Turkish airliner crashes at Schiphol

[fireflybob]

2 Both crews noticed speed going below Vref and both attempted corrections with thrust adjustments

S.F.L.Y., so you think the crew on the Turkish incident noticed the speed going below Vref? Then why didn't they apply additional thrust at a much earlier stage?

[clivewatson]

S.F.L.Y

I am not sure what kind of axe you are attempting to grind, but you seem to be alone in your effort to do it with a blunt object!

From the information currently available, it appears to me that the BA crew responded to an actual loss of thrust in the most appropriate manner by retracting the flap setting to enhance the glide performance, thus bringing the AOA closer to that for "best glide." I suspect that they did not have sufficient height to achieve the ideal AOA for the a/c weight and configuration, but their reaction to a scenario for which they had not been trained certainly improved the glide performance by some degree - and probably by just enough to change the outcome.

The Turkish crew, based on what has been published to date, appear not to have responded in any way to a situation that was unfolding gradually over a period of 100 seconds. The Turkish crew also had thrust at their disposal should they have deemed it necessary to use!

[chuks]

Well, you try this and see how well you do!

You can nitpick all you like with "coulda-shoulda-woulda" in either case and come away telling anyone who will listen to you how you would have done this so much better but many of us will just think, "Oh, really?"

I have been on a few sim sessions with some self-nominated "ace of the base," someone ever-ready to jump in with a critique of the minutiae that went overlooked in managing a serious problem over a very short span of time by some other crew. Then our ace gets handed a surprise of his own, when he shows that he too might not be Superman, when this sad fact is not a surprise.

I happen to have a Commercial Glider License so that I think I know a bit about gliding flight and in a glider I hope I can apply those principals properly. On the other hand I also have an ATPL so that I think I know how to do a powered ILS approach, although I have never flown such a large jet as a 777. Just where in these two very different things is my qualification and experience suddenly to switch from a powered to a gliding approach on short final in a large jet transport aircraft, though? What that BA crew was faced with was so far off the scope that its very probability is not accounted for and simply to have managed a safe landing was an extraordinary feat, hence, one supposes, the gold medal they were awarded.

Arrogance is sometimes justified; it isn't always a bad thing to say, "I can ride that wild bull through a china shop," if you can pull that feat off when most of us cannot but it's still arrogance.

[S.F.L.Y]

From the information currently available, it appears to me that the BA crew responded to an actual loss of thrust in the most appropriate manner by retracting the flap setting to enhance the glide performance, thus bringing the AOA closer to that for "best glide."

Reaching stick shaker obviously demonstrate that the AOA wasn't controlled in a way to enhance the glide performance. Since the AP was following the ILS the AOA didn't stop increasing, very far from best glide. Retracting flaps doesn't lead to AOA reduction (on the contrary if you wish to maintain a constant path), it only improve drag.

[barit1]

If there were some way the BA038 crew could have been alerted to the magnitude of the problem early on, SFLY's theories might have mitigated the outcome. Unfortunately the onset of the problem was subtle and probably not recognized for 15-30 seconds - there is that long a time constant in the response of a 250 tonne aircraft.

The real world sometimes won't behave like the book.

[moonburn]

Don't feed the numpties and they will eventualy go away. I don't know about the rest of you but SFLY is on my ignore list as of now.

[S.F.L.Y]

Having different points of view isn't an issue. I find interesting to notice that in both scenarios crews took manual control of the aircraft when no energy was left to prevent a high Vz fall. fortunately for the BA crew enough height was available to reduce this Vz prior to the impact. Understanding the mechanisms that delayed the manual override is very important since it is precisely what led both aircraft to enter a somehow uncontrolled* high Vz descent close to the ground.
*which is precisely why I don't understand how this could be an heroic issue in one case and a fault in the other...

[fireflybob]

Reaching stick shaker obviously demonstrate that the AOA wasn't controlled in a way to enhance the glide performance. Since the AP was following the ILS the AOA didn't stop increasing, very far from best glide. Retracting flaps doesn't lead to AOA reduction (on the contrary if you wish to maintain a constant path), it only improve drag.

So S.F.L.Y., please tell us what you would have done so we can benefit from your superior knowledge!

[S.F.L.Y]

So S.F.L.Y., please tell us what you would have done so we can benefit from your superior knowledge!

It's not that I'd have done better, I might have done the same, but since it's far from being optimum I'm interested to know why I would have adopted an underperforming strategy.

This was already discussed in the other thread, if you consider Vref close to best glide speed, variations will deteriorate the performances. Since the AP was constantly increasing the AOA to maintain a wrong path, gliding performances were constantly reduced until reaching their minimum (stick shaker). By reaching the stick shaker they basically reached the worse gliding performances they could achieve below Vref...

[fireflybob]

This was already discussed in the other thread, if you consider Vref close to best glide speed, variations will deteriorate the performances. Since the AP was constantly increasing the AOA to maintain a wrong path, gliding performances were constantly reduced until reaching their minimum (stick shaker). By reaching the stick shaker they basically reached the worse gliding performances they could achieve below Vref...

I think it's almost a case of "programming" - we are most use to what is "normal" and, even with the most prepared pilot, you have to add the "factor of disbelief". Part of the programming is not to go low on the approach! The first step in solving any problem is the acquisition of the correct information. Pilots have to make their decisions in real time. This crew was faced with an extremely rare situation - you might expect one engine to fail on final approach but not both at the same time.

[infrequentflyer789]

Originally Posted by S.F.L.Y

Having different points of view isn't an issue. I find interesting to notice that in both scenarios crews took manual control of the aircraft when no energy was left to prevent a high Vz fall. fortunately for the BA crew enough height was available to reduce this Vz prior to the impact.

[sorry, I know "don't feed" etc., but...]

This is plain wrong. BA038 started to have problems (one engine) at 720ft, lost thrust on both at about 600, and realised they had a dual engine failure at 480ft. They then started trying to get engines back. AP stayed in until below 200ft, stick shaker below that.

The other crew had warnings of problems at "high altitude" (see report), thrust retarded at 2000ft, unnoticed (it appears) until stick shaker at 460ft.

So, which crew had more height to recover with (460 or <200) ?
Which crew also had thrust to recover with ?
...and which crew managed to get the plane down on the grass such that some pax didn't even realise they'd crashed ?


BA crew didn't "fortunately" have "enough height" - they had less (at stick shaker) than the THY crew, and no engines. They simply flew a lot better with what they had.

[chuks]

The best one ever!

I was doing my post-flight paperwork when I noticed a young man stood there on the ramp peering intently at me through the little document hatch, so that I asked him if I could help him with something.

"That was a very bad landing!" said he.

Well, it had been the FO's landing anyway but it had been perfectly normal, one of those firm ones we are told to do nowadays so that the WOW switches tell the spoilers to come out and the engines to go to ground idle, tell the brakes to start working, all those minor details that go to make up a roll-out from a firm landing instead of an over-run into the bushes from a soft one.

"You must be new here," I replied.

"Why is that?"

"If you had flown with me much you would know that when I really make a bad landing I break the lightbulbs in the airport café!"

After a long silence he replied, "I still think it was a bad landing you made."

"Yes, and is there anything else I can help you with today? No?" I turned back to my paperwork and when I looked again he was gone.

It was lucky for him that I am so snobby and indifferent to opinions such as his; if I had really cared then I probably would have said, "Come a bit closer to the little window; I am hard of hearing," and then stuck two fingers in his eyes in the manner of Moe from "The Three Stooges."

[Dani]

The difference with THY and BA038 is that the Turkish crew was in a stall regime while the BA crew landed it "softly" into the ground. You make much more out of it if you try a normal landing outside a runway than if you stall the plane. That's why the outcome of BA038 was so much better.

To the benefit of the THY crew one has to admit that the 737 has less low speed protections than the 777.

Dani

[PJ2]

"Come a bit closer to the little window; I am hard of hearing," and then stuck two fingers in his eyes in the manner of Moe from "The Three Stooges."

Yep, good one.

Wx was < 1200' at destination, no CatII (this was 35 years ago), hand-flew the '9 down to about 200', nothing seen and returned to the departure airport - had one passenger tell us as he was getting off that "we just went up and flew around a while to keep everybody happy" before returning.

There's a million stories and everyone's an expert until they're called upon to perform.

FWIW, I think everyone seriously considering this question should read PBL's contribution very carefully before launching.

PJ2

[bearfoil]

BA038 Well. From Google I saw no evidence of a tail plant, all I saw as evidence of its arrival were two trenches caused by the main landing gear settling into the turf. These parallel "trenches" seem rather 'normal' for most of a quarter mile, at which point the right main dug in, failed, and was followed by the left gear. Slewing to the right, the a/c settled onto its engines, turned further right, then stopped. Like the Umpire says, "SAFE". But for the "short" all is well. As critical and sarcastic as I like to be, I have nothing but admiration for the Crew, in all respects. Wait, isn't this the Turkish thread?

bear

[S.F.L.Y]

Dani made an excellent remark, the Turkish aircraft stalled while BA038 recovered while in both cases manual override was initiated in similar conditions. According to the report following AP override the 737 attitude went 8 degrees below horizon before increasing to 22 above horizon. This probably results from the combination of a full nose up trim with application of max thrust which momentum couldn't be stopped by pitch inputs (similar as for the Perpignan A320 accident).

The remark about the low speed protections is very relevant as the 777 and the737 were certainly not trimmed the same way when crews took manual control. While the 777 could be recovered after stick shaker activation, the 737 entered pitch oscillations and stalled as full power was set.

Do you seriously think that swapping crews between these 2 aircrafts would have changed the outcome once stick shaker was reached??

[Smilin_Ed]

Wingview Got It Right

Wingview got it right when he said:

As far as I know, they did (or one of them) gave GA trust to recover (when the stick shaker came in), but the lever went back to idle again and that they didn't notice until too late (low).

That's right they didn't even notice.


As for S.F.L.Y., I suggest we all just ignore him.

[Ginetta]

Quote:-
"Do you seriously think that swapping crews between these 2 aircrafts would have changed the outcome once stick shaker was reached?? "

I think you are missing the point.

The crew of BA038 would have noticed the airspeed decaying below 'Vref' and taken remedial action before stickshaker activation.

[seat 0A]

The THY crew managed to crash a perfectly airworthy aircraft. The BA crew were performing their best efforts in a 777 without engines. They did so admireably well.
Big difference. No comparing the two.

[S.F.L.Y]

The crew of BA038 would have noticed the airspeed decaying below 'Vref' and taken remedial action before stickshaker activation.

In that case why didn't they take remedial action before stickshaker activation in their own 777?

I'm not saying the Turkish crew hadn't a serious lack of monitoring, I'm saying that both aircraft (for different reasons) reached stick shaker at low levels. At that particular point, swapping crews wouldn't have changed much of the outcomes.

A lot of people to mention BA's crew did so admirably well, but no one to elaborate on what they have done better that any other crew. I think most crews would have done the same (disengaging AP at stick shaker and flare what can be flared...). What could non-heroes have done different from that?