TransAsia ATR crash in Taiwan.

[Ginetta G15 Girl]

Eric Mc said:

The problem is when people like you resort to acronyms, abbreviations etc which make it seem like you are showing off and not trying to inform. When you write like that, are you TRYING to exclude others or do you genuinely think that we all understand what they mean?

It's not a question of me growing up.

It's a question of perhaps you being a bit more thoughtful of others.

Go back and read and bloody digest the thread.

You will find that in my first post I defined the abbreviations Vmca, Vr, and V2. Oh dear I failed to define Vmca1 but I would have thought anyone with half a brain would see that it a condition of Vmca! Appaently not. Oh dear, how fking sad, never mind.

You will further find that in my second post, not only did I define the abreviations (again, and this time defined Vmca1 and Vmca2) but I also explained their meaning.

So yes you do need to grow up and stop being such a prig.



Or maybe you need to see an optician.

[saaby93]

Eric Mc said:

Good, detailed explanations from people like you (like the above) are appreciated by people like me. The problem is when people like you resort to acronyms, abbreviations etc which make it seem like you are showing off and not trying to inform. When you write like that, are you TRYING to exclude others or do you genuinely think that we all understand what they mean?

or something else

Would they have tried to slow the good engine in line with the bad one to retain balance, when something else cut the good one?

[Eric Mc]

That would have been a very risky thing to try.

[Ginetta G15 Girl]

Le TVR said:

Thankyou G15

Given the autofeather system, would that start to re-pitch the prop and cause additional asymetric drag that resulted in the port wing dropping suddenly just before impact?

I have never flown the ATR so I am not certain of the sytems it uses.

However, to re-start a feathered prop the first thing you need to do is to unfeather it. Partly because you want the relative airflow to start the prop turning (AIRSTART) which (because it is attached through a gearbox) will start the engine turning, and partly because if you were using (say) the starter motor to turn the engine, you'd overtorque it trying to spin up the feathered blades.

In the AIRSTART case, as the blades come off the feathered position they will (whilst remaining static, ie prop not yet spinning) go through the Coarse Pitch position to the Fine Pitch position. As they start to reach Fine Pitch the prop will start to spin up. Assuming you now have fuel flow (ie fuel cocks open) and igniters running, the engine will light up (On Albert going to the AIRSTART position on the Condition Lever opened the HP Cock, set the igniters running and used the feather valve and aux prop pump to de-feather the engine).

The upshot of this is that, yes, as the blades come off the feathered position there is a rise in drag; initially profile drag while the prop is stationary and then induced (lift dependant) drag (negative torque) as the prop starts to spin up. The drag then falls away as the engine becomes self-sustaining and starts to produce (idle) thrust.

If you are already in a stalled, or close to stalled, condition this drag rise could vey well induce a wing drop such as we see here.

[Ginetta G15 Girl]

saaby93 said:

Or something else

Would they have tried to slow the good engine in line with the bad one to retain balance, when something else cut the good one?

No.

The data quite clearly shows that the No2 autofeathered after it flamed out (in exactly the way it is supposed to).

A minute later the No1 engine condition lever was moved to the fuel shut off position.

I would suggest that the initial retardation of the No1 power lever was the crew mis-identifying the failed engine and starting the No1 shut down drill.

[HoHoHo]

Ginetta G15 Girl said:

Interesting explanation

Thanks very much.

What strikes and frightens me is how quickly it all happens combined with a lack of altitude to help you really have only very few seconds to try and resolve the situation which is very quickly and before you know it becoming your worst nightmare.

[scenario8]

HoHoHo said:

Ginetta G15 Girl said:

Interesting explanation

Thanks very much.

What strikes and frightens me is how quickly it all happens combined with a lack of altitude to help you really have only very few seconds to try and resolve the situation which is very quickly and before you know it becoming your worst nightmare.

Isn't that one of the reasons so much time and money is invested in the crew and they're paid (relatively) handsomely?

Regardless, what a tragic incident.

[Eric Mc]

It looks like it all happened at just the wrong moment and they mishandled the situation. I hope that the CVR (Cockpit Voice Recorder) might throw some light as to what was going on in the cockpit.

[Le TVR]

I agree that this is mis-identification of the failed engine.

Given the information that this aircraft had a history of #1 engine problems and that that engine had been recently replaced, it seems like a case of assumption versus analysis?

[KTF]

From one of the posters on Pprune:

Pprune said:

Many years after I had line trained a first officer he reminded me of a simulated emergency I had given him. I don’t recall the details but apparently I said: “Sit on your hands Nick and don’t rush into doing the wrong thing”. Nick later told me that was amongst the best advice he had ever been given.

Kegworth? If they had done nothing, there would probably not have been a crash.

TransAsia.....?

[DrDoofenshmirtz]

There was an Air Crash Investigation episode where the co-pilot felt he couldn't (or felt he shouldn't) overrule the captain because he was more senior. I wonder if the same thing happened here (it was a similar part of the world IIRC).

Thanks for the detailed explanation BTW - very interesting.

[HoHoHo]

scenario8 said:

HoHoHo said:

Ginetta G15 Girl said:

Interesting explanation

Thanks very much.

What strikes and frightens me is how quickly it all happens combined with a lack of altitude to help you really have only very few seconds to try and resolve the situation which is very quickly and before you know it becoming your worst nightmare.

Isn't that one of the reasons so much time and money is invested in the crew and they're paid (relatively) handsomely?

Regardless, what a tragic incident.

I know a few EasyJet pilots who aren't paid a (relatively) handsome sum!

I was simply thinking - wow, that's a few seconds - I'm sure pilots with many hours are trained for exactly this situation in the sim (again so I'm told by friends) but it just happens sooo quickly.

[Cobalt Blue]

DrDoofenshmirtz said:

There was an Air Crash Investigation episode where the co-pilot felt he couldn't (or felt he shouldn't) overrule the captain because he was more senior. I wonder if the same thing happened here (it was a similar part of the world IIRC).

Thanks for the detailed explanation BTW - very interesting.

The First Officer might have been reluctant to query the Captain, but a senior instructor was on the jump seat. He, with his 16k hours would surely have said something. Plus, he was detached from the nuances of controlling the aircraft and free to observe both instruments and pilot responses.

I wonder if automation might be behind this (and Kegworth)? As No1 engine wound down, Pilot Flying would have needed a bootfull of left rudder to correct yaw -unless the ATR has some kind of auto-trim, keeping the aircraft straight and reducing sensory input to the crew?

A commentator on Aviation Herald mentioned that the similar Fokker machine had lights that flashed on the power lever of an engine if it failed. This seems like such a simple way to save lives.

[toppstuff]

HoHoHo said:

Ginetta G15 Girl said:

Interesting explanation

Thanks very much.

What strikes and frightens me is how quickly it all happens combined with a lack of altitude to help you really have only very few seconds to try and resolve the situation which is very quickly and before you know it becoming your worst nightmare.

Thanks to Ginetta G15 for her detailed and easy to understand explanation.

I travel on a lot of ATR aircraft. They are the most popular turboprop out there these days and growing in numbers all over the place - there really isn't anything better for carrying up to 70 or so people for journeys of 60 minutes or so. Hundreds of them are proliferating all over Asia.

I believe there are already 1300+ ATR in the air and they have a good record, so I don't think its a problem with the type.

Looks like a simple error on the flight deck.

Very unfortunate.

[Blaster72]

There seems to be some serious arse covering going on already - how often have you seen the traces from the flight recorders released just one day after an accident?

The pilots are all dead - perhaps and easy target to pin this one on straight away and hope its all quickly forgotten about.

The full accident report should make interesting reading if only to see how it compares to the amateur sleuthing already done on here and various other websites, lets just hope the truth comes and out and the real cause is identified.

[FourWheelDrift]

DrDoofenshmirtz said:

There was an Air Crash Investigation episode where the co-pilot felt he couldn't (or felt he shouldn't) overrule the captain because he was more senior. I wonder if the same thing happened here (it was a similar part of the world IIRC).

Thanks for the detailed explanation BTW - very interesting.

The first one I thought of was the replacement of an ATR-42 fuel gauge put into an ATR-72 mix up that resulted in the 72 being short filled, but that was with an aircraft in service a long time and after a few hours in the air. - http://en.wikipedia.org/wiki/Tuninter_Flight_1153 The Taiwan one was brand new and just taken off so that can be discounted.

[KTF]

Blaster72 said:

There seems to be some serious arse covering going on already - how often have you seen the traces from the flight recorders released just one day after an accident?

The FDRs were very easy to recover given the aircrafts final resting place. As soon as the data is pulled off they know what went on so why not release it given the attention focused on this.

[Jandywa]

Eric Mc said:

Ginetta G15 Girl said:

Oh do grow up!




Looking at the graphical data there appear to be 4 distinct timing points (I have interpolated the timings as best I am able from the limitations of the display).

Note No1 engine is the port, No2 the Starboard.


At 02:52:35 the following happens:

Master Warning Caption No2 Engine Flameout.
No2 Prop starts to go into the Beta range (indicating that it is correctly autofeathering.)
No2 Turbine Inlet Temperature (ITT) falls rapidly (indicating engine shut down).
No2 Overall RPM begins to rapidly drop (NP).
No2 Fuel flow shuts off.
No2 Prop torque begins to fluctuate indicating that the blade angle is rapidly changing (ie autofeather is occurring).
No2 LP Compressor RPM begins to fall (NL).
No2 HP Compressor RPM begins to fall (NH).

At 02:53:05 the following happens:

No1 Power Lever is retarded slightly (PLA - Power Lever Angle reduces), No2 is left at full power.
No1 Turbine Inlet Temperature (ITT) reduces .
No1 Overall RPM reduces slightly (NP).
No1 Fuel flow reduces.
No1 LP Compressor RPM reduces slightly (NL).
No1 HP Compressor RPM reduces slightly (NH).


At 02:53:25 the following happens:

No1 Condition Lever is moved to Fuel SHUT OFF (CLA - Condition Lever Angle).
No1 Prop starts to go into the Beta range (indicating that it is feathering).
No1 Power lever is fully retarded.
No1 Turbine Inlet Temperature (ITT) drops to minimum (idicating engine shut down).
No1 Overall RPM begins to rapidly drop (NP).
No1 Fuel flow shuts off.
No1 Prop torque begins to fluctuate indicating that the blade angle is rapidly changing (ie feather is occurring).
No1 LP Compressor RPM begins to fall (NL).
No1 HP Compressor RPM begins to fall (NH).


At 02:54:19 the following happens:

No1 Condition Lever is moved to the AIRSTART position (fuel shut off valve opens).
No1 Turbine Inlet Temperature (ITT) starts to rise.
No1 LP Compressor RPM begins to rise (NL).
No1 HP Compressor RPM begins to rise(NH).


So, No2 engine fails at around 02:52:35, about 30 seconds later power on No1 engine is retarded. About 30 seconds after that, No1 engine is shut down. About a minute later a relight attempt is started on the No1 engine.



If we couple this with the report of a left wing drop at around the time the No2 failed, as well as with the speed read out from Flight Radar 24 it is apparent that:

The crew mis-identified the failed engine, retarded the live, then shut down the live engine. They then tried to relight the engine they had shut down.

Up to the failure of No2, the rate of climb is around 1500 fpm dropping by about half fom the point of failure until the live engine is shut down. More significantly, the airspeed is decaying to 100 kts when the No2 fails, it then rapidly decays further before stabilising(ish) - looks like the nose was lowered.



This is mere supposition but I would suggest that it is possible that they mis-handled the climbout and possibly stalled the left wing at around the time the engine Master Caption illuminated (accelerated stall). The wing drop led them to believe it was a No1 failure so they shut it down. From that point the inevitible happened.

Edited by Ginetta G15 Girl on Friday 6th February 14:31

Good, detailed explanations from people like you (like the above) are appreciated by people like me. The problem is when people like you resort to acronyms, abbreviations etc which make it seem like you are showing off and not trying to inform. When you write like that, are you TRYING to exclude others or do you genuinely think that we all understand what they mean?

It's not a question of me growing up.

It's a question of perhaps you being a bit more thoughtful of others.

G15's explanation was very easy to follow and understand imo I don't see the issue.

[Munter]

Blaster72 said:

There seems to be some serious arse covering going on already - how often have you seen the traces from the flight recorders released just one day after an accident?

The pilots are all dead - perhaps and easy target to pin this one on straight away and hope its all quickly forgotten about.

The full accident report should make interesting reading if only to see how it compares to the amateur sleuthing already done on here and various other websites, lets just hope the truth comes and out and the real cause is identified.

The graph might tell us the pilots took the wrong actions.
But why?
If we answer that, then we are left asking why the earlier event?
And so on and so on.
The "real cause" could depend on how far down that line of questioning you want to go/manage to get before stopping.

[Blaster72]

KTF said:

Blaster72 said:

There seems to be some serious arse covering going on already - how often have you seen the traces from the flight recorders released just one day after an accident?

The FDRs were very easy to recover given the aircrafts final resting place. As soon as the data is pulled off they know what went on so why not release it given the attention focused on this.

There is absolutely no reason to release this sort of information quickly without carrying out any sort of investigation - the media can wait. An FDR will never tell the full story without looking at the rest of the facts.

I can't see the UK Air accident investigation branch ever releasing such data less than 24 hours after a crash like this and firmly pointing the finger at the operating pilots.