Aircraft Accidents and the Flight Data Recorder

During an NTSB Sunshine Hearing, a Board Member asked me my opinion of an air operator’s maintenance program.  I replied that, although I was quite versed in their program, I could not form an opinion because, as an investigator, it is not my place to judge.  I stick to the facts.  The Board Member, who never worked a night shift or turned a wrench, proceeded to condemn the air operator’s program.

You see, I leave the judgments to the ‘experts’.

I haven’t set my wake-up alarm in six years.  My son, the Army Medic, says I’m going to get sick; my wife of 34 years just says I’m Nuts.  However, how do I, with my eyes closed, ‘know’ it’s ten minutes before wake-up time every morning, no matter what time I go to sleep?  My belief it is some internal clock or sensor; it feeds information back to my brain that I’m totally unaware of.

Last week I spoke about the importance of the Cockpit Voice Recorder (CVR).  It’s sister data device, the Flight Data Recorder (FDR) is crucial to understanding what the aircraft did during an accident.  The ability to collect data, through a myriad of sensors, has increased exponentially in the digital age; where sensors connected to a flight control, e.g. Aileron, give direct readings on motion and position angle; this data is checked and rechecked through digital specialty computers up line.  Let me explain:

During the flight of a digital-age airliner’s flight – digital airliner numbers are in the high ninety percentile when compared to all airliners flying – a ‘Master’ computer is constantly checking the health and well-being of each of its ‘Slave’ component sensors, e.g. a flight control computer is interrogating each aileron, elevator, rudder, spoiler, etc. almost every minute during the flight by asking them, “How are you?”  You multiply that by every ‘master’ computer across every system, e.g. Air Conditioning, Pressurization, Hydraulics, etc. and it is safe to say, the airliner is very well-informed of its own health.

By the way, some of these system sensors are the reason flight attendants tell us to turn off cell phones and personal electronic devices; the aircraft’s electronics are very sensitive and are susceptible to outside interference.

But, back to the FDR: what role does an FDR play in the accident investigation?  Answer: An invaluable part.  Over the years, the necessary recording tracks assigned to sensors have multiplied exponentially from analog aircraft to digital; with additional tracks come the numerous sensors to record this previously unavailable data.  As I mentioned, the full myriad of sensors, all through the airliner, can locate with pinpoint accuracy an anomaly deserving of further investigation.

What does that mean, “deserving of further investigation?”  No data track is taken at face value.  For instance, an aileron was moved by either the pilot or autopilot in an ‘inconsistent’ manner at Cruise just before an accident.  There could be many reasons: from a faulty autopilot input to a response to winds aloft to the pilot bumping the yoke while getting up to use the bathroom; this could be crucial to an accident’s outcome, or coincidental; this data needs to be confirmed or discredited.

An FDR is a collection of data; it is defined by a timeline, e.g. in twenty second increments.  Each sensor track runs simultaneously with its fellow sensors; their tracks are divided into the timelines so we can ‘see’ what each sensor was doing at critical points in the lead-up to an accident.

But still something is missing, or better said, something else is necessary.  Last week I spoke about lining up the FDR and the CVR; only by doing so, could I understand that, e.g. the pilots were not expecting the emergency; that the flight was otherwise uneventful.  But by lining up the two recorders’ timelines, I could better understand how the emergency evolved; what the pilots knew in those final seconds and what totally astonished them.

So, is FDR data irrefutable?  I would never say that.  Anything can be intentionally or unintentionally corrupted; the adage that, ‘if you torture the data long enough it will confess [to anything]’ is very accurate; in politics, we have seen this many times over the last few decades.  In my blog last week, the data was interpreted with an eye on preconceived notions; this resulted in a battle between me and other investigators.  But if analyzed correctly, the FDR and CVR data are major pieces in an investigatory jigsaw puzzle.

So, wouldn’t cockpit video be even more helpful?  Probably not.  It is my opinion that video is the quintessential bad idea of bad ideas.  I say this with complete conviction, partially because of my experience, but also because of common sense.

For one, we give video too much credit; we rarely contradict what is before our eyes.  However, with different size cockpits and various placements of pilot and check-rider seats, where do you put a camera to capture all that goes on?  On a flight deck, that can be flying away from the sun and within five minutes face the sun, how do you adjust for lighting and glare?  It would make the evidence more confusing.

For two, the cons for videoing professionals doing their jobs outweigh the pros.  Standing over ones shoulder in a crisis is counterproductive; doubt, resulting in pilots second-guessing their own decisions.  The results?  Delays in critical thinking and responses the flight crews may perform.

I qualify that by pointing to recent video escapades.  How have we tied our police forces’ hands these days?  They are understandably hesitant to make life-or-death decisions due to some person(s) taking video.  These recordings conveniently eliminate the events prior to and immediately following the incident, the Paul Harvey ‘Rest of the Story’.  The ability for anyone with a camera to confound the events can turn trained experts like police and emergency responders (and, if cockpit videos are passed, pilots) from decision-making proactive professionals to second-guessing reactive people.  I can’t think of anything more dangerous.

The United Airlines incident, where the passenger was removed from a flight, has made the rounds this week.  I refuse to chime in; I don’t doubt my eyes, but a snippet of i-phone video is not enough for me to make a determination of what preceded and what followed.  The video is like a partial quote, conveniently removing the important words to forward a particular narrative.  I refuse to judge what happened; I continue to stick to the facts.

I’ll, instead, leave the judging to the experts.

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