cats_five:
unfortunately i fly nothing real, just the ms sim + good share of SLF
i am qualified mechanical engineer specializing in control systems, with open mind and deeper than average knowledge of physics (including fluid mechanics)

and in my free time i am carefully reading different threads on this forum ;)

FYI my answer was supposed to be based on energy conservation law + B777 data available from Interim Report + some other data available in the net. In short: lowering the nose earlier would result in landing earlier because it would increase ROD so in fact shorten time in the air (flying time).
I have learned my lesson studying the AF477 case so i thought that it would be more beneficial if i just remind what the others, more experienced pilots, have already said on the subject.

CONF iture:
well, do you really believe that the person who has flown the sim just pulled the stick to stall the plane? or maybe he was trying his best to fly as far as possible by trading the speed for distance?
i do not know if the engines were running idle (as you say) or just failed (as it is written) but IF they were producing ANY thrust this was adding energy to the system and this SHOULD enable flying further - yet the outcome and landing point was similar.
By the way, do you have any idea how many pilots have tried to replicate this landing? Have you heard about any of them getting better results?

this IS judgement...

misd-agin:
you mean from 118kts F30 down to 108kts F25 - do you happen to know what would be the speed if they would have stayed with F30? Suppose they would have stayed with AP on : would the speed be higher? Or maybe even lower as the control surfaces would have to be trimmed more to maintain the AoA the AP was trying to keep?

but there was a perfect flare! Actually it was LANDING rather then CRASH. Passengers have described it as 'rough' but still landing. See the experience of the reporters who were looking for sensational passengers crash stories - and failed ;)

In short: this is crap.

First of all nobody mentioned lowering the nose. Not raising it would already be enough to improve gliding performances.

You think that the longer you stay in the air the further you go and that's wrong. Gliding faster will bring you on the ground earlier, but the extra speed you have will take you further, even with a reduced flight time. That's what best glide speed is all about.

It works just the same on helicopters during an autorotation. To go further you need to dive.

You call a 1400 fpm impact a landing? Do I need to remind you that the landing gear went through the wings? A perfect landing is when you touch the ground at Vs with almost no Vz. In this case they had high Vz and were close to Vs, in other words no way to flare.

Wojteksz please leave the room

Actually I like the way they put it : "Aircraft damaged beyond economic repair"

WojtekSz, if you're ready to invest some money, go and hire a flight instructor in Warsaw who could demonstrate what it's all about. A Cessna will do just fine and pick up a windy day, result will be only more telling.

Tarq57 - "The only option the crew seemed to have was to reduce excessive drag (reducing flap a bit) and maintain an airspeed that would allow a controllable impact. "

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Are you a professional pilot?

Aircraft have best glide speeds. Typically approach speeds are slightly slower than L/D to allow a slighter higher power setting. Slowing below best glide speed shortens your gliding distance(we'll skip the arguement about min sink with tailwind...).

"Reducing excess drag" - I've yet to see an official statement stating if total drag decreased or increased, and it's impact on gliding distance, by selecting Flaps 25 instead of leaving them at Flaps 30.

The flight was at Vref 135 kts with Flaps 30.
If slowed to 118 kts Flaps 30.
Flaps 25 were selected.
It slowed to 108 kts Flaps 25.
At 108 kts it couldn't slow anymore due to AOA protection from the FBW flight control system. So the sink rate increased. At that point everyone was along for the ride.

The arguement is 135 kts Flaps 30 gliding performance better than 118 kts Flaps 25? I don't know the answer for a fact. However, based on all my training, civilian, military, corporate, airline, to include heavy jet flying, fighters, and gliding, I'm inclined to believe Vref Flaps 30 is the correct choice. Unfortunately that is a scary view out the front windshield. I've done it in the simulator, which is a long way from real life, and it wasn't pleasent.

Every professional pilot knows that gliding performance was better at 118 kts Flaps 25 than it was at the AOA limit with 108 kts. Higher and higher AOA does not improve your gliding performance when you are slower than L/D.

The flight crew took one action that the aircraft would not have done by itself, that is the retraction of flaps 30 to flaps 25. Other than that there's a very good chance the aircraft would have hit in the exact same location if there were no pilots.

None of these two options happened. The flight ended at 102 kts flaps 25 (with headwind...) which is quite far from flaps 25 best glide speed corrected for the wind (probably more than 35 knots of difference). Since there was no time to accelerate to best glide speed, maintaining the speed at the moment flaps 25 were selected (118 kts) would still make a significant difference, especially on that side of the curve.

It doesn't suprise me in the least you don't fly, it does suprise me that given your academic background you continue to peddle a load of twaddle. Did you actually read the Wikipedia links I provided?

Suggest you take up flying gliders - real ones. You will learn far more about flying doing that than you will here or on the simulator.

What the storry is all about
 

Hello WojtekSz (and many others without real insight of "dead stick" landing)

Like many "High Academics", you apply mathematics to simplified models of the real world. That is, in essence, "theory".

Most flying theories about "best gliding" do not take into consideration transient effects :

- wind gradient close to the ground (500 ft and below)
- ground effect during the flare.
- "cushionning" effect of flaps (very little documented indeed)
- techniques for stretching the flare

Well trained pilots know better about that than highly educated university teachers ... Birds also, despite their small brain, know better ...

Had the so called flying pilot reduced flaps setting much earlyier, and had he kept the speed at a decent value, disregarding the religion about maintaining glide slope, the following would have happenned :

- initially, the aircraft would have lost somme altitude, descending below glide slope, aiming at a point short of the airport fence
- in this configuration, the aircraft would have flown at a better efficciency and lost less energy per mile travelled.
- reaching lower layers sooner, that is also meeting less head wind hence more efficiency again.
- when approching the ground or obstacles, it was then appropriate time to bleed airspeed and to "stretch the glide". This glide stretching is more spectacular in ground effect and low head wind than at 300 ft with full head wind and full induced drag.
- if the pilots had real good feeling, they should finally reset full flaps at the correct time just before impact.
- this "impact" whoud have happenned at minimum speed, but following a much improved angle of arrival and rate of descent. With some luck, the flare would have allowed a "no-accident" arrival, on the runway or shorthly before.

In any way, it was difficult to imagine a worse course of action than letting the speed going out of control, and reducing flaps when the aircraft was already very close to the stall. Ok, they finally avoided the stall, but the aircraft fell out of the sky, without any speed margin for a minimum flare.

_ _ _ _

In this very unusal situation, the captain did apply the normal procedure : let the copilot fly the aircraft, and try by himself to solve the problem. This was not a mistake. Many of us have done that, in the sim or in the real world. Unfortunately, the captain didn't succeed in restoring thrust, and the copilot forgot what "flying the aircraft" means - instead he just let the auto-pilot fly the ILS "as usual", until the last moment.

Not recognizing soon enough that an exceptionnal problem justifies throwing out all SOPs ... and applying instead basic airmanship, basic flying skills : this is what the storry is all about (regarding crew actions, and regarding company training as well).

Edit : "decent speed" instead of descent speed

In that kind of weather, some margin about normal Vref should be applied, isn't it?

And there was me reading this thread wondering how he could continually peddle the erroneous content in his posts when any pilot understands what rapidly happens to drag when increasing the AoA and on the back end of the drag curve and suddenly all becomes clear!

I can only speak for my airline and the B777 but with autothrottle engaged the answer to your question is no.

sudden recovery
 

non-pilot/non-sim

could anyone advise what the response of the a/c would have been had the blockage(s) suddenly cleared ? Would power start to increase to the freed engine(s) ?

Yes. However from idle or thereabouts the acceleration response is sluggish until the engine reaches a certain speed where acceleration is more or less instant.

It is one of the reasons immediately prior to take off that you will notice an aircraft's engines accelerated from idle to a low power setting followed by a brief pause for the engines to stabilise before the required take off power is applied.

Bis47
 

Not so in all 737 models 200 to 900, 757, 767 and 777 according to Boeing SOP's when the A/T is engaged. The A320/319 (and other buses I believe) use a feature called 'ground speed mini' which could be quite startling in very strong winds!


Regards
Exeng

Alleluiah !!!
 

At least someone who understand and who has practical experience of what we are talking about!

Woodpickle, I'm not rated on the 777 but handled 16,000 ft of engine out glide in IMC with in a fully iced aircraft. Do I qualify to post in this thread?

Eleven years of military flying on both fixed wing and rotary machines gave me the opportunity to perform 1h sessions every three months of dead stick landings or autorotations in various configurations.The procedure described by Bis47 is exactly what is supposed to be done and what actually works best. I don't think this experience comes within the 777 TR package...

Bis47,

I think the majority of what you're saying is accurate, even essential reading for when you end up in a forced undershoot situation. However, I do think it unrealistic to expect many airline pilots to have encountered/practiced this scenario - why should they? Most of us have only flown powered aircraft and there is very little, if any, formal training on how to counter a developing undershoot in the way you suggest (correct, IMHO). It's mostly "bar talk". The emphasis is on getting the approach right in the first place.

Again, I agree with the sentiment but the reality is that in the last minute of an (uneventful) 12hr flight, it takes even the Yeagers of this world a short time to work out just what the **** is going on. Remember, the engines were still running and there were no warnings, messages or alerts.

Regarding training, we practice approaches with all engines operating, one out and none at all, not with both stuck on random thrust. I don't see how that could be done any differently as scenarios such as the BA38 are so sensitive to weights, timings, wind, etc. that there is little to take away to apply to a generic class of failure. Also, bear in mind a) the statistical rarity of such events, leading to poor training 'value' and b) the understandable reluctance to run a simulator exercise where a crash is a likely outcome. With limited time and money, most companies concentrate on things that are breaking aircraft regularly, like 'rushed' approaches, CFIT, etc.

If the failure had occurred a minute earlier, they'd have probably been at F20 and Vref20 + a bit. The power settings the engines froze at were just enough to allow a stable approach in that configuration, even an autoland. Hey, if they'd closed the TLs instead of firewalling them, they'd have got the thrust back shortly afterwards as the ice melted on the FOHE faces... but no-one knew that at the time.

Fuel Flow Indications?
 

Does anyone know what the fuel flow was? Although they probably wouldn't have thought to look at the fuel flow, that would have given them a clue. This, of course is hindsight. I assume that is recorded of the flight recorder.

That GS mini feature could have well provided a nice 20 extra knots when most needed.
Would be really curious to simulate and analyse a similar scenario in a 340 …


Report says FF were at 5 and 6000 pph ...

bis47: the transient effect are really very interesting, still i will always prefer to fly higher and slower than faster and lower ...

especially over traffic on A30 ;)

Gentelmen, thank you for most interesting time, pls excuse me if you feel that it was a shade ;) too much speculative

Fuel flow is not one of the primary engine indications (EPR, N1 & EGT are). At that point on the approach, the handling pilot would have had his hand resting on the thrust levers and would have felt the autothrottle moving them to increase power, due to a shortfall in airspeed, which would have also been noticed on the PFD. All normal so far. What was abnormal was the lack of engine response to this movement; not long afterwards this was picked up by the crew and at that point fuel flows became irrelevant.

The differences between the power setting required for the approach and the ones the engines 'hung' at weren't huge. From what I remember it was 1.02 & 1.03EPR with 1.03-1.04EPR/48%N1 needed for F25 and c. 1.06EPR/55%N1 for F30.

Clearly you have not listened or understood what qualified pilots have been repeating ad nauseum. Your continual misinformed posts are an irritation to anybody with a basic understanding of lift/drag ratios.

BOAC, as you bring the subject of Habsheim, the idea that the airplane was limited to prevent it from stalling is part of the myth that’s not even supported by the figures published in the official report.

ALPHA MAX, which is an AoA, was never reached, still 3 degrees off. Therefore the 320 was not limited to prevent it from stalling.
But what we might logically suspect is : Its body attitude may have been limited by an unpublicized protection which would limit the body angle below a specified altitude that could be anywhere below 100 feet RA. Such a protection related to the airplane attitude, could have been designed to merely prevent tailstrike occurrences …

Airbus type Logic ?
 

CONF iture

Now that is a surprise if confirmed

A surprise, perhaps. But why? Tailstrikes can be hideously expensive and dangerous; what would be inconsistent with AB philosophy to protect the a/c from the pilots?

Besides, trees don't grow on runways; what was the a/c doing there in the first place.

MFP. Max flare prot.? MWP Max Whatever Prot? In places this a/c doesn't belong, does it need protection? Or a DM switch. 'Defeat Max __'.

bear

Interesting, CONF - can you expand further? Incidentally, I did not suggest that the AB was being prevented from 'stalling', just that A-prot may have been active. Different thing altogether. Does a-prot limit at a-max - or 3 degrees below............?

Also I would have thought that at 100RA you could practically stand the ***** vertically and not 'strike'?

Anyone else know of this 'unpublicized protection'? TyroP?

AFAIK there was no alpha floor protection under 100ft RA and the only thing the computers had to do with the crash was keeping the wings level as it hit the trees.

Though what this has to do with an undershoot on approach accident like BA038 other than a kneejerk "The machines will kill us all!" response is beyond me... ;)

I see striking similarities. Unavailable (or late) power, Too high AoA, not high enough, Replace the turf with trees, and two a/c hit the deck too early, with a combination of errors both crew and equipment related. One mishap is very strongly crew related, the other equipment derived.

All right, call it stark contrasts, then.

bear

So, the second anniversary, and apart from a lot of very grateful passengers has anything been decided ?

Any ideas on progress on the scientific tests, or another interim report ?

.

Sometimes investigators and manufacturers do not show much enthusiasm in sorting out accidents, just like for the A320 lost in Perpignan a year ago... At least for the BA038 BA managed to give safety medals in a couple of days and showed the airline was above all others (even before knowing what really happened :}).

Please try and show restraint from the modern trend of wanting everything immediately.

The AAIB have never, in my observations, delayed or supressed a report. What I do see when they publish a report is one that is clear, unambiguous in what it says and sticks rigidly to the facts, making recommendations as it sees fit.

It is my understanding that all BA RR powered B777s now have modified fuel/oil heat exchangers fitted and so the apparent dangers appear to have been dealt with according to the known facts so far.

What is the problem apart from impatience on your part?

I agree with your sentiment, however;

"...... It is my understanding that all BA RR powered B777s now have modified fuel/oil heat exchangers fitted and so the apparent dangers appear to have been dealt with according to the known facts so far. ...."

There have been NO findings which deal with the "known facts", merely unrepresentative tests which indicate possible problems, for which the fuel/air heat exchanger mods should be o.k..

If SLFY could actually have bothered to read the thread, he'd have spotted posts 851 and 1005 et seq[1].... :ugh: :rolleyes:

/RTFM

[1]
16th July 2008, 22:55 http://www.pprune.org/4269403-post1534.html
2nd September 2008, 16:53 http://www.pprune.org/4368543-post1692.html

Thanks for the acronym but if you had read the thread carefully you should already have diagnosed your dyslexia...

I think we know how long it usually takes to get a report while most of the time much more data is released during the early stages (in compliance with annex 13). Just like for the Perpignan's A320 it didn't take long for the operator/manufacturer to release it's own conclusions while the investigations seems to be uncertain...

I don't see anything this crew could have done with the power they had available to make the runway. They did a fine job and it worked out pretty well. They might have exceeded AOA but only to not land any shorter than they did. Pilots did a great job with what they had. Hats off to them. Sully into the Hudson is another example of good airmanship. Doesn't mean we couldn't do it but we never had to, thank God.

IMO it cannot be seen any other way. Phil Gollin, the fuel 'mystery' lives, I don't think the FOHE 'fix' solved the 'problem'.

L/D is L/D. "Exceeding AOA" (?) does not increase your gliding distance.

If established at best L/D when they took manual control I agree but the autopilot from what I remember was holding the glide slope so they were well under L/D and a few hundred feet off the ground they would have had to lower the nose and greatly increase their sink rate to regain it. In Sully's case he had the altitude from 3,000 feet to do that. In this case the engine problems happened at 700 ft so they had to be well below 500 ft before they disconnected the AP. I'm sure when this happened is well documented in a few thousand posts back.

Nobody said they should have lowered the nose and reduced the AoA once identified the loss of thrust. Stopping increasing it would already have been great, flying at 118 kts is still better than stalling at 102... (and definitely takes you further).