A Pilot's Thoughts on Malaysia Flight 370

So it's been more than a week since Malaysia Airlines flight 370 went missing.  The entire world is speculating on what happened to the airplane, so I'll go ahead and add my scenario.   It's not as exotic as the current hijacking scenarios, but I think it's a lot more realistic.

The aircraft disappeared at FL350 (35,000') while in cruise flight as it was being handed off from one air traffic control agancy to another.  The radio communications were normal - there was no distress call and no terrorists accidentally transmitting over the radio thinking they were talking on the PA (as happened on 9/11).  Therefore, whatever happened aboard the aircraft happened quickly.  If someone had been trying to break into the cockpit, you can bet there would've been a transmission over the radio.  The possibility that one or both of the pilots simply stopped transmitting over the radio, turned off the transponder, disabled ACARS and flew the airplane to an unknown destination - or just crashed it - is very unlikely.  As of the most recent news I've seen, neither pilot had any sort of motive to do something like that. 

The event aboard the aircraft happened quickly, and I believe it was a pressurization issue.  As pilots we are trained to don our oxygen masks, establish communication with the other pilot, and perform an emergency descent to 10,000' if we lose pressurization.  Unfortunately, there have been cases where the pressurization warning has gone off and the crew believed it was a different warning, so they began troubleshooting before donning their oxygen masks and simply passed out before they figured out what was really happening.  On the 737 (I can't speak for the 777) the cabin altitude warning horn is the EXACT same as the takeoff configuration warning (the horn that sounds if we don't have the flaps out for takeoff).  You can see how that would be confusing in flight and could lead to the crew's incapacitation  as it did on Helios 552.  

I believe it's most likely that the crew of Malaysia 370 had a rapid or explosive depressurization.  Following the event the pilots became hypoxic while attempting to place the aircraft on a course toward land, keeping lateral navigation engaged with the autopilot.  The vertical navigation was probably controlled by "Level Change" as we would do in an emergency descent, which explains why the plane descened and climbed indiscriminantly.  In their state of reduced mental and physical capacity they mistakenly switched off the transponder, and in an attempt to establish communication they moved the third VHF radio from "Data" to a communication frequency, thus disabling ACARS.  

My theory has been hinted at, as in this article, but I'll get even more specific in my speculation.  The emergency oxygen supply for the pilots is contained in cylinders similar to scuba tanks.  These tanks have been known to fail (read explode) as happened with this Qantas 747.  Even if the pilots had donned their masks, the oxygen supply was nonexistent, and their incapacitation was assured.  IF that's the case in this event, the pilots did a remarkable job attempting to begin a descent and turn back toward home before oxygen starvation took their lives.

Regardless of what we find out, I hope the aircraft will soon be discovered.  The families deserve to know what happened to their loved ones, and those of us who live and breathe aviation will probably learn something as well.  I've never been more anxious for answers. 

I welcome your comments and questions!

  1. CXA872

    #1 by CXA872 - March 17, 2014 at 2:24 PM

    I've thought the same thing and I've seen the test pilots go through when you lose oxygen. It's safe to say you can have a hard time knowing left from right when you're oxygen deprived.

    If this is the case how can we explain both the ACARS and transponder being turned off? No emergency procedures ever include turning these off.

    Also, what's your take on the emergency crash beacons not going off?
  2. kris

    #2 by kris - March 17, 2014 at 2:31 PM

    ACARS (at least on the 737 I fly) operates through the data mode of the radios (HF, VHF or Satcom). If the radio that ACARS uses is simply switched to a non-data mode ACARS is inop. It's possible that an explosion of some sort could've disabled VHF 1 and 2 - I'm not sure. As far as the ELTs I'm sure they ARE going off wherever they are. Depending on the type of ELT it may not be able to be received unless you're in fairly close proximity. It's a big world out there!
  3. Marcin

    #3 by Marcin - March 17, 2014 at 2:34 PM

    I seem to recall reading something that specifically says the depressurisation warning on a 777 is different than anything else, unlike the 737, but I'm not 100% sure.

    How difficult is it to turn the transponder off? Is it conceivable that they could've accidentally done that while oxygen deprived and trying to switch the transponder to an emergency code? (that's a thing, right?)

    But yes, as fascinating as some of these theories are you'd have to assume Occams Razor applies and the simplest explanation is the most likely!
  4. kris

    #4 by kris - March 17, 2014 at 2:51 PM


    Yeah, I'm not sue about the 777 cabin altitude warning either. Probably *is* different. But it would be really disorienting and confusing if you had a rapid or explosive decompression.

    It's just a switch. You could bump it off by accident. Not that I have. And yes - that it was turned off when going for the emergency squawk is very likely. I hadn't actually thought of that. Makes perfect sense.
  5. SK

    #5 by SK - March 17, 2014 at 2:57 PM

    If it was on the ground one of the passengers would have used their mobile, unless it's in such a truly remote location. Also I'm sure somebody would notice a 777 on a runway where it shouldn't be. Your theory makes complete sense.
  6. Joe

    #6 by Joe - March 17, 2014 at 6:54 PM

    Interesting, but what do you make of this:


    After comm was switched off, the plane apparently charts a course over some very specific waypoints; points that would have had to be manually entered into the autopilot by an expert. In the event of an explosive decompression compromising the crew, it does not follow that the plane would chart such a flight path. That course would have to have been predetermined, indicating foul play.

  7. Sumner Nelson

    #7 by Sumner Nelson - March 17, 2014 at 10:16 PM

    Possibly additional parts of the story include:
    The captain's wife and three children moved out of the house the day before.
    The captain attended the court proceeding of his pro-democracy political party's leader that day, when that leader was sent back to jail on trumped up charges of sodomy.
    The aircraft went up to FL450, (to dump the pressure vessel?) marginally above aircraft limits, then back down to FL29.5.
    The aircraft then tracked a set of waypoints west, northwest bound. Which wouldn't have been pre-programmed.

    Just saying...
  8. kris

    #8 by kris - March 17, 2014 at 10:46 PM

    Joe - one of the first priorities of the crew would've been navigating toward an airport. "Some very specific waypoints" sounds more important than it probably is, maybe even incriminating to a non-pilot. Every waypoint is specific. We have airways - highways in the sky - which are defined by waypoints. If the crew was scrambling to punch a route into the flight management computer in order to aim toward land, they might have simply selected a pre-programmed route and the plane would've begun a lateral course in that direction. In the confusion and disorientation of an event like that having at least a good initial heading is important.
  9. kris

    #9 by kris - March 17, 2014 at 11:26 PM

    Sumner - My theory was based on the information I had at the time. I hadn't heard the items you mentioned. However, it is all speculation, isn't it? Not to entirely dismiss the implications of your points, but I think the press likes drama more than fact on most days. The picture that paints is ugly and I despise it.

    I don't remember the ERJ too much anymore, but the Boeing aircraft have "canned" routes plugged in that we can call up in just a couple keystrokes, so programming isn't even necessary. If you're cold, disoriented and possibly hypoxic I doubt you're going to be able to perform a lot of really coherent actions. If they were able to at least get the jet headed in a good direction that would be a good start in such a situation. I'll always give the pilots the benefit of the doubt until it's shown otherwise. As a professional jet pilot I hope you will too.
  10. matt

    #10 by matt - March 18, 2014 at 5:07 AM

    Does the depressurization suck the air from your lungs?

    When I used to free dive I could very comfortable do a 5 minute breath hold if sitting still on a bed etc.
    however if under 20 metres of water due to the compressed nature of that air plus the energy from swimming etc I couldn't last anywhere near as long.
    So my question, if a pilot didn't panic could he simply hold his breath for a couple of minutes?
  11. kris

    #11 by kris - March 18, 2014 at 10:40 AM

    Matt - At altitude the air in your lungs is at a higher pressure than the air outside. If the plane depressurized the relatively high pressure air in your lungs would seek the lower pressure outside. In other words, the air in your lungs would expand and try to escape rapidly. This is opposite of free diving or scuba diving. On a standard day at sea level the air pressure is 14.7psi (one atmosphere). Every 33' you dive under water is an additional atmosphere (14.7psi), so the pressure around your lungs at depth is greater than the air pressure inside your lungs. So to answer your question, no, you can't hold your breath.
  12. Debbie

    #12 by Debbie - March 18, 2014 at 11:53 AM

    My thoughts: http://sulia.com/foxie/f/62b2967a-1449-4c23-8201-e67f3d21aaa8/ I don't have a theory because I don't believe we've been told enough. I don't think it was the pilot though. We only have a Sorta Motive (his relative Anwar Ibrahim) but that's just not enough for me......
  13. Debbie

    #13 by Debbie - March 18, 2014 at 11:57 AM

    ps Every pilot I've talked to agrees that it had to be mechanical. I also think it's right where they KINDA searched, a bit to the right of where it was last on actual radar. Stopping the search there is a mistake. But it might be a deliberate mistake..... wouldn't fit their Rogue Terrorist PKR Captain theory...
  14. Bogissa

    #14 by Bogissa - March 18, 2014 at 8:56 PM

    I don't believe this theory to be correct I believe it to be similar to the AF447 accident where the pilots stalled the aircraft but could not recover in time.
  15. Tom Rees

    #15 by Tom Rees - March 19, 2014 at 1:42 AM

    How do you explain the final position of the aircraft (as revealed by satellite pings? Wouldn't it have had to change course again after overflying the Maldives?
  16. Kris

    #16 by Kris - March 19, 2014 at 2:00 AM

    Tom - not necessarily. Keep in mind we still *don't* know where it is (I just landed in Hawaii so maybe there was news I haven't seen yet). If the jet was flying in "heading select" it would've just kept on flying a magnetic heading in a straight line until it crashed. If it was in LNAV it would've followed the GPS course from the flight management computer. AND if there was a route discontinuity in the FMC it would've just flown wings level after its last waypoint before the route discontinuity.
  17. Tom Rees

    #17 by Tom Rees - March 19, 2014 at 3:08 AM

    Only that if the plane kept heading West (or even turned northwest towards the Andemans), then the final location wouldn't match with the northern or southern 'arcs' http://news.bbcimg.co.uk/media/images/73636000/gif/_73636672_malaysian_airliner_search_624map.gif Maybe the calculation of that arc is wrong though - that

    Only news this morning is the US investigators say the route was programmed in 12 minutes before final radio transmission. They don't say how they know that.
  18. Craigaroo

    #18 by Craigaroo - March 22, 2014 at 7:33 PM

    Very good. Interesting bit to bring up how ACARS can be disrupted by simply changing VHF radio settings. As a non-pilot, I'm curious about the use of "Level Change" in an emergency descent. Does this mean the plane's autopilot system brings the plane lower? There are reports that the plane flew as low as 5000 ft as it recrossed the Malaysian peninsula -- at this altitude, cabin pressure should be sufficient for needed oxygen levels unless the pilots were already unconscious at this time, but then what would explain the plane's regaining altitude by the time military radar last made contact with it in the Straits of Malacca?
  19. Simon Gunson

    #19 by Simon Gunson - March 23, 2014 at 4:33 PM

    I agree with this article's suggestion that the aircraft might have depressurised whilst crew were fighting to overcome another different problem (ie electrical failure) At 35,000ft pilot incapacitation can ensue within 30-60 seconds. Egyptair Boeing 777-200 Flight 667 suffered an avionics bay fire in 2011 which spread under the co-pilot's seat as the aircraft was awaiting pushback. Pilot oxygen lines fed the flames. At the appropriate time for MH370's disappearance Oil Rig worker Mike McKay saw an aircraft high in the sky, west of him over the Mekong Delta on fire for 10-15 seconds before the flames went out. To me it seems plausible to have an electrical fire fed by pilot oxygen burn through the aircraft's skin to depressurise the entire aircraft.
  20. Simon Gunson

    #20 by Simon Gunson - March 23, 2014 at 4:38 PM

    Kris I am a former scuba diver, private pilot and loadmaster. I saw an interesting comment about the effect on lungs and I do know from SCUBA diving that rapid ascent with bottled air in the lungs can cause air embolism, where air bubbles travel to the brain and effectively your lungs are over-pressurised. Is this a known factor?
  21. Simon Gunson

    #21 by Simon Gunson - March 23, 2014 at 6:20 PM

    Kris one last point please, if we assume there was an electrical failure, followed by fire, leading to rapid decompression, then please could you comment on possible ADIRU failure and whether after the flight management computer and autopilot crashed, then to what extent would they spontaneously re-boot?

    Why I ask is that let us assume the pilots were permanently incapacitated by decompression, and electrical failures whilst the aircraft was on autopilot, if there was failure of the ADIRU followed by an automatic re-boot would the autopilot disconnect and if so would the autopilot come back online or stay disconnected?

    Was there any similar auto-throttle re-booting behaviour in the Asiana B777 crash?

    I am trying to grasp whether MH370 could have flown on by autopilot?
    I wonder if the autopilot disconnected with incapacitated pilots would the autopilot reboot with the ADIRU reboot, or stay disconnected?
    Surely an electrical failure would disconnect the autopilot?

    What I am trying to get at is if the crew and occupants expired without the electrical failure being properly resolved and kept recurring, could the electrical fault continue shorting systems whilst on autopilot leading to a succession of turns, dives and climbs, over 7.5hrs with persistent drop outs and re-boots?

    Otherwise i can't figure out why it wouldn't just fly straight for 7.5hrs in one direction?
    The alternative is an aircraft flying with no human intervention or autopilot, so how viable is that?
  22. kris

    #22 by kris - March 26, 2014 at 1:59 AM

    Simon - Great questions and I'll do my best to answer them, but the truth, as we know, probably eludes all of us. Sorry for replying so late, but it's been a really long few days for me ;)

    With regard to pressurization and the effect on your lungs, hypoxia end embolism are precisely the problem. Generally these events are classified by the rate at which the cabin depressurizes. I'm not sure what the specific criteria are, if there even are any, but typically I would consider three events: a pressurization failure (slow leak or failure to pressurize at all), a rapid decompression (a pressurized aircraft loses its pressurization in a short period of time, probably a matter of seconds or tens of seconds), and an explosive decompression (losing pressurization almost instantly or within a matter of seconds). The faster the aircraft depressurizes, the greater the risk of an embolism, although I think I'd say that would be the least of my concerns because it's the least likely scenario. Loss of useful consciousness (hypoxia) is the most likely scenario because it can happen in seconds. It is affected by the person's health, if they smoke, the altitude at which the depressurization occurs, etc. The most important step is to get the oxygen mask on and keep breathing pressurized air. Yes, our masks are different than what the passengers have, and the masks we have are the quick-donning type. We don't have to wait for them to fall from overhead. After masks are secured to our faces, the next step would be to descend to an altitude where we could all breathe - 10,000' is generally the target. Here's what the masks look like for reference: http://bit.ly/QePwwk

    I believe that the pilots probably began the process of a rapid decompression/emergency descent, but the succumbed before they were able to get very far into it. What most people don't understand (although you do because you're a private pilot) is the notion of aircraft stability. If you let go of the controls the plane doesn't just plummet to the earth below. It maintains its current airspeed and direction until acted upon by another force without any pilot or autopilot input.

    If the aircraft was in LVL CHG (pitching for airspeed) that would definitely explain the altitude fluctuations, and it certainly could've done that for hours. I read that the plane climbed to 45,000'. Not sure how they came to that conclusion, but that had to have led to a stall. A stall would then cause the plane to roll left. It would take thousands of feet (probably even tens of thousands, depending on the thrust setting) for the aircraft to recover and begin to climb again. The plane would continue to oscillate altitudes endlessly, but the track across the ground could vary. It would've done its best to maintain heading in HDG SEL or a GPS course if LNAV was engaged with the autopilot, but I think there might not have been any lateral guidance at all - just the 777's inherent lateral stability with autopilot disengaged.

    Here's the setup:

    * BOOM! - Rapid or explosive depressurization
    * Cockpit and cabin fill with moisture vapor as the warm air inside the plane (+20 degrees C) meets the cold air from outside (-50 degrees C)
    * Dirt and other particulate fly throughout the plane making it impossible for crew to see
    * The temperature inside the plane plummets quickly to well below freezing
    * After several seconds pilots don oxygen masks, but don't switch to "Emergency" - it takes some practice and effort to make that happen, and we don't do it every day.
    * Recognizing that they need to descend they put the altitude mode in LVL CHG and manually pull the throttles to idle to begin a descent, but in the confusion they forget to disengage the auto throttles. This leads to an initial descent, but the auto throttles bring the power back to max causing the jet to climb (the initial oscillation).
    * In an attempt to notify ATC of the emergency there's an attempt to squawk emergency in the transponder, but instead the transponder is accidentally switched off. This marks the beginning of the loss of useful consciousness.
    * The crew becomes hypoxic and ultimately succumbs.
    * The wings stall at high altitude with max power
    * The jet rolls left and dives to regain airspeed
    * It overshoots its target airspeed and begins to climb again
    * A series of altitude oscillations, stalls and course changes continue until the 777 runs out of fuel and crashes

    Regarding the scenario you suggest - either an electrical failure will be contained (circuit breaker pops) or a fire will ensue. If a breaker pops that's not too big of a deal because at that point the affected systems are isolated. If a fire breaks out, then the crew *has* to extinguish it. If they don't the aircraft will burn until it's destroyed. So the notion of an "electrical failure being properly resolved and ... recurring" doesn't make much sense to me. That's why I've never really believed that this was a fire, only a *single* failure - decompression.

    The ADIRUs are connected to just about everything including the first class coffee pots (jk) but are not going to reboot and engage the autopilot. I don't believe there was *anything* wrong with the Asiana 777 that was lost in SFO.
  23. kris

    #23 by kris - March 26, 2014 at 2:31 AM

    Here's the incident that Simon mentioned with the Egypt Air 777. Hmm...
  24. Simon Gunson

    #24 by Simon Gunson - March 26, 2014 at 10:55 AM

    Hi Chris just a follow up that some of my questions or comments seem redundant now since the release of UK AAIB analysis of INMARSAT satellite data, revealing a turn west to head south, also that it flew steadily at altitudes "above 30,000ft." The Malaysians made fools of us all with their thriller novel narrative of aircraft climbing then descending and zig-zagging about the Straits of Malacca. I was trying to understand how an autopilot could do this and of course now we get a different report that it stayed on autopilot and cruised steadily south. Sorry to tax your brains but great replies too. I enjoyed your sharp logic.
  25. Cyndi L. Hendry

    #25 by Cyndi L. Hendry - April 27, 2014 at 8:18 PM

    Thank you Kris for your thoughts on the MH370 possible scenarios. I am one of thousands of crowd-sourcing keyboard warrior volunteers who have reviewed maps provided by Tomnod.com so that we may help look for MH370. On 3/18/14 I found numerous pieces of debris. I have since reviewed maps from 3/9 & 3/11, both show debris as well. All the maps are from the Gulf of Thailand, and the debris is in the left turn zone. And is located in the 40 degree zone that Inmarsat has touted that that is where debris/plane will be found. Only they are looking in the Indian Ocean and MH370 is STILL MISSING. I have documented most of the chunkier pieces in my website that I have provided. I have utilized a scale overlay of a T7-200 to some of the debris and they match exactly with the overlay. Visit my site to view all that I have gathered to date regarding MH370. Thanks again for your thoughts. Unfortunately, I do believe that there was an explosion. The two wing images show black pitted markings perpendicular to the fuselage and directional from the cockpit area. https://plus.google.com/photos/108116867684876075087/albums/6006569666803951553?banner=pwa
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