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[05omegav6]

SR111 was over land at the initial PanPan call, but was diverted back out to sea in order to dump fuel (and lose altitude)...
Had ATC actually been informed of the fire, rather than the ambiguous 'smoke in the cockpit', things might have played out differently... as it was no one could have suspected fire retardent insulation to be so combustible 
The net result would have likely been the same though

However, in the case of MH370, they had enough time to climb to 45,000, then dive to 23,000, change course twice and fly two hundred miles without so much as an 'Oh cock!'...

That I don't buy

[Entwood]

SR111 was over land at the initial PanPan call, but was diverted back out to sea in order to dump fuel (and lose altitude)...
Had ATC actually been informed of the fire, rather than the ambiguous 'smoke in the cockpit', things might have played out differently... as it was no one could have suspected fire retardent insulation to be so combustible 
The net result would have likely been the same though

However, in the case of MH370, they had enough time to climb to 45,000, then dive to 23,000, change course twice and fly two hundred miles without so much as an 'Oh cock!'...

That I don't buy

yup .. those actions make no sense... from an emergency handling POV .. but if you wanted to incapacitate your passengers, and you had a separate, independent, oxygen supply you KNEW you could rely on for 20 minutes or so .. then after about 12 minutes all your passengers are unconscious (or worse)  ... the only "working" solution is a deliberate act in order to "hijack" (?) the aircraft .. the big questions are  ..

Who - crew or others ??

Where - ??

Why - ??

[05omegav6]

Who... crew is a given, especially in view of the discovery of simulators in both of their homes. Either for cash or cause

Where... can only guess, based on the Why.

Why... No warning/Big Announcement/note/crash site... only leaves sinister and disturbing as options Neither bodes well.

Had it been some sort of stupid prank, then you could expect postcards from various places... remember that gnome a few years back?

Only a matter of time before it turns up somewhere, and I guarantee it won't be in the Indian Ocean

Only a matter of time before all Transatlantic flights are forced to transit through Terciera Lajes AFB in the Azores.
Anything outside not routed through there would be liable to be shot down. Another possibility could be enforced stop overs of 24 hours for a transiting passengers, with secure airport accomodation and enhanced security screening between flights

[Kevin Wood]

Could a 777 really climb to 45k that early on in the cruise, or at all?

More likely an artifact of the report being from primary RADAR, right at the extent of its' range, IMHO. Or it climbed, stalled, and recovered at 23k.

[05omegav6]

What determines the operational ceiling? Is it the engines, the airframe or the passengers?

Guess physically it would be the engines

[Kevin Wood]

What determines the operational ceiling? Is it the engines, the airframe or the passengers?

Guess physically it would be the engines

Combination of Weight against lift available from the wings against thrust available from engines. Both lift and thrust drop off in thinner air until it'll climb no more.

I'm guessing the FBW system might not even let you try...

Service ceiling of the B777 is 43100 ft, but that would probably be at the lighter end of the cruise.

From a point of view of incapacitating your passengers, 37000 feet is as good as 45000 feet, though. You've already got the majority of the breathable atmosphere well below you by then, so it's a matter of seconds in either case. If oxygen masks deploy, they work on the basis that you'll descend in the event of a cabin depressurisation. Breathing pure oxygen at 37000 feet isn't enough to keep you conscious for long, and certainly not if you're going to mount a useful resistance to a hijacker as opposed to just remaining conscious.

[Rods2]

What determines the operational ceiling? Is it the engines, the airframe or the passengers?

Guess physically it would be the engines

Lift, thrust, and indicated airspeed: Lift and thrust where you can't climb any higher or if you get high enough where IAS decreases with altitude until it reaches the stall speed, so you stall, but you have plenty of altitude to recover.

[05omegav6]

What determines the operational ceiling? Is it the engines, the airframe or the passengers?

Guess physically it would be the engines

Lift, thrust, and indicated airspeed: Lift and thrust where you can't climb any higher or if you get high enough where IAS decreases with altitude until it reaches the stall speed, so you stall, but you have plenty of altitude to recover.

Unless you're driving an Airbus and haven't twigged that your instruments aren't functioning correctly

From what Entwood was saying over curry, climbing the aircraft and manipulating the cabin pressure is a pretty effective method of subduing the passengers... cabin crew training would kick in, so they might react to mask deployment more readily than sleeping passengers

Although whether they would do anything against the flight crew or not, I couldn't say unlikey I suspect...

Another issue with this is whether or not the valves on the cabin emergency oxygen system can be controlled remotely they must have valves for bottle changing purposes, but could there be an emergency override... imagine a cabin fire coinciding with mask deployment. Filling the cabin with oxygen would be devastating.

[Rods2]

Where they are claiming it climbed to 45,000ft the service ceiling is 43,100ft. I suspect even getting to this sort of altitude would take sometime, where the rate of climb will be very slow as it approaches its service ceiling.

[TheBoy]

Where they are claiming it climbed to 45,000ft the service ceiling is 43,100ft. I suspect even getting to this sort of altitude would take sometime, where the rate of climb will be very slow as it approaches its service ceiling.

A radar contact, known to be inaccurate for altitude, showed it at 45000'

[Entwood]

Where they are claiming it climbed to 45,000ft the service ceiling is 43,100ft. I suspect even getting to this sort of altitude would take sometime, where the rate of climb will be very slow as it approaches its service ceiling.

Remember that the "service ceiling" is the height to which the aircraft can climb and STILL MAINTAIN A (REDUCED) CRUISE SPEED....  if you "trade" speed for height it is extremely easy to exceed the service ceiling ... you just have very little forward airspeed, even at the service ceiling (by definition) the aircraft has a rate of climb. (if the grey cells are still working its 100 ft/min, "cruise ceiling" is defined as 300 ft/min capability)

The "absolute ceiling" is the height, (for weight and temperature) that with max power set and holding the speed known as the Minimum Control Speed, the aircraft reaches and has zero rate of climb. The Vmin (Velocity Minimum Control) is  higher than the Vstall (Velocity Stall) as, again by definition, at Vstall you have effectively lost control of the aircraft.

[05omegav6]

If the autopilot was set, with say a 500ft/min climb rate, whilst the crew set about switching various systems off, then would the flight management computer not simply maintain that climb rate until the airspeed dropped to a predetermined level Which would presumably be a higher speed than the stall speed... afterall, the program engineers at Bo(e)ing wouldn't install system parameters which endangered the aircraft

[cam2502]

Watching the news just now, Malaysian cops physically ejecting family members who wanted to talk to the media out of a press conference. Shocking scenes.
Why aren't they allowed to speak to the media? What are the authorities hiding??

[05omegav6]

Not a surprise tbh...

They have lost 240 people and several million dollars worth of aircraft, haven't the faintest idea where it actually is, and there is SFA that they can do about it

Had they come clean about that a week or so ago, then who knows...

I truly sympathise with the plight of the families, and of the Authorities, but there is very little information being released simply because there is very little information.

It is likely that the passengers are dead rather than holed up somewhere

The frightening thing in this whole conundrum is that no one seems to be even remotely aware of the elephant in the corner. The sooner that that reality is faced, the more likely they are to recover the aircraft and hopefully put the passengers to rest properly...

[Entwood]

If the autopilot was set, with say a 500ft/min climb rate, whilst the crew set about switching various systems off, then would the flight management computer not simply maintain that climb rate until the airspeed dropped to a predetermined level Which would presumably be a higher speed than the stall speed... afterall, the program engineers at Bo(e)ing wouldn't install system parameters which endangered the aircraft

Don't know the parameters of the 777 autopilot .. but on the old-tech Herc we would set a speed and the autopilot would (attempt) to hold that .. if the power was greater than that required to maintain speed, the aircraft would climb, if less it would descend, so climbing technique for max height was simply set climb power and bug in min climb speed ... the aircraft would continue to try and climb whilst maintaining the speed - and once at "max" height it would then actually still climb VERY slowly as the weight reduced due to fuel burn if you did nowt about it. Normal technique was to reach the required height then bug in that height and set the power to maintain target speed.

We had no "auto throttle" so were not able to bug both a height and a speed like the posh new stuff can with their auto-throttles ..