The fact that MH370, an ultra-modern Boeing 777, ended radio contact and radar transponder transmission early in the flight from Kuala Lumpur to Beijing and flew a course right along the airspace boundary between Thailand and Malaysia before turning south, points to an intentional act by a pilot to try to avoid detection. In my article I pointed out that this shows the aircraft was under pilot control well after communications were lost because without an intentional act by the pilot the autopilot would have continued the track to Beijing.
I also relied on an unconfirmed report that Malaysian military radar revealed MH370 had climbed to 45,000 feet as it tracked across northern Malaysia, and that the only reason for doing this would be to incapacitate passengers and crew by hypoxia (lack of oxygen). Pilots, on the other hand, have masks with selectable pressure breathing capacity.
This week, Air Transport Safety Bureau spokesman Dan O’Malley maintained that the authority was standing by its preferred unconscious aircrew theory.
“The final stages of the ‘unresponsive crew/hypoxia’ event-type appeared to best fit the available evidence for the final period of MH370’s flight when it was heading in a generally southerly direction,” O’Malley said in a statement to The Australian.
There are two types of decompression events. The first is explosive decompression, which would have to be caused by some extraneous event such as a small bomb that causes a hole in the aircraft fuselage.
In cruise at 37,000 feet, the difference in pressure from having the cabin altitude at 6000 feet to outside pressure is 8.8 pounds per square inch (psi). Loss of all pressure would be very noticeable to the crew: ears pop, fog forms, there is noise.
Sitting alongside a pilot’s elbow is a quick-donning “octopus” mask that can be placed over one’s head with one hand to breathe immediately 100 per cent oxygen. This only takes seconds and is practised frequently in simulator recurrent training by airline pilots.
It is inconceivable that pilots from a world-class airline such as Malaysia Airlines would not, as their first immediate action, don their oxygen masks.
The time of useful consciousness at 37,000 feet is 20 to 40 seconds. This is plenty of time for the crew to react. The pilots’ next action is to initiate an emergency descent while selecting emergency on their transponder to alert air traffic control.
The second decompression event is creeping decompression and this would probably occur as the result of a technical fault in the aircraft’s pressurisation system. Bear in mind that cabin altitude and differential pressure are continuously displayed in green font on the pilots’ flight display.
Even if the pilots did not notice a slow rise in cabin altitude, the following would occur, courtesy of the engine-indicating and crew-alerting system. At a cabin altitude of 8500 feet an amber master caution light would flash continuously in front of each pilot (until cancelled by pilot action), plus there would be a loud chime as well as a “cabin altitude” warning.
This is to prompt the pilots to take action to sort out the problem by checklist action such as selecting manual control to give direct pneumatic control of the outflow valves to the pilots. The pilots may elect to carry out a rapid descent while troubleshooting.
If this did not fix the problem, then at 10,000 feet cabin altitude, the following occurs: there is a loud voice message — “cabin altitude” — plus three loud chimes, plus a red master warning light flashing in front of each pilot, as well as a red warning message “cabin altitude”.
This is to get pilots to initiate an emergency descent. If they do not, at 13,500 feet a cabin altitude limiter closes the outflow valves so the climb rate in cabin altitude can only be from fuselage leaking
The people from the ATSB should get some practice in an RAAF high-altitude pressure chamber, as I have done. (I once blacked out at 42,000 feet at night in a fighter jet due to a pressurisation problem and regained consciousness at 16,000 feet.) They should then stop basing their pilot incapacitation theories on 40-year-old movies
A spokesman for the ATSB has confirmed again that the bureau’s investigation is based on the theory of an explosive decompression leading to unconscious pilots due to hypoxia.
If this theory had been applied to Qantas, as an example, I am sure the Qantas chief pilot and plenty of line pilots would be offended at the suggestion they were not up to the task of handling such an event. This time-critical event is practised frequently and tested in simulator training as part of immediate action emergency drills, which are performed from memory.
At 35,000 feet the time of useful consciousness is 30 to 60 seconds but professional airline pilots are trained without hesitation — as their first action on recognising the explosive decompression — to put on their quick-donning masks with emergency 100 per cent oxygen. The managing pilot then initiates an emergency descent while the other pilot selects emergency on the transponder to alert traffic control and verifies that auto passenger masks drop.
Why would this have been any different with Malaysia Airlines? It beggars belief that its pilots would not react appropriately according to their training. An event that totally and immediately incapacitated the pilots would be so serious that it is very doubtful the aircraft could keep flying towards Beijing, let alone for another seven hours. The explosive decompression theory carries very little weight.
I have been criticised (rightly so — I am a pilot, not a journalist) for relying on newspaper reports without confirming the source of the information. An example of this is the supposed climb to 45,000 feet as the aircraft tracked across northern Malaysia. The data supposedly came from subsequent analysis of military radar.
A B777-200, after the 26-minute climb out of Kuala Lumpur for Beijing, would have approximately 40 tons of fuel left and with 239 people on board the optimum cruise altitude would be around 37,000 feet. This altitude would increase as weight decreased with the burning of fuel.
Virgin B737s generally cruise around Australia at 41,000 feet. The B777 would easily make 4000 feet above optimum (41,000) and at a stretch 43,000, but 45,000 would, with the thin air, not be possible as the wing loading would not permit it, even with the excess thrust of those big engines.
So why bother with a climb? If, as postulated, the captain, after donning his own mask, depressurised the aircraft, then the passengers would have only 10 minutes of chemically generated oxygen — assuming the captain had not disabled the auto drop function of the passenger oxygen system.
However, placed around the cabin are walk-around oxygen bottles with a mask that have a duration of more than one hour.
Were the aircraft to climb higher, this would render the walk-around oxygen bottles — if used by the cabin crew, or the co-pilot if he was locked out of the cockpit — ineffective in terms of preventing unconsciousness.
Above 35,000 feet, and especially above 40,000 feet, oxygen under pressure is required to prevent loss of consciousness as the pressure differential is insufficient for the lungs to get enough oxygen. Only pilots’ masks have this selectable pressure breathing capability. So this may be a reason for the climb.
After MH370’s 26-minute climb to cruising altitude, the cabin crew would be very busy with the service. A good captain, not wanting to interrupt the service, would request the co-pilot to go back to the galley and fetch a coffee or whatever. Since 9/11, airlines mandate the cockpit door is locked at all times and verification is required for entry to the cockpit.
The door unlock switchlight is on a console between the pilots’ seats. When a pilot wishes to leave the cockpit, he stands by the door while the other pilot briefly unlocks it, then re-locks the door after exit. Cockpit entry is therefore impossible for anyone if the pilot inside does not permit it.
Last week I cited a newspaper report that the flaperon found on Reunion Island was broken in a way that indicated low-speed impact with the water. The report attributed this information to John Cox, a renowned aviation safety consultant. It appears this information was from an unconfirmed source, not from Cox.
However, it remains the case that when retracted the flaperon is an integral part of the wing and would not be broken off separately unless it were lowered. The only way for that to occur would, in my opinion, be when an engine is torn off backwards when contacting the water, ripping the flaperon, which is immediately behind the engine, from its brackets — on the proviso that it is lowered.
The ATSB, after initially saying the damage to the flaperon was caused by a high-speed dive prior to crashing, changed its mind to say it supported the flame-out theory and an uncontrolled glide to a soft touchdown on water that explained the absence of debris.
Well, flying a heavy aircraft such as a B777 requires the pilot to start selecting flap so it can reduce speed to less than, say, 210 knots (400km/h). An aircraft without the flap lowered would be at such a speed that a soft impact would be impossible; it would be more like a crash, with broken parts and debris. We know it did not crash because there was no debris.
By Byron Bailey, a veteran commercial pilot with more than 45 years’ experience and 26,000 flying hours, is a former RAAF fighter pilot and trainer and was a senior captain with Emirates for 15 years, during which he flew the same model B777 as MH370.
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