The likely B-777 scenarios are narrowing down to just one
When the Malaysia Airlines Boeing 777 vanished almost a
month ago speculation was rife about its fate: Suicide terrorism, criminal acts
by passengers or crew, hostage taking, catastrophic structural failure
(something that has never happened to the 777 in its 20 year history) were all
on the table.
Although widely criticized as incompetent and dishonest,
the authorities were wise to play their cards slowly while some form of
criminality was considered highly likely. To do otherwise may have played right
into the hands of those responsible. But the likelihood of criminal
interference, or criminal actions by the pilots, are now receding.
Much news media mileage has been made of the captain’s
flight simulator, but lots of pilots have their own simulator and many former
pilots regularly ‘fly’ on a simulator. In my own case I’ve spent many hours on
various Boeings including the 777. It’s not uncommon to indulge in flight activities
that would be most unwise in the real aircraft. For example I sometimes
simulate returning to the airport after all power is suddenly lost during climb
out at 15,000 to 20,000 feet. Large jets are capable of gliding much better
than many people would imagine.
Simulators, airline and private, have have done a lot to
make flying safer. They keep pilots ahead of the game, and it’s my belief that
the Malaysian pilots were right up with the game until fate took a hand. Every
pilot worthy of the title will always fly with an instant action plan in mind
to cover every possible emergency.
In the flight plan there may be only one alternate
airport for diversion in the event that the destination cannot be used. But
every minute of the flight the crew will always know the location of the
nearest suitable landing place, and in a life and death emergency turning toward
that airport will be the first priority.
We know now that shortly after the last communication the
aircraft suddenly turned from a northerly heading to a south westerly heading on
a course that would take it into the southern
Indian Ocean. But that heading
also pointed the aircraft to a 13,000 foot runway in Malaysia that was closer
than the departure airport.
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The next actions should have been to start the descent and
transmit a distress call. The rule is Aviate Navigate and Communicate, in that
order. The autopilot would have been used to turn the aircraft onto the new
heading and the altitude bug may have been turned off while the pilots selected
a new flight level and rate of descent. But programming the autopilot may have
been interrupted when the pilots were suddenly incapacitated.
The likely culprit must be decompression, poisonous fumes of some kind;
a smoldering tire, or fumes from the consignment of troublesome batteries that
were in the cargo hold. The fumes from those batteries can kill within 10
seconds.
So we have a situation where the aircraft is trimmed for
the turn (slightly nose up) and is being flown partly manually and partly by
autopilot. If the pilots are unconscious at the completion of the turn the
aircraft will climb. This may explain why it climbed 10,000 feet above its
assigned altitude. At 45,000 feet the 777 would be struggling to fly and left
to its own devices the nose would drop quite steeply. As it gained airspeed
again it would level off and start another climb. This may explain the sighting of a jet airliner flying
low and fast over the Malaysian Peninsula around the time that MH 370 would
have been crossing.
The process may have taken several oscillations before normal
flight resumed on the new selected heading, possibly with the altitude
increasing slowly as the fuel load burned off. It all depends on the actual
settings for the autopilot; heading we can be fairly certain of, but airspeed,
altitude and power settings will only ultimately be revealed when the black box
is recovered. It is possible that the airspeed at the top of the climb may have been very close to the minimum airspeed to remain airborne, or close to the point of stall.
When the aircraft ran out of fuel it is likely that one
engine failed before the other and the asymmetric thrust at the low air speed would probably
disengage the autopilot completely. The remaining engine would wind
the aircraft into a graveyard spiral with the airspeed then increasing very rapidly.
If the last engine failed a few seconds after the first
it would make little difference. Once in the spiral without a conscious pilot at the
controls the aircraft would in all probability disintegrate before hitting the sea.
In aviation anything is possible once. In most other
fields of endeavor the same mistakes can happen over and over again, but
aviation is different. Aviation learns from its mistakes. That is why flying is
safe.
But that is no consolation for the victims and their
loved ones. However, if my scenario is the correct one, then the suffering was probably
very brief.
UPDATE
30th July 2015
Wreckage, possibly from MH370, has been found washed up on Reunion Island in the western Indian Ocean, several thousand kilometres from the search area south west of Perth in Western Australia.
So, was the search being conducted in the wrong place? Possibly not. A study of the ocean currents tends to confirm that wreckage from the search area could indeed be carried on a circuitous route north, west and then south to the area of the find.
UPDATE
30th July 2015
Wreckage, possibly from MH370, has been found washed up on Reunion Island in the western Indian Ocean, several thousand kilometres from the search area south west of Perth in Western Australia.
So, was the search being conducted in the wrong place? Possibly not. A study of the ocean currents tends to confirm that wreckage from the search area could indeed be carried on a circuitous route north, west and then south to the area of the find.
Indian Ocean currents/Wikipedia
If the wreckage found is confirmed as coming from MH370 then is can be expected that other wreckage may be scattered over a wide area of the ocean, the drift depending on shape and weight of individual items. For the flaperon to detach from the aircraft, the way it must have, indicates that there may be dozens, perhaps hundreds, of small pieces of wreckage, indicating a possible break-up in the air, possibly in a graveyard spiral after fuel exhaustion.
This must be regarded as the most significant clue so far in the search for the missing airliner, and those on board.