The Swiss Cheese Factor

Why Malaysia Airlines 370 remains so profoundly mysterious, and why a better black box wouldn’t help

March 14, 2014
March 14, 2014
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Track of Malaysia Air 370 on March 7.(FlightAware)

Here is the heart of the mystery over what has happened to Malaysia Airlines flight 370:

  • If the airplane did keep on flying, presumably there would be evidence of that fact—at a minimum through “primary radar returns,” blips on civilian or military radar screens showing that something was in the air even if the plane’s transponder was not sending back specific identifying info.
  • If the airplane did not keep on flying, presumably there would be evidence of that—through wreckage on the ground, oil slicks or debris in the sea, satellite detection of a flash or explosion at the relevant time.

As of now, six days later, there is no clear evidence of either type. Or other evidence to suggest difficulties with the weather (in contrast to Air France 447—and I’ll have more on this soon), suspicious actions by passengers or attackers, problems with the flight crew, a pattern of failure with this kind of airframe, or any of the other usual components of the “accident chain” in aviation disasters. As I mentioned earlier, airline travel is now so amazingly safe that when something does go wrong, the cause usually turns out be some previously unforeseen triple-whammy combination of bad-luck factors. Air-safety experts refer to this as the “Swiss cheese” factor: the odd cases in which the holes in different slices of Swiss cheese happen to line up exactly, letting the improbable occur.

But so far MAS 370 is in a category of its own, in the shortage of useful data and the mismatch of what is known with most imagined scenarios. This is a source of additional heartache for affected families, anxiety for some in the traveling public, and embarrassment for the Malaysian officials clumsily running the search. (As mentioned, I am a fan of Malaysia-the-country and of Malaysia Airlines, but Malaysian safety officials are looking bad.) Yet it is the frustrating reality. The closest comparison would be the crash of TWA flight 800 18 years ago. The absence of data is itself a surprising data point.


Now, about one common pundit claim: If only we had better “black boxes,” and more real-time streaming of black-box data, we’d be spared mysteries of this sort. Michael Planey, a Washington-area consultant who has worked for several airlines and did air-safety investigations for the Air Force, writes in to explain why this is a false hope.

I’m quoting his message in full detail, since in cases like this the details matter. If you don’t want to deal with all the specifics, his main point is: the disappearance of this airplane remains profoundly mysterious, and would probably remain so even if one much-discussed “remedy” had been in place. I turn the floor over to Mr. Planey:

Would realtime streaming of black box data end the mystery of what happened to MH370? Probably not.  Here’s why.

As the search for Malaysia Airlines flight 370 continues in earnest, many have called for the implementation of realtime streaming of black-box data.  It is an understandable reaction to an inexplicable event:  that a modern airliner could simply vanish without a trace.  The thinking is that real-time black-box data would make it possible to locate the aircraft more quickly; to understand what had happened to the aircraft causing it to lose contact with air traffic control; to perhaps prevent an aircraft safety incident through monitoring of aircraft systems and highlighting suspect or anomalous data.  But is that really the case with this aircraft and this flight?  Unfortunately, I suspect not.

The last loss of a commercial airliner in trans-oceanic flight was Air France Flight 447 on June 1, 2009.  In that case, some system failure reports and warnings were transmitted via ACARS [JF note: a data transmission system linking in-flight airplanes with ground stations] in the last moments before the aircraft crashed into the Atlantic.  This data was useful in the preliminary understanding of the event, but it was not enough data to paint the complete picture of the complex system failures and flight crew actions that led to the crash, nor prevent it from happening.

In that case, the data transmission was of no particular use in locating the debris field.  Rather, traditional air traffic control and radar data was used to pinpoint the last known location of Flight 447 and the search began at that point.  The aircraft wreckage was located by the next day in the expected area.  In the current case of MH 370, the same type of location data is available, but the search has been fruitless.  This opens the up possibilities of the aircraft’s fate to scenarios where data-streaming would again be ineffective.

Given that the Boeing 777-200 aircraft on this flight had been recently inspected and operated without incident over the prior ten days, there are no red flags leading to a likely cause of the disappearance.  Even though this aircraft was equipped with an ACARS system like the Air France flight, no relevant data transmissions were made.  This reasonably points to a thoroughly unforeseen, catastrophic event (such as TWA Flight 800) or perhaps a deliberate action such as hijacking, terrorist action or even flight crew suicide.

In the case of the immediate, catastrophic event, data streaming would likely cease at the moment of the event.  Either a complete loss of electrical power would disrupt the data stream or a mechanical break in the aircraft systems would prevent data transmission.  Further, if an aircraft was in an out-of-control attitude such as a steep dive, a spin or a hard roll, maintaining a direct link with a satellite would be nearly impossible, thus again breaking the data stream and rendering the system incapable.

If the demise of MH370 is due to a deliberate action, realtime data-streaming is again unlikely to yield definitive answers.  If hijackers were sophisticated enough to completely cut-off all communications (radios, ACARS, transponder, ADS-B) then it would stand to reason that the data link would be cut off in the same manner.  Further, the detonation of a bomb would not show a prior indication of the event in the flight data-stream.  Perhaps, the very slight chance of aircraft depressurization or loss of fuel volume would be detected at the moment, but it is unlikely that such a signal could be successfully transmitted before the communications system was rendered useless.

It is important to note that the “black-box” is actually a pair of boxes.  The Flight Data Recorder secures information from a host of flight systems and the flight management computer.  The Cockpit Voice Recorder captures the last 30 to 60 minutes of dialogue in the cockpit and adds significant context to the FDR data.  In the investigation of AF447, the CVR was critical to understanding why the flight crew took the actions they did, even as the data could show what those actions were.  Capture of both information streams would be necessary for a full picture of what was happening at the critical moment.

If days of intensive air and sea search efforts have yielded no clues, it is hard to believe that the aircraft and its crew were capable of providing any more useful information at the time the aircraft disappeared.

This originally appeared on The Atlantic. Also on our sister site:

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