Hi Sylvia,

I just read your MH370 book and want to congratulate you on your approach and thoroughness. I am however a bit surprised at the omission of what seems to me (as a retired Boeing 747-400 captain) the simplest scenario, which is an electrical fire in the cockpit followed by a de-pressurisation.

I can readily envisage the following as a sequence of events.

Stage 1: Electrical fire starts generating smoke in the cockpit just as MH370 passes the FIR boundary. Smoke builds fast, and both pilots start donning oxygen masks. Electrical fires can be hard to detect initially and may or may not produce other symptoms – see the Swissair MD11 in 1998 for example.

I’ll preface the following with the caution that they are based on my experience of the B747-400 and B757, so may be inappropriate for this particular MH B777.

I don’t know how many commentators have actually put on an oxygen mask in a cockpit at night but it is not necessarily easy. Although the masks are designed to be put on quickly it is easy to screw up if not done quite deliberately. The harness that goes over the back of your head inflates as the mask is removed from its housing, but deflates when the right squeeze lever is released. If done in a hurry it is easy to end up with the mask out of its housing but un-inflated, so it needs to be held onto your face while you try to remember how to re-inflate it. That might take you out of the loop for doing anything else at all especially in a smoky environment.

In thick smoke not only will visibility rapidly decrease but your eyes will start to water. The pilots will then have only a short time to find and put on the smoke goggles, which it is unlikely that either of them will have practised. For the F/O, having only recently converted to the B777 this could be extremely challenging in a dark cockpit that is filling with smoke, undoubtedly causing a rapid adrenalin rush and extreme anxiety. The goggles may not seal properly over the mask and harness necessitating yet more wrestling and fumbling with equipment in a worsening situation.

With a mask and goggles on communication is seriously affected straight away: the mask microphone automatically becomes active. It will not be high quality voice and probably will amplify the breath noises significantly and facial expressions and other aspects of human communication are hindered. Depending on MH specific procedures, the pilots may or may not have been using intercom and headsets: these are frequently knocked off when putting the O2 mask and goggles on and may have to be retrieved, making communication even more problematic. The relative stiffness of the O2 mask connection also immediately restricts head movement compared to normal. These factors can often be observed even in the safe environment of a flight simulator where the real world signs of danger are absent and the situation has been anticipated.

So it is very easy to envisage that there could be confusion and a lack of coordination in the first few moments after smoke arrives, with every second of delay increasing the situation’s severity.

Stage 2 – the initial turn.

I can also envisage in this situation that one pilot (most likely the Captain) would register that an extremely critical situation had developed. Getting down on the ground as soon as possible would be a high priority resulting in a heading selection to start a turn-back, but not necessarily completing the action to a specific predetermined heading value. The thinking might well be “The aircraft will take time to turn, I’ll come back to it” – but then not having the ability to do so.

Stage 3 – loss of all communication.

I can also envisage that given the fact that as they had just signed off from one ATC unit but not yet established contact with the next, a radio call might not be the highest priority, especially if the intention was to return to Malaysian airspace. However setting the transponder to the emergency 7700 might be.

The B777 transponder control (at least in early models) is located on the aft aisle stand beside the F/O’s seat. Two rotary knobs select the values. The right hand of these knobs selects the second pair of digits, which would go to “00”. In a dark, smoke-filled cockpit, wearing goggles and an oxygen mask, it could be quite difficult to identify these knobs in a hurry, as the unit is not in either pilot’s primary field of view. Having made the first selection, in the developing crisis the pilot involved might well have been diverted to other aspects so not giving full attention to finishing the selection of the second set of digits – the “77” is the part that stick in the mind.

Most people turn knobs anticlockwise to reach zero. Immediately to the right of the second selector knob is the transponder mode selector. Turning this knob anticlockwise to its limit, instead of the right hand rotary knob, would select the transponder to Standby, rendering the transponder inactive.

So it is quite conceivable to me that in the circumstances I’ve described one pilot could inadvertently turn the transponder OFF while attempting to set the last digits of the 7700 emergency code, and that would not be noticed by the other pilot.

Stage 4 – depressurisation and loss of consciousness

If the postulated electrical fire had even some of the characteristics of that which occurred on the EgyptAir B777 Flight MS667 in July 2011, we can see the possibility of skin penetration leading to a rapid depressurisation. If the circumstances were almost identical (which is possible but not likely) the crew oxygen would also be depleted very fast. Skin penetration would not necessarily result in catastrophic structural failure, there are plenty of examples of aircraft continuing to fly with holes in them like the QANTAS B747 VH-OJK in July 2008.

If the pilots’ masks were not adequately in place because of the issues mentioned earlier, it might be that they would become incapacitated more rapidly than normally expected because of smoke effects as well.

Depressurisation at FL350 could conceivably result in oxygen starvation of the fire which started the problem, it becoming self-extinguished after the crew and passengers become unconscious. The autopilot remains engaged on the last selected heading until fuel starvation occurs and the aircraft crashes, as per Helios and others.

This seems to me to be the simplest scenario to produce the actual MH370 flight path. Pilots were simply overcome by abnormal events occurring, for which each element has ready precedents. What do you think?
Best regards
Steve Last

PS I have some illustrations of the B777 units but can’t see how to upload them

Egypt Air: http://www.civilaviation.gov.eg/accident/Reports/B777_SU-GBP_cockpit_fire_accident%20final%20Report%20responding%20to%20boeing%20comments%2019-09-2012a.pdf

QANTAS https://www.atsb.gov.au/media/2409291/ao2008053.pdf

Swissair MD11 1998 http://www.tsb.gc.ca/eng/rapports-reports/aviation/1998/a98h0003/a98h0003.pdf