BA038 (B777) Thread
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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.
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.
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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...
the experiment related in the posted comment is biased for two reasons:
- Attempting to stretch the glide won’t be obtained by bringing the speed towards stall speed, but by keeping the speed.
- Both engines were not failed but still producing some minimal thrust above flight idle.
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?
... no judgement here on the BA38 crew actions, but I disagree with the main idea you push forward in the thread.
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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
Who thinks slowing by from 118 kts Flaps 25 that they're INCREASING their gliding distance by slowing to 108 kts Flaps 25??? 
You're going from (approx.) Vref -20 to Vref -30. That's going to INCREASE your performance???
So, if you're on the back side of the power curve(lift curve/drag curve, whatever you want to call it in pilot terms) and slowing an additional 10 kts will INCREASE your gliding performance?
You're going from (approx.) Vref -20 to Vref -30. That's going to INCREASE your performance???So, if you're on the back side of the power curve(lift curve/drag curve, whatever you want to call it in pilot terms) and slowing an additional 10 kts will INCREASE your gliding performance?
Another issue is that by slowing to AOA limits there is no excess energy(ie airspeed) to try and flare. That woud allow for a slightly decreased sink rate at impact.
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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).
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.
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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 
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It was not sufficient to prevent the partial destruction of the aircraft. By any definition, that is a crash. (And happens to be a crash by the official definition, too.)
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.
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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.
-----------------------------------------------------------------------
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.
Last edited by misd-agin; 11th Jan 2010 at 03:42. Reason: clarification
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The arguement is 135 kts Flaps 30 gliding performance better than 118 kts Flaps 25?
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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.
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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
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
Last edited by Bis47; 12th Jan 2010 at 12:26.
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Originally Posted by woodpecker
it was one of those days) you are struggling to maintain (even with today's autothrottle systems) plus or minus 5kts on the bugged speed (at best).
Controversial, moi?
..unfortunately i fly nothing real, just the ms sim + good share of SLF
In that kind of weather, some margin about(sic) normal Vref should be applied, isn't it?
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) ?
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) ?
Controversial, moi?
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.
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.
Mistrust in Management
Bis47
In that kind of weather, some margin about normal Vref should be applied, isn't it?
Regards
Exeng
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Alleluiah !!!
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.
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.
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.
Not recognizing soon enough that an exceptional problem justifies throwing out all SOPs ... and applying instead basic airmanship, basic flying skills : this is what the story is all about (regarding crew actions, and regarding company training as well).
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?
Remember, the engines were still running and there were no warnings, messages or alerts.
Last edited by Smilin_Ed; 11th Jan 2010 at 18:58. Reason: Clarity
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Originally Posted by exeng
The A320/319 (and other buses I believe) use a feature called 'ground speed mini' which could be quite startling in very strong winds!
Would be really curious to simulate and analyse a similar scenario in a 340 …
Report says FF were at 5 and 6000 pph ...