital Anomalies in Goddard Spacecraft for CY 1992,” prepared by Hernandez Engineering Company for GSFC, System Reliability and Safety Office, October 1993.

A-66.      Antoine, J.C. and Serres, A., “Use of Special Recovery Techniques for Parameters in the A320 Strasbourg Accident,” Bureau Enquêtes-Accidents, France, ISASI forum Proceedings, pp. 256-259, 1992.

A-67.      “SL-J Mission Electromagnetic Compatibility Analysis Report,” Teledyne Brown Engineers, July 1992.

A-68.      Elsen, W.G., “Orbital Anomalies in Goddard Spacecraft for CY 1991,” Assurance Requirements’ Office, Office of Flight Assurance, NASA GSFC, October 1992.

A-69.      Von Achen, W., “The Apache Helicopter:  An EMI Case History,” Compliance Engineering, Fall 1991.

A-70.      Todd, J.R., “Critical Digital Systems:  A Fly-by-Light Consideration,” Proceedings IEEE/AIAA 10^th Digital Avionics Conference, p. 471, Los Angeles, CA, October 14-17 1991.

A-71.      Clough, B.T., “On Upsets of Analog Portions of Digital Flight Control Systems Due to Electromagnetic Interference,” Wright Lab. US Air Force, SAE Technical Paper Series 912144, Aerospace Technology Conference and Exposition. Long Beach CA, 23-26 September 1991.

A-72.      Clough, B.T., “A Review of Digital Flight Control System Upsets Caused by Electromagnetic Interference,” Wright Lab. OH, White Paper, November 1990.

A-73.      Toon, J.J., “Metal Fibers and Fabrics as Shielding Materials for Composites, Missiles, and Airplanes,” Memcor, Div. Memtec America Corp., DeLand, Fl, IEEE, 1990.

A-74.      Lin, J-L, “Numerical Modeling Technique for Field-to-Cable Coupling Through Advanced Composite Material,” Boeing Military Airplanes, Seattle, WA, IEEE, 1990.

A-75.      Hämäläinen, S., “Go-Around Incident with Airbus 300,” Chief, Accident Investigation National Board of Aviation, Finland, ISASI forum Proceedings, pp. 72-73, 1990.

A-76.      Ford, R.T., “RPV Pioneer Aboard U.S.S. Iowa An EMI Case History,” 1990 International Symposium on Electromagnetic Compatibility,” Symposium Record, pp. 180-184, Washington, D.C., August 21-23 1990.

A-77.      Todd, J. R., Williams, T., Goldthorpe, S., Hay, J., Brennan, M., Sherman, B., Chen, J., Yount, L.J., Hess, R.F., Kravetz, J., “Fly-by-Light Technology Development Plan,” NASA LaRC 19920023534, 1 August 1990.

A-78.      Sorenson, D. and Fuller, G., “Understanding the Susceptibility of Digital Avionics to HERF,” 1990 International Symposium of Electromagnetic Compatibility, Symposium Record, pp. 207-211, Washington D.C., August 21-23 1990.

A-79.      Clough, B.T., “A Review of Digital Flight Control System Upsets Caused by Electromagnetic Interference,” USAF Wright Laboratory, White Paper, May 1990.

A-80.      Sorenson, D. and Fuller, G., “New Insight Into Understanding the Susceptibility of Digital Avionics to High Energy RF (HERF),” Proceeding IEEE/AIAA/NASA Ninth Digital Avionics Systems Conference, pp. 386-391.

A-81.      Belcastro, C., “Laboratory Test Methodology for Evaluating the Effects of Electromagnetic Disturbances on Fault-Tolerant Control Systems,” NASA LaRC 101665, November 1989.

A-82.      Pesta, A., “Draft Department of Defence Methodology Guidelines for High Power Microwave (HPM) Susceptibility Assessments,” USAF RADC, Rome NY, September 1989.

A-83.      Hess, R.F.; Yount, L.J.; Knoller, Henry; Masson, G.M.; & Larsen, W.E.;  “Sharing the Protection of Aircraft Electronic Systems Against the Effects of Nigh-Level Electromagnetic Environments Between Traditional Protection and System Architecture,” American Institute of Aeronautics and Astronautics, Inc. Symposium, pp. 294-307, 1988.

A-84.      Mordoff, K.P., “UH-60 Helicopters To Be Modified For Increased EMI Protection,” Aviation Week and Space Technology, pp. 75-77, October 10, 1988.

A-85.      Miles, Donna, “Black Hawk and EMI,” Soldiers Magazine, p. 49, July 1988.

A-86.       “Army Accelerating Hardening Of Black Hawk Against EMI,” Aviation Week and Space Technology, p. 31, 13 June 1988.

A-87.       “Review of the Army UH-60 (Black Hawk) Electromagnetic Environment Issues,” Inspector General, Department of Defense, 88-151, 1 June 1988.

A-88.      “Army Electromagnetic Effects (EME) Susceptibility Program,” HQ DA/SARD-TN Message 292100Z, July 1988.

A-89.      “Army Modifies UH-60s To Cut Electromagnetic Interference In Controls,” Aviation Week and Space Technology, p. 27, 16 November 1987.

A-90.      Clarke, C.A., and Larsen, W.E., “Aircraft Electromagnetic Compatibility,” U.S. Dept. of Transportation, FAA, Technical Center, Atlantic City, NJ, DOT/FAA/CT-86/40, DTIC AD-A189055, June 1987.

A-91.      Bean, J.L., “HERO Susceptibility of 2.75 inch FFAR:          Comparative Results Obtained From Mode-Stirred Chambers, Anechoic Chambers and Ground Plane Test Facilities,” IEEE IMTC Proceedings, p. 194, 1985.

A-92.      Catalano, G.T., and Clevenger, D., “Control Law Scaling and Estimation of Accuracy in a Microprocessor-Based Flight Control System,” Boeing, Seattle, WA, IEEE International Journal of Mini and Microcomputers, Vol. 7, No. 3, 1985.

A-93.      Zentner, J.C., “Aircraft EMC Problems and Their Relationship to Subsystem EMI Requirements,” ASD, EMC and Power Branch, WPAFB, Ohio, Proceedings IEEE, Vol. In National Aerospace and Electronics Conference, Dayton, OH, May 17, 1983.

A-94.      Rosenzweig, J., “Electromagnetic Interference in Aircraft,” Engineering Division, Israel Aircraft Industries, LOd, Israel, isasi Forum, pp. 70-71, #2, 1982.

A-95.      Leggett, J.F., “Electronic Interference with Airborne Navigation Systems,”  The Law Offices of James Francois Leggett, isasi Forum, pp. 30-39, #2, 1982.

A-96.      Wells, F.M., “Examination of Electrical Wiring and Equipment In Aircraft Accident Investigation,” Vanderbilt University, Nashville, TN, isasi Forum, pp. 6-9, #1, 1982.

A-97.      Birken, J.A., “Notebook of Electromagnetic Properties of Composite Materials Below 1 GHz,” NAVAIR AIR-518-7, September 1981.

A-98.      Ketterer, J.R., “The Navy F/A-18A Hornet Electromagnetic Compatibility Program,” IEEE EMC Symposium, August 1981.

A-99.      Bodnar, G.D., “Shielding Effectiveness Measurements on Conductive Plastics,” IEEE EMC Symposium, August 1979.

A-100.  McBrayer, P.R. & Lockie, Capt. Doug;  “The F-15 Air Superiority Fighter Electromagnetic Compatibility Program,” IEEE Electromagnetic Compatibility Symposium Record, San Francisco, CA, July 16-18, 1974.

A-101.  Hughes, D.J., “Development of a Cosite Analysis Model,” Proceedings of the Allied Radio Frequency Agency Second Biennial Symposium, Paper T‑9, NATO, Brussels, Belgium, 26-28 November 1973.

A-102.  “Electromagnetic Coupling to Aerospace Cables at Microwave Frequencies,” McDonnell Douglas Astronautics Company, Report ATN 73-003, November 1973.

APPENDIX B

ACN: 754696

 

Time / Day

 

Date : 200708

Local Time Of Day : 1201-1800

 

Place

 

Locale Reference.Airport : ZZZ.Airport

State Reference : US

Altitude.AGL.Single Value : 31000

 

Aircraft

Reference : X

ATC / Advisory.Center : ZZZ.ARTCC

Aircraft Operator : Air Carrier

Make Model Name : B737 Undifferentiated or Other Model

Crew Size.Number Of Crew : 2

Operating Under FAR Part : Part 121

Flight Plan : IFR

Mission : Passenger

Nav In Use : FMS Or FMC

Flight Phase : Climb

Flight Phase : Cruise

Airspace.Class A : ZZZ.A

 

Component

 

Aircraft Component : FMS/FMC

Aircraft Reference : X

Problem : Malfunctioning

 

Person

 

Reference : 1

Location Of Person.Aircraft : X

Reporter Organization : Air Carrier

Function.Flight Crew : Captain

Function.Flight Crew : Pilot Flying

Qualification.Flight Crew : Flight Instructor

Qualification.Flight Crew : Flight Engineer

Qualification.Flight Crew : Air Transport Pilot (ATP)

Experience.Flight Crew.Total : 16895

Experience.Flight Crew.Last 90 Days : 175

Experience.Flight Crew.Type : 8000

ASRS Report Number.Accession Number : 754696

Analyst Callback : Completed

 

Events

 

Anomaly.Aircraft Equipment Problem : Less Severe

Anomaly.Flight Deck / Cabin / Aircraft Event : Passenger Electronic Device

Anomaly.Deviation – Procedural : FAR

Anomaly.Deviation – Procedural : Published Material / Policy

Detector.Person : Flight Crew

Result.Aircraft : Equipment Problem Dissipated

 

Assessments

 

Contributing Factors / Situations : Aircraft

Contributing Factors / Situations : Human Factors

Primary Problem : Human Factors

 

Narrative: 1

 

I HAD THIS EXACT PROBLEM ABOUT 10 YEARS AGO UNDER THE SAME

CIRCUMSTANCES. THIS EVENT OCCURRED IN THE SAME TYPE OF ACFT, A B737

[NON GLASS]. DURING CLBOUT AND INITIAL CRUISE, I NOTICED THE NAV

RADIOS WERE IN AUTO UPDATE BUT THEY WERE NOT UPDATING. I THEN CHKED

THE FMC STATUS OF THE IRS’ AND FMC RADIO UPDATES. IT SHOWED DME

UPDATING FAIL. BEFORE I COMPLETED A POSITION SHIFT, I (CAPT) CALLED THE

FLT ATTENDANTS AND ASKED THEY DO A WALK THROUGH AND CHK FOR ANY

PED’S. THEY FOUND A PAX WITH A HANDHELD GPS, GARMIN NUVI MODEL 660.

ONCE THIS WAS TURNED OFF, THE FMC DME UPDATING WENT FROM FAIL TO ON

AND THE RADIOS STARTED TO UPDATE AGAIN. THE FLT CONTINUED AND LANDED

WITHOUT INCIDENT. THE ACFT WAS A B737 ‘CLASSIC’ MEANING ROUND DIALS

AND NOT EFIS. IT HAD TWO IRS’ WITH A SINGLE FMC BUT 2 FMC HEADSETS IN

THE COCKPIT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING

INFO: THE RPTR STATED THAT HE WAS CONCERNED THAT BECAUSE HE HAD

EXPERIENCED THIS SAME TYPE OF EVENT THREE TIMES IN THE LAST 10 YEARS

AND ALL IN THE B737 ACFT WITH THE FMS SYSTEM BUT NO GLASS, THAT THERE

MAY BE A COMMON THREAD. ONE PREVIOUS EVENT WAS CONFIRMED AS CAUSED

BY PORTABLE GPS AND THE OTHER MAY HAVE BEEN A CELL PHONE CALL MADE

JUST PRIOR TO LANDING. IN THE EVENT REPORTED HERE, THE DME FAILING TO

UPDATE WAS THE FIRST INDICATION. HE NOW FLIES THE B737 CLASSIC AS WELL

AS THE B737 NG’S. THE NG’S APPEAR TO BE MORE ELECTROMAGNETICALLY

ROBUST.

 

Synopsis

 

IN AN APPARENT PED INTERFERENCE EVENT, A PAX’S PORTABLE GARMIN GPS

MODEL NUVI 660 ALLEGEDLY INTEFERED WITH A B737 CLASSIC’S (NO GLASS)

DME NAVIGATION UPDATE FUNCTION.

APPENDIX C

Newsgroup Postings WRT B737 Rudders

Subject: Re: Pittsburgh/Co Springs

From: jhilt@nospam.online.no (John Hilt)

Date: Mon, Oct 27, 1997 00:40 EST

Message‑id: <34622894.6151580@news.sol.no>

On 25 Oct 1997 20:17:39 GMT, “Mark Rogers” <mmrogers@tcsn.net> wrote:

ATo buy into the Boeing pilot error scenario, you have to believe that a very experienced, professional crew, flying the airplane on the line, lost control at 6000 feet on a beautiful clear day, yet nothing is wrong with the airplane.@

After having read the Boeing submission to the NTSB, I’m overwhelmed by the all the work that has been done to produce this report.  Boeing has used 75,000 engineering hours over a 3 year period. (The amount of work done by their legal department is not stated.)

The 737 is such a stable aircraft, that it doesn’t even need a yaw damper, according to Boeing.  This is installed to improve ride comfort only.

But if this wonderfully stable aircraft encounters a wake turbulence from other 737 or the slightly heavier 727, the uncommanded aircraft movement is so violent, that pilots are startled, and typically overreact by applying too much correcting control input.

In my opinion, if a plane is thrown around by turbulence and flies like a bumble bee, it should be grounded.

The manufacturer will always try to blame the crew (remember ATR and the Simmons accident?).  Boeing has, however, redesigned the PCU, and all the airplanes will eventually be retrofitted.@

Why are major engineering changes necessary, when the problem is purely pilots that scare easily and can’t keep their calm?  :

From the report, page 37: http://www.boeing.com/news/techissues/

A. Operational Evidence

ASRS 293944 (Jan. 1995). A 737‑200 encountered wake turbulence from another 737 at 4,000 ft AGL. The pilot flying reported that upon encountering the turbulence, the nose abruptly pitched up 5 ‑ 10 degrees and the aircraft rolled 40 degrees to the left. The pilot disconnected the autopilot. The severity of this encounter surprised me…. Had I been distracted by looking at a chart or checking engine instruments, etc., I could have very easily ended up on my back, and this was from another 737! (60)

http://home.sol.no/jhilt
Subject: Re: NTSB Calls for Airbus Cockpit Changes

From: big-john@bigfoot.com.remove (Captain Bligh)

Date: Sat, Jan 31, 1998 02:27 EST

Message-id: 34d4c447.333255@news.sol.no

On Sun, 25 Jan 1998 21:53:32 – 0800, Hilton Goldstein <hilton@sgi.com> wrote:

>Damn, don’t you just hate those fatal rudder hardovers on 737s (since they’ve never found the problem, it may still exist)

Boeing has found the problem.  They’re not stupid, you know.

http://www.boeing.com/news/techissues/Usair427.pdf (page 79)

“Includes improved wire shielding and isolation to eliminate problems caused by electrical interference.”

Electrical interference (GSM cell phone) can upset (and even reverse) the rudder PCU via the electric part of it that is governed by the yaw damper.

A sudden interference induced movement, within the 3 degree rudder authority of the yaw damper, can totally upset the PCU (and not primarily upset or startle the pilot, as Boeing claims).

Switching off the yaw damper won’t help.  It will be too late…

 

Subject: Re: Another 737 rudder incident

From: jhilt@not.online.no (John Hilt)

Date: Fri, Mar 5, 1999 13:44 EST

 

G’day Sorcerer!

On 3 Mar 1999 03:29:24 -0000 Doug Hughes wrote:

>That’s not true.  Any number of other failures, including the failure of the PCU, can make the rudder move.  In fact, the catastrophic failures we’re talking about should not be possible due to a simple yaw amper failure, sinc the yaw damper authority is very limited (typically 5 deg, while full rudder travel is as much as 30 deg).

A full rudder deflection is theoretically only possible by using pedal input, and the pedals follow the rudder movement. On the 737, yaw damper deflection is limited to 3 degrees, and it does _not_ move the pedals.

If the yaw damper dies in flight, nothing much happens, except that the aircraft starts wagging it’s tail at cruise altitude.

But if the yaw damper control unit is jammed by signals from a GSM cell phone, or for any other reason starts “pumping”, the electric part of the PCU can upset the rest of the PCU.

The situation can be recovered at an early stage by switching off the yaw damper.  But if the PCU reverses and locks up, hydraulic power must be switched off to clear the lock up.

The procedure discussed is designed to avoid “crossover”, an airspeed below which full rudder deflection cannot be corrected by full aileron/spoiler.  Not all airlines have adopted it.

Most airlines don’t use the yaw damper below certain flight levels.  Get your hands on a check list and have a look for yourself.

– JH –        http://home.c2i.net/jhilt

 

A mid-air collision can really ruin your whole day.
Subject: Re: Another 737 rudder incident

From: “Gary Watson” <watsong@home.com>

Date: Fri, Mar 5, 1999 15:56 EST

There is an AD or mod that does some work on the PCU and associated wiring.  Spar Aerospace is carrying it out on Canadian’s 737-200s during the C/D checks.  I don’t know the details but it seems to be the latest attempt at resolving the longest ongoing snag on the 737-200.

 

Subject: Re: Another 737 rudder incident

From: jhilt@not.online.no (John Hilt)

Date: Sun, Mar 7, 1999 05:18 EST

G’day Randy Sweeney!

On Sat, 06 Mar 1999 03:46:40 GMT Doug Hughes wrote:

According to AvLeak… this latest 737 incident was on a ship with the latest PCU modification

Seems to me that the FAA is barking up the wrong tree.

Put a 737 on jacks, simulate flight mode, engage the yaw damper, and let someone walk down the isle using a cell phone.

Wiggle the yaw damper gyro slightly to simulate turbulence, and see what happens …

– JH –        http://home.c2i.net/jhilt

 

“Lose not thy airspeed, lest the ground cometh up and smithe thee.”

 

 

Subject: 737 Rudder Incidents

From: “Ralph Nesbitt” <rnesbitt@bellsouth.net>

Date: Sat, Mar 6, 1999 10:37 EST

Two incidents in last 2 weeks on A/C with redesigned rudder controls if these folks are to be believed http://awgnet.com/aviation/avi_air.htm .

Note mention of NTSB concerns raised by most recent incidents considering final hearings on past incident/crash schedueled for later in March.

Ralph Nesbitt

Some one said: To those for whom the bell has rung, may it never ring again.

 

 

Subject: Re: 737 Rudder Incidents

From: “Ralph Nesbitt” <rnesbitt@bellsouth.net>

Date: Sat, Mar 6, 1999 13:36 EST

NTSB prelimary report 737 rudder incident causing emergency landing at BWI.

http://www.ntsb.gov/aviation/DCA/99A040.htm

Ralph Nesbitt

Some one said: To those for whom the bell has rung, may it never ring again.
Subject: Re: Another 737 rudder incident

From: “John Gilmer” <gilmer@crosslink.net>

Date: Fri, Mar 12, 1999 08:33 EST

Well, an interesting question is:  If some “evil agent” took over the Yaw Damper and tried to do maximum damage to the A/C he would likely coordinate his efforts with the rudder movement.   It is not clear that just forcing the damper “hard over” is the worst case.  The worst case might be hard over, SLOWW return to normal, HARD OVER, SLOWWW return to normal.    This might confuse the pilots (otto and joe) enough to cause more problems than just the “hard over”.

A control loop failure MIGHT act like the “evil agent” described above.

 

Subject: Re: Another 737 rudder incident

From: “John Gilmer” <gilmer@crosslink.net>

Date: Fri, Mar 12, 1999 18:21 EST

How many of you “What if’s” were reality in http://www.open.gov.uk/aaib/gbgji.htm . Evil agents creating stray currents can cause a 737 to do strange things if these folks are to be believed. I wonder how many 737 E-Bays have been checked for leaks/indications of previous leaks onto/near rudder control connections after a rudder incident beside this one.

Ralph Nesbitt

 

Obviously, I don’t know.  BUT, many times in this NG the yaw “problem” was discounted on the basis that a worst-case failure would not cause the A/C to crash.   I just ask whether what they call the worst -case really is.

Elsewhere I asked whether the fact that the yaw sensing gyro is (I understand) near the A/C C.G., which place is closer to the passengers than much of the other electronics may make the electronics associated with it more subject to EMI from passengers’ electronics.

That’s all.

 

Subject: Re: Another 737 rudder incident

From: “Gary Watson” <watsong@home.com>

Date: Fri, Mar 12, 1999 21:32 EST

From spending a bit of time in 737 E bays, IIRC there is no hydraulics located in this area, the rudder control cables pass by overhead and the yaw damper and autopilot computers are right in front of your nose, but no fluids in this area. I know many of rudder glitches over the years have never been written up as they seem very transitory in nature. The crew will taxi up onto the line and say ” the rudder kicked on me once today and was fine for the next 4 legs.” or words to that effect and there re is nothing written into the log book. I am sure if all these occurrences were reported there would be a great deal of historical information regarding rudder problems but I don’t think anyone would be any further ahead. It is a puzzling snag because it is very intermittent.

BTW I agree with the earlier statements that the yaw damper does not have very much authority in the grand scheme of things on the 737. On the 707 however, its a different ball of wax. I recall an incident reported by Boeing a number of years ago of a S.American 707 dutch rolling from 90deg to 90deg because of a faulty yaw damper. The crew recovered but I am sure they had a hell of a ride.

Gary Watson

 

Subject: Re: Another 737 rudder incident

From: jhilt@offline.no (John Hilt)

Date: Sun, Mar 14, 1999 05:04 EST

Correct me if I’m wrong, but isn’t the rudder Linear Variable Displacement Transducer (LVDT) located in the cockpit, and the Yaw Damper Amplifier in the E&E comp.?

It is a puzzling snag because it is very intermittent. BTW I agree with the earlier statements that the yaw damper does not have very much authority in the grand scheme of things on the 737.

Consider this highly hypothetical scenario, (that explains it all):

The yaw damper system is jammed by radio signals, and starts making corrections within the 3 degree limit. No pedal movement.

The main part of the PCU picks up on this movement, (in some mysterious way that only God knows of), and slams the rudder to a hardover in the opposite directions as indicated by pedal movement.

An extremely confusing situation, and deadly at low level.

Ref. US Air 427.

 

 

Subject: Re: Another 737 rudder incident

From: Matt <Matt@brit101.demon.co.uk>

Date: Tue, Mar 16, 1999 11:03 EST

No, on the yaw damper actuator, which is in the vertical stab.

The yaw damper coupler is in the E/E bay, on the E1 rack.

The yaw damper operation doesn’t make the pedals move ever on a 737, since it’s a series system.

Well since the yaw damper actuator forms part of the rudder PCU, it’s highly likely that it will respond to a yaw damper signal, but not in the manner in which you describe.

A quick overview of the system could be called for.

The yaw damper system is totally independent.

It is the only automatic control of the rudder.

There is no autopilot input.

There’s a on/off switch on the overhead flying control panel with an engage light, a test switch and indicator on the forward panel.  The yaw damper operates off system B hydraulics.

The yaw damper coupler controls the system.

A rate gyro within the yaw damper coupler unit senses the a/c yawing motion.

It produces an AC signal which represents the direction and rate of the movement. This signal is filtered to allow the dutch roll characteristic frequency through. This prevents the system from trying to counter-act against deliberate turns and yaw. DADC 1 attenuates the signal as airspeed increases.

On the rudder PCU in the vertical stab, there are some bits for the yaw damper.

A shutoff valve, a transfer valve and the yaw damper actuator.

The shutoff valve allows hydraulic pressure to the transfer valve when the yaw damper has been switched on.  The transfer valve receives the signal from the coupler and ports hydraulic pressure to the actuator so that it moves as desired. That in turn operates the main rudder actuator and hence rudder.

A LVDT on the yaw damper actuator provides a position feedback signal so to cancel the command signal and return the yaw damper actuator to its central position.

Since the pedals don’t move, the indicator on the forward panel is the only means by which yaw damper operation can be monitored.

The yaw damper actuator’s movement is limited, and so cannot cause a rudder hardover no matter how hard it tries, since it operates the rudder actuator within this limit only.

Hope that helps a bit.

Matt

 

 

Subject: Re: US Air 427

From: “John Mazor” <mazorj@erols.com>

Date: Thu, Mar 25, 1999 12:58 EST

TMOliver wrote in message <36FA5919.DF4EE746@iamerica.net>…

>Bertie the Bunyip wrote:

>> Ralph Nesbitt wrote in message …

>> >NTSB votes 4-0 for rudder defect as probable cause, not pilot error.

Well then, once it’s done democratically, that must be it.

Soliciting response from both sides of the professional fence…

(Interestingly, El Bunyippo, un’piloto, tends to view the 737 “scenario”as an aviators’ problem, while some of the professionals from the ground side seem to be more inclined to lay the blame on Boeing.)

You think the news media and the public can be hard on pilots?

They’re amateurs when compared to a jury of their peers.

However, in this case, most pilots understand that there were no crew performance issues to speak of in any of the previous B737 accidents/incidents.

I suspect that Bertie’s just unconsciously exhibiting the normal pilot opinion that no one can fly it quite as good as he can.  😉

Is it possible that in the a/c’s current configuration that there is no

fix short of an entirely new fin/rudder/control assembly (a possibility

which, given the age of the design and the “startover” costs, might be cost-prohibitive)?

 

In the end it’s all going to depend on what’s your definition of “fixed” is (not to mention what “is” is), since the NTSB kicked this issue over to FAA to form a study group.  I suspect that this is why Boeing’s PR response was fairly low key — this is the major big-ticket $$$ item, and they know this prolongs their opportunity to water down, stall, or even officially eliminate any requirement to make major modifications.

I suspect that the Metrojet incident will make their job rather harder, since it involves an apparent rudder defect, but one that doesn’t quite fit the profile of the three previous examples.  IOW, there may be more problems requiring a more extensive redesign.

Which gives rise to a second question, whether Boeing (or “some folks” at Boeing) may have already reached this or similar conclusion and as in the case of a couple of examples in automobile business moved into ‘damage control’ mode?

IMHO, Boeing’s PR ops were a textbook example of low-key damage control.

Is it possible that training alone (and careful observance of flight

parameters and conditions) can lower/eliminate “risk” to “acceptable”

levels (I guess I fall somewhere between Paul Gooding and the

>”risk/benefit” actuaries, realizing that no design can be “faultless”,

>yet believing that design goals should seek fault-free perfection)?

 

Well, that’s exactly what we’ve already done from 427, even without waiting for yesterday’s findings, which just made official what everyone except Boeing has admitted for months to be the inevitable outcome.  However, get a rudder hardover in the first 20-30 seconds after rotation and see how long you have to resolve the problem!  (Watching the NTSB videos, it always startling, even when you know it Intellectually, to *experience* just how little time there was from onset to “Oh, shit!”.)  This cannot be resolved by training and performance, you’re gonna have to let the drawing board brigade and wrench turners have at it.

Pilots now have a specific and detailed procedure to follow, which allows them to isolate the nature of the rudder problem and deal with it.  FAA will recommend (but for no logical reason, will not yet mandate) a 10-knot increase in speeds for B737s at vulnerable phases of flight.  This doesn’t overcome the rudder problem per se, but it gives the crew enough control to take the time they need to run through the checklist and isolate the problem.

And for all this, we should never lose sight of the fact that the B737 has been an astonishingly safe and efficient workhorse for the industry.

>These questions relate to a potential, but not very attractive

>conclusion….this may be an “unfixable” problem, or one in which the

>selected fix may turn out to be (a) no fix at all or (b) the source of

>equally dangerous situations (which has happened before in the aviation

>business).

The “selected fix” will cure the rudder problem, or at least give pilots what they need to reduce rudder hardovers from a dead-certain killer to a fairly routine emergency to be dealt with, like engine failures and inop landing gear.

I would think that the main concern about major mods to the rudder would be the possibility of introducing new glitches along with the new hardware setup.  Kind of like the dilemma over

inspecting/replacing the aging wiring in various aircraft.  The minute you start pulling wire, you run the risk of damaging it.

But the real stumper here is Metrojet.

>>>>>

Subject: Re: US Air 427

From: “Ralph Nesbitt” <rnesbitt@bellsouth.net>

Date: Thu, Mar 25, 1999 15:49 EST

Soliciting response from both sides of the professional fence…  (Interestingly, El Bunyippo, un’piloto, tends to view the 737 “scenario” as an aviators’ problem, while some of the professionals from the ground side seem to be more inclined to lay the blame on Boeing.)

Is it possible that in the a/c’s current configuration that there is no fix short of an entirely new fin/rudder/control assembly (a possibility which, given the age of the design and the “startover” costs, might be cost-prohibitive)?

 

Which gives rise to a second question, whether Boeing (or “some folks” at Boeing) may have already reached this or similar conclusion and as in the case of a couple of examples in automobile business moved into ‘damage control’ mode?

 

Is it possible that training alone (and careful observance of flight parameters and conditions) can lower/eliminate “risk” to “acceptable” levels (I guess I fall somewhere between Paul Gooding and the

“risk/benefit” actuaries, realizing that no design can be “faultless”, yet believing that design goals should seek fault-free perfection)?

 

These qestions relate to a potential, but not very attractive conclusion….this may be an “unfixable” problem, or one in which the selected fix may turn out to be (a) no fix at all or (b) the source of

equally dangerous situations (which has happened before in the aviation business).

—

TMOliver, el pelon sinverguenza

From a small observatory overlooking McLennan Crossing

———————————————————————————————

A small amount of looking turns up the following 737 rudder incidents:

From NTSB 1990 to present:

02/12/99 http://www.ntsb.gov/aviation/DCA/99A041.htm

02/23/99 http://www.ntsb.gov/aviation/DCA/99A040.htm

02/23/99 http://www.ntsb.gov/aviation/DCA/99A045.htm

08/07/98 http://www.ntsb.gov/aviation/NYC/98A165.htm possible strongly referenced

08/13/98 http://www.ntsb.gov/aviation/DCA/98A080.htm

07/02/98 http://www.ntsb.gov/aviation/DCA/98A070.htm

03/11/98 http://www.ntsb.gov/aviation/ANC/98A026.htm

06/09/96 http://www.ntsb.gov/aviation/DCA/96A061.htm

05/14/96 http://www.ntsb.gov/aviation/NYC/96A106.htm

08/25/95 http://www.ntsb.gov/aviation/MIA/95A214.htm uncommanded roll due electrical problem with auto-pilot

09/08/94 http://www.ntsb.gov/events/usair427/items.htm

04/23/93 http://www.ntsb.gov/aviation/DEN/93A044.htm probably wake turbulence

03/03/91 http://www.ntsb.gov/aviation/DCA/91A023.htm UAL at Colorado Springs, CO.

 

From Britian’s Air Accident Investigation Board:

http://www.open.gov.uk/aaib/gbgji.htm

 

There are 2 737 control incidents due Auto Pilot channel failure/overload.

There is one 737 random Aileron incident due electrical problems. There are 2 737 unexplained Total Power Failure incidents on approach.

 

The British folks make a strong case for electrical problems originating in the E-Bay. There are various references in these reports to incidents occurring after an auto-pilot change of mode, setting change, etc.

 

Apparently disengaging the auto-pilot and other automated controls is part of recovery procedures which have been effective in recovery from such incidents.

 

Perhaps a “Spurious Electrical Gremlin” is causing conflicts in/among/with the various electrical control mechanisms under certain conditions causing these incidents.

 

Some where in all the above there should be a situation common to all incidents at/near onset. The problem may be control of automated control inputs under certain conditions.

 

Ralph Nesbitt

 

>>>>>

 

Subject: 737 rudder ??????????

From: acesan8s2@aol.com (Acesan8s2)

Date: Tue, May 11, 1999 05:30 EDT

 

NTSB Identification: LAX99SA147

 

Scheduled 14 CFR 121 operation of UNITED AIRLINES, INC. (D.B.A. UNITED AIRLINES)

Incident occurred APR-13-99 at SANTA BARBARA, CA

Aircraft: Boeing 737-300, registration: N394UA

Injuries: 69 Uninjured.

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

 

On April 13, 1999, at 1915 hours Pacific daylight time, a Boeing 737-300, N394UA, experienced an uncommanded roll to the left during level cruise at flight level 310, 25 miles northwest of Santa Barbara, California. The aircraft was operated by United Airlines, Inc., as Flight 2058, a regularly scheduled

domestic passenger flight en route from Los Angeles to San Francisco, California. The airplane was not damaged and returned to Los Angeles International Airport, where it made an uneventful landing at 1938. The 2-flight crew, 3 flight attendants, and 64 passengers were not injured. The flight was being conducted under 14 CFR Part 121 and an IFR flight plan was filed. Visual meteorological conditions prevailed at the time of the incident. The crew experienced “light chop” at flight level 310 and was going to request a descent. The unexpected roll was described as a “rudder kick, a sharp quick uncommanded kick to the left.” The autopilot was on during the 20- to 30-degree roll excursion to the left.

 

>>>>>

 

NTSB Identification: DCA99SA041

 

 

Scheduled 14 CFR 121 operation of UNITED AIRLINES (D.B.A. UNITED AIRLINES)

Incident occurred FEB-12-99 at SEATTLE, WA

Aircraft: Boeing 737-300, registration: UNK

Injuries: 40 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

During taxi-out controls check the flight crew noticed that the rudder pedals were sluggish or stiff. The airplane returned to the gate and maintenance verified that the pedals did not respond normally. The main rudder PCU was replaced and the airplane returned to service.

>>>>>

NTSB Identification: DCA99SA040

Scheduled 14 CFR 121 operation of METROJET (D.B.A. METROJET/USAIRWAYS)

Incident occurred FEB-23-99 at SALISBURY, MD

Aircraft: Boeing 737-200, registration: N282AU

Injuries: 126 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On February 23, 1999, a Boeing 737-200, Registration N282AU, operated as Metorjet flight 2710 made an emergency landing at Baltimore-Washington International Airport due to a flight control problem. The flight crew reported at while at cruise near Salisbury, Maryland, the airplane began to roll to the left while the heading did not change. After disconnecting the autopilot they noticed that the right rudder pedal was forward of neutral and that pressure on the left rudder pedal would not move the rudder. After turning on the standby rudder, the rudder pedals centered.

>>>>>

NTSB Identification: DCA99SA04

Scheduled 14 CFR 121 operation of USAIRWAYS (D.B.A. USAIRWAYS)

Incident occurred FEB-23-99 at MONTREAL

Aircraft: Boeing 737-200, registration: N262AU

Injuries: 50 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On February 23, 1999, a USAirways B-737-200, registration N262AU, experienced a uncommanded rudder movement shortly after departure from Montreal, Canada. The flightcrew disconnected the yaw damper and the problem subsided.

>>>>>

NTSB Identification: ATL99SA050

Scheduled 14 CFR 121 operation of DELTA AIR LINES, INC.

Incident occurred MAR-12-99 at ATLANTA, GA

Aircraft: Boeing 737-247, registration: N382DL

Injuries: 110 Uninjured

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On March 12, 1999, at 0915 eastern standard time, a Delta Airlines Boeing 737-247, N382DL, operating as Delta Flight 720, experienced a two second hard rudder kick, during cruise flight, while enroute to Atlanta, Georgia. The airplane was operated by Delta Airlines, Inc., under the provision of 14 CFR Part 121, and instrument flight rules. Visual meteorological conditions prevailed and an IFR flight plan was filed. The pilot, first officer, one jump-seat occupant, four flight attendants, and 103 passengers were not injured, and the aircraft was not damaged. The flight originated from Shreveport, Louisiana; the exact departure time was not determined. According to Delta, the aircraft experienced a two second uncommanded yaw to the right. The situation corrected itself with no additional problems. The remainder of the flight was uneventful. The airplane landed at Atlanta without further incident. The flight data recorder and the power control unit have been removed from the aircraft for further examination.

 

>>>>>

 

NTSB Identification: LAX99SA144

Scheduled 14 CFR 121 operation of UNITED AIRLINES INCORPORATED (D.B.A. UNITED AIRLINES)

Incident occurred APR-10-99 at LAS VEGAS, NV

Aircraft: Boeing 737-300, registration: N387UA

Injuries: 140 Uninjured.

 

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

 

On April 10, 1999, at 1317 hours Pacific daylight time, a Boeing 737-300, N387UA, aborted the takeoff roll at McCarren Field, Las Vegas, Nevada, due to an uncommanded yaw. The aircraft was operated by United Airlines, Inc., as Flight 2559, a regularly scheduled domestic passenger flight to Los Angeles, California. The aircraft was not damaged, and after the yaw coupler was replaced as a precautionary measure, the aircraft continued on to its original destination. The flight crew of 2, one jump seat rider, 3 flight attendants, and 134 passengers were not injured. The flight was being conducted under 14 CFR Part 121 and an IFR flight plan was filed. Visual meteorological conditions prevailed at the time of the incident. According to the pilots, as the aircraft passed through 120 – 130 knots in the ground roll, the airplane yawed slightly. The crew indicated that they had no unusual cockpit indications prior to the yaw event. After the airplane returned to the gate, the aircraft was delayed at Las Vegas for approximately 5 hours and 10 minutes. After the maintenance delay, the aircraft departed for Los Angeles, and landed at 1929. After the aircraft landed at Los Angeles, a mechanic for the United Airlines noticed that the nose gear made an “unusual bump and rattle” during turning while the aircraft was being taxied to the hanger. A ferry permit was obtained and the aircraft was ferried from Los Angeles to their maintenance base in San Francisco, California. After the airplane arrived in San Francisco, the nose landing gear trunion bearings were replaced.

 

>>>>>

 

NTSB Identification: LAX99SA147

 

 

Scheduled 14 CFR 121 operation of UNITED AIRLINES, INC. (D.B.A. UNITED AIRLINES)

Incident occurred APR-13-99 at SANTA BARBARA, CA

Aircraft: Boeing 737-300, registration: N394UA

Injuries: 69 Uninjured.

 

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

 

On April 13, 1999, at 1915 hours Pacific daylight time, a Boeing 737-300, N394UA, experienced an uncommanded roll to the left during level cruise at flight level 310, 25 miles northwest of Santa Barbara, California. The aircraft was operated by United Airlines, Inc., as Flight 2058, a regularly scheduled domestic passenger flight en route from Los Angeles to San Francisco, California. The airplane was not damaged and returned to Los Angeles International Airport, where it made an uneventful landing at 1938. The 2-flight crew, 3 flight attendants, and 64 passengers were not injured. The flight was being conducted under 14 CFR Part 121 and an IFR flight plan was filed. Visual meteorological conditions prevailed at the time of the incident. The crew experienced “light chop” at flight level 310 and was going to request a descent. The unexpected roll was described as a “rudder kick, a sharp quick uncommanded kick to the left.” The autopilot was on during the 20- to 30-degree roll excursion to the left.

 

>>>>>

 

NTSB Identification: DCA99WA078

 

Scheduled 14 CFR 129 operation of SAS

Incident occurred AUG-26-99 at DURBAN S. AFRICA
Aircraft: Boeing 737-200, registration: UNK
Injuries: 5 Uninjured.

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
Airplane experienced an reported uncommanded yaw.

 

>>>>>

 

NTSB Identification: MIA99SA273. The docket is stored in the (offline) NTSB Imaging System.

 

Scheduled 14 CFR 121 operation of DELTA AIR LINES, INC.

Incident occurred SEP-28-99 at PONTE VEDRA BCH, FL
Aircraft: Boeing 737-232, registration: N310DA
Injuries: 38 Uninjured.

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
On September 28, 1999, about 2236 eastern daylight time, a Boeing 737-232, N310DA, registered to Wilmington Trust Company and operated by Delta Air Lines, Inc., as Delta Express Flight 2527, scheduled domestic passenger service from Washington, D.C., to Orlando, Florida, experienced an uncommanded yaw and roll while in cruise flight at 31,000 feet near Ponte Vedra Beach, Florida. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The aircraft was not damaged and the airline transport-rated captain, first officer, 3 flight attendants, and 33 passengers were not injured. The flight originated from Washington Dulles International Airport, Washington, D.C., the same day, about 2109. The flightcrew reported to Delta Air Lines, Inc., that while en route at 31,000 feet, 65 nautical miles north of the Ormond Beach VOR, the aircraft suddenly yawed and then rolled hard to the left. They applied 40-50 degrees of control wheel input back to the right, and deactivated the yaw dampener. The aircraft returned to normal flight and they continued to the destination with the yaw dampener deactivated. Delta Air Lines, Inc. personnel stated that after arrival in Orlando, Florida, the yaw dampener coupler and rudder power control unit (PCU) were replaced. The aircraft rudder and yaw dampener system tested normal after this and the aircraft was returned to service. The digital flight data recorder (DFDR) was removed from the aircraft after the incident for readout. The removed yaw dampener coupler and rudder PCU will be tested and disassembled.

 

>>>>>

 

NTSB Identification: DCA00SA013

 

Scheduled 14 CFR 121 operation of AIRTRAN, INC

Incident occurred DEC-16-99 at ATLANTA, GA
Aircraft: Boeing 737-200, registration:
Injuries:

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
On December 16, 1999, at about 0810 EST, AirTran Flight 801, a Boeing 737-200, experienced uncommanded rolling/yawing moments in flight, and landed at Hartsfield International Airport, Atlanta, GA without further incident.

 

>>>>>

 

Subject: Re: Cell Phones in Flight??

From: jhilt@offline.no (John Hilt)

Date: Sat, Jan 29, 2000 04:41 EST

Message-id: <3892b42c.4815110@news1.online.no>

 

G’day all!

On Mon, 17 Jan 2000 22:17:58 -0500 paradisiac wrote:

 

>>http://www.pulitzer.org/year/1997/beat-reporting/works/737-1/

>What an uninformed dumb***.

Yeah, right. If you ever get the chance, put a 737 on jacks and simulate flight mode with the yaw damper engaged.

Put one cell phone in the E&E compartment, and another one behind the aft bulkhead. Simulate turbulence by wiggling the gyros. Make calls to the cell phones, and watch that rudder start kickin’ away …

 

Not a realistic in-flight situation, but it should prove my point.

 

—

_/_/_/_/    http://home.c2i.net/jhilt

 

Smith & Wesson, the original point and click interface.

 

APPENDIX D

ACN: 440434

Time / Day

Date : 199906
Local Time Of Day : 1801-2400

Place

Locale Reference.Airport : ZZZ.Airport
State Reference : US
Relative Position.Distance.Nautical Miles : 8

Environment

Flight Conditions : VMC
Weather Elements / Visibility.Visibility : 20
Light : Night

Aircraft

Reference : X
ATC / Advisory.TRACON : ZZZ.TRACON
Aircraft Operator : Air Carrier
Make Model Name : B737-300
Crew Size.Number Of Crew : 2
Operating Under FAR Part : Part 121
Flight Plan : IFR
Mission : Passenger
Nav In Use : FMS Or FMC
Nav In Use.Localizer/Glideslope/ILS : 26
Flight Phase : Initial Approach
Route In Use : Visual Approach
Airspace.Class B : ZZZ.B

Component

Aircraft Component : Aeroplane Flight Control
Aircraft Reference : X
Problem : Malfunctioning

Person : 1

Reference : 1
Location Of Person.Aircraft : X
Reporter Organization : Air Carrier
Function.Flight Crew : Pilot Flying
Function.Flight Crew : Captain
Qualification.Flight Crew : Commercial
Qualification.Flight Crew : Air Transport Pilot (ATP)
Qualification.Flight Crew : Multiengine
Qualification.Flight Crew : Flight Instructor
Qualification.Flight Crew : Instrument
Qualification.Flight Crew : Flight Engineer
Experience.Flight Crew.Total : 20000
Experience.Flight Crew.Last 90 Days : 120
Experience.Flight Crew.Type : 120
ASRS Report Number.Accession Number : 440434
Analyst Callback : Attempted

Person : 2

Reference : 2
Location Of Person.Aircraft : X
Reporter Organization : Air Carrier
Function.Flight Crew : Pilot Not Flying
Function.Flight Crew : First Officer
Qualification.Flight Crew : Instrument
Qualification.Flight Crew : Multiengine
Qualification.Flight Crew : Commercial

Person : 3

Reference : 3
Location Of Person.Facility : ZZZ.TRACON
Reporter Organization : Government
Function.Air Traffic Control : Approach
Qualification.Air Traffic Control : Fully Certified

Events

Anomaly.Aircraft Equipment Problem : Critical
Anomaly.Inflight Event / Encounter : Loss Of Aircraft Control
Detector.Person : Flight Crew
Result.General : Maintenance Action
Result.Flight Crew : Regained Aircraft Control
Result.Flight Crew : Landed As Precaution

Assessments

Contributing Factors / Situations : Aircraft
Primary Problem : Aircraft

Narrative: 1

UNCOMMANDED ROLL/YAW. I PICKED UP ACFT (A B737-300) AT ZZZ1 FOR THE FIRST LEG OF A 2 LEG DAY TO ZZZ3. THE CAPT THAT BROUGHT THE AIRPLANE IN HAD NO COMPLAINTS NOR WERE THERE ANY LOG WRITE-UPS. WE HAD 1 1/2 HRS GND HOLD AT ZZZ1 AT THE GATE DUE TO TFC AND WX AT ZZZ2. FO FLEW THE LEG FROM ZZZ1 TO ZZZ2. EVERYTHING WENT NORMAL AND ALL APPEARED TO BE OK WITH THE ACFT. I DID NOTICE AND MENTIONED THAT MY LOC DID NOT PICK UP A SIGNAL UNTIL 3 OR 4 MINS AFTER HIS DID. ON THE GND AT ZZZ2, INSTEAD OF CHANGING ACFT, WE WERE TOLD TO KEEP THIS ACFT FOR THE LEG TO ZZZ3. I FLEW THE LEG FROM ZZZ2 TO ZZZ3 WITH THE ACFT FLYING NORMAL DURING TKOF, CLBOUT AND LEVELOFF. IT WAS A NORMAL LEG FLOWN AT THE FLT PLANNED ALT OF FL310. DSCNT WAS NORMAL WITH NO ERRATIC PERFORMANCE. TFC WAS LIGHT AND WE WERE CLRED FOR THE ILS. THERE WERE NO ACFT IN FRONT OF US WHILE WE WERE ON THE APCH AND THE WINDS WERE LIGHT TO CALM. THIS BEING MY FIRST TIME INTO ZZZ3, I PURPOSELY SLOWED DOWN AND STARTED CONFIGURING THE ACFT A LITTLE EARLY. I CALLED FOR GEAR DOWN AND FLAPS 15 DEGS AT THE 11 DME POINT FROM THE RWY. I WAS ON THE GS HAND FLYING THE ACFT WITH THE AUTOTHROTTLES ENGAGED. BUGGING DOWN TO 150 KTS WITH FLAPS 15 DEGS, I CALLED FOR FLAPS 25 DEGS AND 30 DEGS AND BUGGED DOWN TO BUG SPD +5 KTS. THE AUTOTHROTTLES RETARDED THE THROTTLES TO IDLE (AT 8 DME FROM FIELD). WHEN THE SPD APCHED BUG THE THROTTLES ADVANCED TO MAINTAIN THE DIALED IN SPD WHICH WAS AT 134 KTS. AT THIS POINT THE ACFT ROLLED R THEN L AT 10 DEGS, 2-3 TIMES AND THERE SEEMED TO BE SOME YAW FIRST R THEN L. I DISENGAGED THE AUTOTHROTTLES AND SAID TO THE FO, ‘I GUESS THAT WAS ASYMMETRICAL THRUST (SPOOL UP).’ WHAT WAS SO NOTICEABLE ABOUT THE EVENT WAS THAT WHEN I TRIED TO COUNTERACT THE CONDITIONS THE CTLS WERE VERY SOFT TO ALMOST NON EXISTENT. I CONTINUED ON THE APCH WITH THE RWY IN SIGHT AND AFTER SAY 10-20 SECONDS WITH SPD AND DSCNT STABILIZED, THE ACFT STARTED THE UNCOMMANDED ROLLING MOTION AGAIN, AGAIN THE FLT CTLS DID NOT INITIALLY STOP NOR CORRECT THE ACTION. AGAIN THE CTLS DID NOT APPEAR TO BE RESPONDING TO INPUTS NORMALLY. IT TOOK EXAGGERATED L AILERON TO STOP THE ROLLS TO THE R AND VICE VERSA, WITH THE RUDDER FEELING SOFT AND MUSHY AND NOT RESPONDING TO INPUTS. ONCE AGAIN I REGAINED CTL. (AT THE ONSET OF THE SECOND SERIES OF ROLLS I CALLED FOR YAW DAMPER OFF AND AT THE SAME TIME REACHED UP AND TURNED IT OFF.) AT THIS POINT I ASKED WHAT WERE THE WINDS FROM PAGE 2 OF THE PROGRESS HDG IN THE FMC. HE SAID ‘CALM.’ ALL APPROPRIATE CHKLISTS HAD BEEN CALLED FOR AND COMPLETED I MIGHT ADD. FOR A SHORT TIME — SAY 5-10 SECONDS — CTL INPUTS APPEARED TO RETURN TO NORMAL, AND THEN FROM SAY 500-800 FT OUT THEY APPEARED TO BE GRADUALLY JUST FADING OUT WITH THE ACFT CONTINUING THE ROLL ACTION WITH VERY LITTLE RUDDER RESPONSE. IN ANY NORMAL ACFT I WOULD HAVE GONE AROUND AT THIS POINT, BUT AT THIS POINT I DID NOT FEEL THE AIRPLANE WAS AIRWORTHY. I DECIDED I HAD TO LAND EVEN IF IT MEANT A HARD LNDG DUE TO LACK OF NORMAL CTL INPUTS. I HAD MARGINAL RUDDER AND AILERON CTL AT TOUCHDOWN. I USED NOSE-UP TRIM AT FLARE AND IT GAVE ME A NORMAL LNDG. FROM THE 500 FT POINT ON DOWN, I CONFIRMED SYMMETRICAL THRUST, NORMAL SINK AND REALIZED THAT I WOULD HAVE TO ACCEPT DRIFT AT TOUCHDOWN RATHER THAN HAVE AN EXAGGERATED AILERON INPUT IN AND HAVE THE CTLS RETURN TO NORMAL AND HIT AN ENG OR WINGTIP. ROLLOUT AND REVERSE APPEARED TO BE NORMAL. TAXI IN WAS NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CREW WAS ON THE SECOND LEG OF THE DAY WITH THE ACFT. ON APCH, WITH FLAPS 15 DEGS AND APPROX 150 KTS, THE ACFT BEGAN AN UNCOMMANDED YAW AND ROLL. AT THIS TIME THE ROLLING MOTION WAS ABOUT 10 DEGS FROM SIDE-TO-SIDE AND BECOMING DIVERGENT. THE CREW DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES, NO CHANGE. THE CAPT THEN VERIFIED THAT THE ENGS WERE NOT SURGING BY OBSERVING NO CHANGE IN N1 OR FUEL FLOW. NEXT, THE YAW DAMPER WAS TURNED OFF, AGAIN NO CHANGE. HYD SYS ‘A’ AND ‘B’ WERE VERIFIED AS NORMAL. ALL THIS TIME THE CAPT WAS ATT

Synopsis

B737 CREW HAD UNCOMMANDED CTL INPUT AND UNRESPONSIVE FLT CTLS ON FINAL APCH.

APPENDIX E

1212 Finneans Run

Arnold, MD 21012-1876

November 14, 2000

Member George W. Black, Jr.

National Transportation Safety Board

490 L’Enfant Plaza, S.W.

Washington, DC 20594

Subject:  Aircraft Yaw Upsets and Safety

How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?  A Study in Scarlet, Sir Arthur Conan Doyle, 1887.

Mr. Black,

Reading the summary of findings and recommendations from the FAA’s recent 737 Flight Controls Engineering Test and Evaluation Board report would lead the public to believe that the initial, classic, and next-generation Boeing 737 rudder designs are unsafe.  This ignores the fact that there have been no yaw upset events with the next-generation B737s.  The suggested redesign with two independent hydraulic valves is long overdue but will take at least four years.  Should all B737s be grounded until fixed?  The answer to this hypothetical question is “Of course not.”

Boeing’s B737 chief engineer for safety and certification, Allen Bailey, was quoted on page 22 of the 18 September 2000 issue of Aviation Week & Space Technology:  “This airplane has been fixed”.

The data are now available to allow the public to be informed that Mr. Bailey’s statement is most likely correct.  The data point to an upset due to an error signal at the LVDT input to the old initial/classic B737 analog yaw damper coupler, not to a sticking and over travel in the dual-concentric hydraulic valve.

The many points suggested from the available data require that this letter be quite long.  The points include:

• The 30-year history of initial/classic B737 yaw upset rates of three per month has subsided to zero since late summer 2000.
• The Boeing statements that the yaw damper does not have enough control authority to cause upsets (or accidents) and can be easily overcome by the crew merely stepping on the rudder pedals appears to be negated by the experiences of Eastwinds B737-200 N221US crews during May/June 1996.  The Boeing material in NTSB DCA94MA076, Exhibit 9X-I does not correlate with the Eastwinds experiences.  N221US was receiving an error signal to the yaw damper coupler due to an improperly aligned LVDT.  It is also doubtful that B737 flight simulator tests included error signals input to the yaw damper coupler and a resultant 120-second 3-degree correction to any rudder inputs made by the crew with the yaw damper engaged.  This is a key point for initial/classic B737s as to the impact of yaw damper upsets and attempts to recover from them.
• The 1960s-era initial/classic B737 yaw damper coupler was designed with an overdamped integrator (see NTSB DCA94MA076, Exhibit 9X-A, page 95, last paragraph).
• The NTSB recommended addition of the LVDT input signal to the yaw damper coupler to the parameters monitored by expanded B737 FDRs (although it is doubtful that the FDR recording speed would be adequate for the error signal of interest).  This implies that you also suspected an error signal.
• Wire bundle shield grounding integrity is imperative to prevent coupling of EMI to the long cable running through the passenger cabin from the rudder PCU LVDT to the forward-located yaw damper coupler.  Comparison of yaw upset events with aircraft tail numbers reveals some repeatability.  The USAF versions of the same aircraft have suffered no yaw upsets.  The USAF aircraft are excellently maintained.  The potential for a wire-shield-ground maintenance problem needs to be investigated as part of the FAA’s aging wiring study.  Wire bundle over-braid shields are often ineffective at the ultrahigh frequencies used by cellular telephones.  The initial/classic B737 yaw damper coupler wire shielding had to be improved to prevent yaw damper EMI from on-board high-frequency transmissions at much lower frequencies where shielding is usually effective.  See Boeing Service Bulletin 737-22-1112 “EMI Effects on Yaw Damper” of June 18, 1992.  Also see page 82, bottom bullet in left column, Appendix F, Boeing-Recommended Design Changes, of the Boeing US Air 427 submission (this is item 595 on the NTSB’s CD ROM):  “Includes improved wire shielding and isolation to eliminate problems caused by electrical interference.”
• Circuitry, as used in yaw damper couplers, has a long history of EMI susceptibility.  Early designs were qualified to radiated susceptibility levels of only 0.1 Volt/meter or less where modern designs have to be qualified to much higher levels (20 V/m).  Yaw upsets are prevalent on older aircraft equipped with early, non-EMI hardened avionics.  The Aileron-Rudder Interconnect (ARI) amplifier used on the F-4 Phantom II aircraft was EMI susceptible and had to be fixed.  The ARI amplifier is of the same generation (35 years ago) as the initial/classic B737 yaw damper coupler and is of a similar design.  I briefed this ARI amplifier EMI susceptibility characteristic to the NTSB staff during a February 1, 1996 Brown-Bag presentation on Electromagnetic Environmental Effects (E3) attended by Vice Chairman Francis and about 20 others from your staff.  Many other types of aircraft EMI susceptibilities were overviewed during that briefing with a resulting recommendation, from me, that E3 be included in every NTSB safety investigation (including rail).  This advice has slowly been heeded by your board, but only after the public writings of Dr. Elaine Scarry of Harvard.  Her E3 credentials are far less substantial than mine.
• NTSB conclusions stating that EMI was considered and found to be non contributing for US Air 427 & United 585 are not supported in the published material.
• Electronic amplifiers, when over driven into nonlinearity or saturation, become detectors rather than amplifiers. This was included in my 2/1/96 Brown-Bag Brief to the NTSB staff along with some nonlinear theory.  I could tell by eye contact that the theory was not understood by the audience.  The EMI impact would be the same as a bad amplifier.  There were five reported yaw episodes with Air France B737-300 F-GHVM during 1993 that were eventually traced to a bad amplifier in the yaw damper coupler.  EMI impact would be similar to these events.
• The airplanes were trying to tell you something, and the NTSB technical staff didn’t know what.  The yaw damper mechanical adder is directly connected to the torque tube in the B737 vertical stabilizer.  The rudder pedal cables also connect to the torque tube.
• We frequent fliers have often heard ringing cell phones in overhead luggage racks at critical times during flights.  I heard one ringing at about the middle marker point on the 27 October 2000 SWA 2180 approach to Houston/Hobby.  It was on a next-generation B737-700.  I heard another on the return SWA 1868 on the 29^th when taxing from the Jackson, MS gate to the runway.  An alert flight attendant also heard it and made a PA announcement threatening to abort the flight unless the cell phone was disabled.  This was on a classic B737-300.
• Thousands of tests of the dual-concentric hydraulic valve have shown only one or two cases of sticking and over travel.  The redesigned valve from the next-generation B737s didn’t help MetroJet 2710 (and others?) when incorporated by the AD into the initial/classic B737s.

 

I suggested a straightforward fault tree analysis to resolve this mystery in a 24 October 2000 e-mail to Mr. Scott Warren of your technical air safety staff.  If additional validation is required, the NASA/Langley HIRF Laboratory staff (Mr. Jay Ely and Dr. Celeste Belcastro) have been kept informed of the above findings and can be tasked to test the old initial/classic B737 yaw damper coupler for EMI susceptibility from the internal and external electromagnetic environments.

 

The NTSB has closed the US Air 427/United 585 investigations and turned the investigation and redesign issues over to the FAA.  However, many of the points listed above apply to other older aircraft types.  There have been reported yaw upset events with A300s (AA 916 at Miami on 5/11/99), DC-9s, MD‑80s, DC-10s, Gulf Stream IVs, B727s, and others.  Fortunately, the yaw damper coupler integrators for these other aircraft have resistor-capacitor time constants much shorter than the overdamped (120 seconds) initial/classic B737 design.  This allows quick recovery but is still a safety issue.  A recent (10/1/00) AA B727 yaw upset event resulted in declaration of an emergency, fuel dumping, and return to the Miami airport.

If/when it can be confirmed that the early yaw damper coupler designs are EMI susceptible, the safety recommendations are obvious:

• For twin-panel rudder aircraft, separate the wire routings between the rudders and the two yaw damper couplers into different shielded wire bundles and route each separately through the cabin.  This way, an error signal from EMI will be coupled to only one of the two yaw dampers and allow the remaining yaw damper and panel to correct the upset.  Bond the wire shield to structure at each wire bundle discontinuity using very short pigtails or grounded connector backshells.
• Add inexpensive ferrite beads at the yaw damper coupler amplifier input to knock down the EMI signal.  These beads are an effective radio frequency low pass filter.
• Reconsider grandfather certification.  This issue was discussed during your US Air 427 Sunshine Law report review.
• Study the impact of poorly bonded wire shield grounds as part of the aging wiring study.
• Passengers must be made aware that the safety announcements concerning portable electronic device use are not to be trivialized.  The July House Aviation Subcommittee hearing only scratched the surface of this BIG problem.  The passengers are an important part of the air safety solution.

 

I have a large notebook filled with supporting material for this EMI-susceptibility theory.  I am available to discuss it with objective members of your technical staff who can “think outside the box.”  I’ve tried in the past three years to discuss this with seven members of your technical support staff.  All have accepted the position that the yaw damper upsets, while frustrating, could not have contributed to the accidents.  None were willing to explore this issue.

It is well known that replies to NTSB Member letters are delegated to staff for preparation.  If I may be so bold, I’d like to nominate Bob Swaim or someone with equal objectivity and technical qualifications for the reply to this letter.  I worked with Bob on TWA 800 E3 issues.  Thomas Haueter can also be objective.  We worked together on the USAF CT-43A investigation in 1996.

 

Very Respectfully Yours,

Douglas J. Hughes, ISASI MO4415

Copies:

Chairman James E. Hall

Member John A. Hammerschmidt

Vice Chairman John J. Goglia

Member Carol J. Carmody

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