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Lottie

Airliner Crash Lands at Heathrow Airport

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Unlimited
I just thought that if remote access is a worry for new planes then it could certainly be a worry for old planes.

the plane in question was top of the line ....i think everyones baffled...

Edited by Unlimited

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keithisco

Electro magnetic burst would have to be extremely focussed or else it would have taken out every plane, car, truck in the vicinity Dont think the technology is readily available. I am still surprised that the engines did not respond to the manual control though :huh: The Fly-By-Wire and manual signals are doubly redundant and isolated from each other.

Could be a wiring fault?

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Electro magnetic burst would have to be extremely focussed or else it would have taken out every plane, car, truck in the vicinity Dont think the technology is readily available. I am still surprised that the engines did not respond to the manual control though :huh: The Fly-By-Wire and manual signals are doubly redundant and isolated from each other.

Could be a wiring fault?

A burned out main fuse?

It is right that fly by wire has redundant mechanical controls, but it takes a while to enable them. Even if the biggest bus I ever flew was only a King Air I would have hated an engine shutdown on final. Getting out of that without a black eye is extremely difficult. At the point of the shutdown the plane was only minutes away from touch down, no time for plan B.

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keithisco
A burned out main fuse?

It is right that fly by wire has redundant mechanical controls, but it takes a while to enable them. Even if the biggest bus I ever flew was only a King Air I would have hated an engine shutdown on final. Getting out of that without a black eye is extremely difficult. At the point of the shutdown the plane was only minutes away from touch down, no time for plan B.

A burned out main fuse? I think you are having fun now :D

You are right about the enabling time, although in most modern commercial airliners it is no more than 50mS, however, the turbine reaction time (and ability to increase thrust) is very much longer and as you also say I think he was committed on the glideslope and probably only had a very short window to correct the thrust. Still did a fine job of landing though. I was wondering if the control surfaces on the wings froze as well causing it to descend faster than optimal???

Well, we will definitely know from the black boxes when they have been downloaded

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Atheist God

Man it would have been pretty trippy to be on that plane.

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A burned out main fuse? I think you are having fun now :D

You are right about the enabling time, although in most modern commercial airliners it is no more than 50mS, however, the turbine reaction time (and ability to increase thrust) is very much longer and as you also say I think he was committed on the glideslope and probably only had a very short window to correct the thrust. Still did a fine job of landing though. I was wondering if the control surfaces on the wings froze as well causing it to descend faster than optimal???

Well, we will definitely know from the black boxes when they have been downloaded

Part of the glideslope component is you rest-thrust. You don't shut off engines to idle until you are about to set the the wheels on the ground. At any time before decision hight you have to be able to abort landing and at any time be able to respond to a go-around order from the tower. As soon as the engine is shut off you fall 10-15% faster than with the rest trust (if set right).

Additionally, on many bigger buses hydraulic and vacuum control aids play a big role. Without engines no pressure and/or vacuum and back to the traditional Jack-the-Ripper methods.

But as you said, we won't know all until we see the boxes decoded.

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Moon Monkey

I was just wondering (while we wait for black box details), do the autopilot and the manual pilot use the same actuators for thrust, what are the redundancies on these and are they totally hard wired ? Also are there any automatic switch-offs on the engines for things like fires and if so what sensors would be used, how are they activated and are these hard wired as well ? I wondered because all the rports from "aviation experts' in the sunday papers say it must have been an automatic control command that shut both engines down at once.

Edited by Moon Monkey

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I was just wondering (while we wait for black box details), do the autopilot and the manual pilot use the same actuators for thrust, what are the redundancies on these and are they totally hard wired ? Also are there any automatic switch-offs on the engines for things like fires and if so what sensors would be used, how are they activated and are these hard wired as well ? I wondered because all the rports from "aviation experts' in the sunday papers say it must have been an automatic control command that shut both engines down at once.

The short answer is yes, unless we talk the newer airbus models, for the actuators. In fact it is very funny to see the throttle levers moving up and down as by ghosts hands. And as far as I know, no, there is no such thing as an automatic shutdown, to avoid situations as the one at hand. To shut off a turbine you set it to idle and then switch off the gas supply. In case of fire you skip the setting in idle part and pull the gas cocks and extinguisher switches, sometimes the extinguisher switches also cut the gas supply, but not on every aircraft. I am not sure that in the triple 7 the extinguishers are wired to the gas stops, if so it could be a likely situation that the extinguishers were actuated, but not likely that both were actuated at the same time.

Either switching off gas by accident or the extinguishers by accident is quite unlikely because there are several mechanical safeguards against that.

So that leaves mechanical malfunction if the gas supply was cut, which to me is more worrying than human error.

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Unlimited

an alien ship can take down an airliner like that i've heard...lotta ufo sightings around england too...just a thought.

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goalienan

Good calm thinking by the pilot. What a horrible fear to know you have all these passengers lives in your hands....The day before I flew to Atlanta, two Continental airlines just missed each other while landing, and now up here in Newark they're saying that Air Control needs to be fully reconstructed...Scary as hell.....

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ships-cat

The Sunday Times had a big article on this, and it also mentioned that the engines are pretty much seperate: seperate fuel tanks, control circuits, throttlles... the only common factor is the flight management computer.

Does anyone know: did the engines actually spool down, or did they simply "stick" at a certain power setting and refuse to change ?

Cats initial recommendation: seperate the systems even further. Install the left and right engines onto different aircraft , that way if both spool down simultanously, then the individual aircraft will each still have one functioning engine.

Simple really :D

Meow Purr.

Edited by ships-cat

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The Sunday Times had a big article on this, and it also mentioned that the engines are pretty much seperate: seperate fuel tanks, control circuits, throttlles... the only common factor is the flight management computer.

Does anyone know: did the engines actually spool down, or did they simply "stick" at a certain power setting and refuse to change ?

Cats initial recommendation: seperate the systems even further. Install the left and right engines onto different aircraft , that way if both spool down simultanously, then the individual aircraft will each still have one functioning engine.

Simple really :D

Meow Purr.

Sounds good, how about just having flight management totally switched off for take-off and landing reverting to total manual. Many pilots just switch on autopilot and hope that nothing goes wrong... but we all know Murphy's law.

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ships-cat
Sounds good, how about just having flight management totally switched off for take-off and landing reverting to total manual. Many pilots just switch on autopilot and hope that nothing goes wrong... but we all know Murphy's law.

It appears that is not an option on this type of aircraft. There are no physical connections between the yoke, throttles etc and the actual control surfaces (aerolons, rudders, flaps etc etc). The pilot HAD disengaged the autopilot/autothrottle, but still had no control over engine thrust.

Meow Purr.

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It appears that is not an option on this type of aircraft. There are no physical connections between the yoke, throttles etc and the actual control surfaces (aerolons, rudders, flaps etc etc). The pilot HAD disengaged the autopilot/autothrottle, but still had no control over engine thrust.

Meow Purr.

And here we are again: People putting themselves at the mercy of a single fuse....

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Moon Monkey

This is what I was questioning earlier...it doesn't seem to matter whether its manual or autopilot as it is the same signal sent 'fly-by-wire' so with or without redundancies if the reference input is zero thats what you will get as all the redundant actuators/sensors will agree and be unable to vote on a faultly component or signal, which is what they would usually do.

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This is what I was questioning earlier...it doesn't seem to matter whether its manual or autopilot as it is the same signal sent 'fly-by-wire' so with or without redundancies if the reference input is zero thats what you will get as all the redundant actuators/sensors will agree and be unable to vote on a faultly component or signal, which is what they would usually do.

Depending on the aircraft model: yes. There are some that can be flown by classical pulley actuation once the wire fails, Boeing in fact advertises this capability of a triple 7 (see: http://seattlepi.nwsource.com/business/boe202.shtml).

The better question is: What happens if the actuator blocks, do the pulleys also block?

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Moon Monkey
Depending on the aircraft model: yes. There are some that can be flown by classical pulley actuation once the wire fails, Boeing in fact advertises this capability of a triple 7 (see: http://seattlepi.nwsource.com/business/boe202.shtml).

The better question is: What happens if the actuator blocks, do the pulleys also block?

Is that right ? I got the impression that they keep the old yokes purely because pilots like the 'feel' but still use fly-by-wire for performing the actions.

Btw having a look around I saw an article about a 777 in Australia that was presenting the wrong data to the autopilot but manual control was still possible which prevented disaster.

http://www.airlinesafety.com/faq/777DataFailure.htm

I am smelling a software glitch.

Edited by Moon Monkey

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Is that right ? I got the impression that they keep the old yokes purely because pilots like the 'feel' but still use fly-by-wire for performing the actions.

The only one that "feels" different is the Airbus, it has in fact two little joysticks not unlike those of a computer game. But if they should fail you can mount a mechanical emergency stick (providing you have enough time left before hitting the ground). Those systems are redundant for pilot and co-pilot so that the failure of one does not influence the safety.

The throttle array is the same classic one for practical reasons. You need the same setting as the one with the autopilot had once you switch it off. Besides, the throttle actuators themselves do not require much force to operate (unless the pulleys are rusted, which should not happen). Some of them even have a adjustable friction brake to give a sensation of resistance when operating.

ED: Ehm, I would not be surprised at a programming error either.

Edited by questionmark

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keithisco

This really is mystifying....

If there really is a SPF (Single Point Failure) mode in the aircraft (i.e. a failure that can ocurr with no redundant back-up) then that is of huge concern!

I find it hard to believe though because FAA and EASA Type Certification exists in large part to prevent just that.

The cockpit would have been alive with just about every warning flashing and sounding, Ground Proximity warning , ECAM warnings, etc. The aircraft made an asymetrical heavy landing witnessed by just one of the Landing Gears to give way, this suggests that some loss of control surface also ocurred, but then again that could have been due to wind shear. Will try to get the wether report for heathrow at the time, and determine what the Flight Rule prevailing was.

Another possibility that is a potential SPF is fuel contamination, it would certainly have been fuelled up in Beijing with JetA1, still just guessing though

I really have no idea, this is one bizarre incident

Edited by keithisco

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This really is mystifying....

If there really is a SPF (Single Point Failure) mode in the aircraft (i.e. a failure that can ocurr with no redundant back-up) then that is of huge concern!

I find it hard to believe though because FAA and EASA Type Certification exists in large part to prevent just that.

The cockpit would have been alive with just about every warning flashing and sounding, Ground Proximity warning , ECAM warnings, etc. The aircraft made an asymetrical heavy landing witnessed by just one of the Landing Gears to give way, this suggests that some loss of control surface also ocurred, but then again that could have been due to wind shear. Will try to get the wether report for heathrow at the time, and determine what the Flight Rule prevailing was.

Another possibility that is a potential SPF is fuel contamination, it would certainly have been fuelled up in Beijing with JetA1, still just guessing though

I really have no idea, this is one bizarre incident

Engines don't fail simultaneously due to fuel contamination, there can be hours of difference between failures.

Been checking around if someone I know has a maintenance manual for the triple 7 (I know, for $300 you can buy one... but I don't really need it). If it all happened due to power loss that means that there is a solenoid in the fuel supply line that only stays open while powered, which if you ask me is a engineering short come to start with, once started a turbine does not need any electricity to keep functioning (at least for a while).

But it is really mystifying...

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Unlimited

could it have been sabotage?....

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Space Commander Travis
this is turning into quite the conspiracy?....wasnt it a planeload of communists?...hmmmmmmmm

I expect the communists would probably choose Air China.

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Unlimited
I expect the communists would probably choose Air China.

who owned the plane?....the article doesnt mention..

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Space Commander Travis

British Airways.

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Moon Monkey

BTW due to the landing patterns at Heathrow had this loss of power happened a few minutes earlier it would have been coming down in central London.

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