Ok here's a pilot posting - I promise I've only just read this - and it kind of agrees with what I posit as the the most probablye scenario:
"not B777 rated , but 0ver 10K hours on B737's, I have been thinking about this for a while.
I cannot help but still think its a catastrophic loss of electrical power, similar to to uncapping the battery switch and turning it off.......poof...instant darkness, no back up stby power....just total silence.
The engines will continue to work, being totally capable of suction feed only, as long as no large thrust changes are made.
The hydraulics will still operate as the hydraulic solenoids are only capable of being turned-off with electrical power, and without electrical power they are designed to default to open.
but Autopilot, autoflight systems, avionics, radios ACARS etc and vitally important pressurization will all fail.
If the crew were rendered unconscious thru this, the aircraft could well start a series of climbs and descends because the thin air at 35000ft is not conducive to aerodynamic stable flight.....but once it gets into thicker air at about 20000ft, the aerodynamic forces will allow the aircraft to reach a relatively stable flight regime, especially if the aircraft was in a cruise trimmed position at 35000ft.
the climb to 45000ft also makes sense w.r.t electrical failure......MACH TRIM......the aircraft has a tendency to tuck nose down at high cruise mach numbers, so the electrical mach trimmer applies some "nose-up trim" and then balances this with applied forward deflection of the control column........the loss of electrical power and the aircraft would release its forward control column input, hence the climb, into even thinner air, followed by phugoid action, as it would drop off at the top, eventually it would settle into an "in-trim" cruise at a much lower more dense atmosphere
Why the turn, I cannot explain "
"not B777 rated , but 0ver 10K hours on B737's, I have been thinking about this for a while.
I cannot help but still think its a catastrophic loss of electrical power, similar to to uncapping the battery switch and turning it off.......poof...instant darkness, no back up stby power....just total silence.
The engines will continue to work, being totally capable of suction feed only, as long as no large thrust changes are made.
The hydraulics will still operate as the hydraulic solenoids are only capable of being turned-off with electrical power, and without electrical power they are designed to default to open.
but Autopilot, autoflight systems, avionics, radios ACARS etc and vitally important pressurization will all fail.
If the crew were rendered unconscious thru this, the aircraft could well start a series of climbs and descends because the thin air at 35000ft is not conducive to aerodynamic stable flight.....but once it gets into thicker air at about 20000ft, the aerodynamic forces will allow the aircraft to reach a relatively stable flight regime, especially if the aircraft was in a cruise trimmed position at 35000ft.
the climb to 45000ft also makes sense w.r.t electrical failure......MACH TRIM......the aircraft has a tendency to tuck nose down at high cruise mach numbers, so the electrical mach trimmer applies some "nose-up trim" and then balances this with applied forward deflection of the control column........the loss of electrical power and the aircraft would release its forward control column input, hence the climb, into even thinner air, followed by phugoid action, as it would drop off at the top, eventually it would settle into an "in-trim" cruise at a much lower more dense atmosphere
Why the turn, I cannot explain "
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