BA038 (B777) Thread
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nhs, please look at the post mentioned above and others in the same page.
Please understand that I agree 100% with the what M.Mouse, a Pilot, says: it would have been superhumane to land succesfully in these conditions, in other words even if it would have been theoretically possible, nobody can expect an unprepared crew to accomplish.
Anyway for the last time, if anyone wants to believe that it was a manual landing, OK with me, but it was not.
Please understand that I agree 100% with the what M.Mouse, a Pilot, says: it would have been superhumane to land succesfully in these conditions, in other words even if it would have been theoretically possible, nobody can expect an unprepared crew to accomplish.
Anyway for the last time, if anyone wants to believe that it was a manual landing, OK with me, but it was not.
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I have read the latest AAIB report.
Water content of the fuel seems to have been established from fuel samples after the crash.
According to the AAIB and other reports, most of the remaining fuel was spilled and only a few tons remained.
Somebody, many hundreds of posts ago, suggested that, with water being heavier than fuel, under the circumstances a lot of water could already have drained from the aircraft by the time the fuel samples were taken.
Question: might there have been a lot more water than quoted in the AAIB report?
CJ
Water content of the fuel seems to have been established from fuel samples after the crash.
According to the AAIB and other reports, most of the remaining fuel was spilled and only a few tons remained.
Somebody, many hundreds of posts ago, suggested that, with water being heavier than fuel, under the circumstances a lot of water could already have drained from the aircraft by the time the fuel samples were taken.
Question: might there have been a lot more water than quoted in the AAIB report?
CJ
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At last ... some official indications on crew actions ...
28 sec before impact thrust levers were partially cycled
16 sec before impact flaps were raised from 30 to 25 (you was correct M.Mouse !)
8 sec before impact FO pushed the control column
At that time AP disconnected, pitch attitude was 14 deg up, anyone to determine the AOA ?
Flight idle fuel flow looks to be around 3000 pph per engine ... surprised that 6 and 5000 pph did not bring the aircraft a bit further ?
Note: Right FF maintained pretty stable at 6000 pph when Left FF reduced from 5 to 4000 pph in the last 15 sec
28 sec before impact thrust levers were partially cycled
16 sec before impact flaps were raised from 30 to 25 (you was correct M.Mouse !)
8 sec before impact FO pushed the control column
At that time AP disconnected, pitch attitude was 14 deg up, anyone to determine the AOA ?
Flight idle fuel flow looks to be around 3000 pph per engine ... surprised that 6 and 5000 pph did not bring the aircraft a bit further ?
Note: Right FF maintained pretty stable at 6000 pph when Left FF reduced from 5 to 4000 pph in the last 15 sec
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Boeing is releasing new operating procedures to deal with the BA038 icing threat, according to this newspiece in FlightGlobal.
Interestingly, they seem to concentrate on the "ice blocking heat exchanger" scenario and not the "ice accretion in the pipes" scenario.
Interestingly, they seem to concentrate on the "ice blocking heat exchanger" scenario and not the "ice accretion in the pipes" scenario.
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Glue Ball,
Increasing AOA to stay on the glide until the stick shaker is activated ( what the autopilot did according to the AAIB report ) is definitely not the way to get the best chance of making it to the runway... It is a fact, simple fly mechanics. Stall speed is certainly not the best gliding speed.
Therefore, considering that the plane missed the runway by a reasonably short distance, it is not a surprise that a pilot WHO KNOWS WHAT IS GOING TO HAPPEN, i.e. that the thrust will never come back, could be able to land the plane on the concrete by immediately taking the right speed, slope, and wing configuration. So, i am pretty confident that the simulation may be quite relevant.
That doesn't mean that the real pilots on the real flight were wrong in their actions, they had no way to guess what was to happen in the next seconds...
And in fact, they saved the day by pushing the stick and reducing flaps as soon as the situation became clear.
Increasing AOA to stay on the glide until the stick shaker is activated ( what the autopilot did according to the AAIB report ) is definitely not the way to get the best chance of making it to the runway... It is a fact, simple fly mechanics. Stall speed is certainly not the best gliding speed.
Therefore, considering that the plane missed the runway by a reasonably short distance, it is not a surprise that a pilot WHO KNOWS WHAT IS GOING TO HAPPEN, i.e. that the thrust will never come back, could be able to land the plane on the concrete by immediately taking the right speed, slope, and wing configuration. So, i am pretty confident that the simulation may be quite relevant.
That doesn't mean that the real pilots on the real flight were wrong in their actions, they had no way to guess what was to happen in the next seconds...
And in fact, they saved the day by pushing the stick and reducing flaps as soon as the situation became clear.
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Thanks M.Mouse (#1780)
Re: my question 1778 http://www.pprune.org/rumours-news/3...ml#post4375609, your answer 1780 http://www.pprune.org/rumours-news/3...ml#post4375780, linking to http://www.pprune.org/rumours-news/3...ml#post4322326
Indeed it does answer my question, M.Mouse. Thanks.
I didn't think of exploiting ground effect to boost lift: the picture of a glider/skydiver landing didn't jump into my mind when imagining their 777 over Hounslow.
If I may ask, how did it work out for you on the `several attempts' prior to using the recipe you posted on the `medal' thread for reaching the threshold in the simulator?
Indeed it does answer my question, M.Mouse. Thanks.
I didn't think of exploiting ground effect to boost lift: the picture of a glider/skydiver landing didn't jump into my mind when imagining their 777 over Hounslow.
If I may ask, how did it work out for you on the `several attempts' prior to using the recipe you posted on the `medal' thread for reaching the threshold in the simulator?
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Hi all,
in the report iy says there are three tanks on 777.
Im a 340/330 guy and just wondering if there ain't any outboard tanks inside the wing tanks.
In the 340/330 there is an outboard tank which usually has around 2500 kg of fuel. This fuel is kept near the edge of the wing to help reduce the moment of lift at the wings. The coldest fuel is most of the time in this tank and this tank usually will be used at the end of the flight when all other fuel is used.
My questions for the 777 experts:
1) Is there a small tank like this at the edge of the wing ?
If yes
2) is there a fuel temperature sensor for this tank on the 777 ?
Regards,
Guclu
in the report iy says there are three tanks on 777.
Im a 340/330 guy and just wondering if there ain't any outboard tanks inside the wing tanks.
In the 340/330 there is an outboard tank which usually has around 2500 kg of fuel. This fuel is kept near the edge of the wing to help reduce the moment of lift at the wings. The coldest fuel is most of the time in this tank and this tank usually will be used at the end of the flight when all other fuel is used.
My questions for the 777 experts:
1) Is there a small tank like this at the edge of the wing ?
If yes
2) is there a fuel temperature sensor for this tank on the 777 ?
Regards,
Guclu
Respect...
An impressive AAIB report which I am sure will reward more study.
For those unhappy that an extremely unlikely event should affect two independent systems within a few seconds of one another - there is a common factor over and above the shared history of those systems. The centre tank which is supposed to be empty, but is still in the loop.
The previous flight is significant because with ground temperatures in Beijing below zero, any ice from the outbound flight would not be scavenged.
The fuel uploaded in Beijing was warm enough to have melted this into droplets; the behaviour of the resulting droplets in terms of their size, accretion rate and so on, in the centre tank of an aircraft at rest in a below zero environment is problematic, but if it froze again before start-up, the water scavenge, and later the fuel scavenge would not get it. It would not start to melt and move from the 'empty' centre tank until the warmer environment of the descent.
So there is the credible possibility that at some time in the descent a melt surge presents ice, wateer and/or slush at the centre tank fuel scavenge points, and is then fed to the main tanks to be refrozen as it makes its way down to the boost pumps .....
If this happens during an unusually prompt arrival at late finals on a cold winters day, another hole lines up.
It would be particularly concerning if a procedural attitude or acceleration change could trigger such an episode which then prompts a temporary fuel restriction episode timed to coincide with a critical procedural need for more power.
Since the AAIB work is continuing, they must believe further recommendations are a possibility.
For those unhappy that an extremely unlikely event should affect two independent systems within a few seconds of one another - there is a common factor over and above the shared history of those systems. The centre tank which is supposed to be empty, but is still in the loop.
The previous flight is significant because with ground temperatures in Beijing below zero, any ice from the outbound flight would not be scavenged.
The fuel uploaded in Beijing was warm enough to have melted this into droplets; the behaviour of the resulting droplets in terms of their size, accretion rate and so on, in the centre tank of an aircraft at rest in a below zero environment is problematic, but if it froze again before start-up, the water scavenge, and later the fuel scavenge would not get it. It would not start to melt and move from the 'empty' centre tank until the warmer environment of the descent.
So there is the credible possibility that at some time in the descent a melt surge presents ice, wateer and/or slush at the centre tank fuel scavenge points, and is then fed to the main tanks to be refrozen as it makes its way down to the boost pumps .....
If this happens during an unusually prompt arrival at late finals on a cold winters day, another hole lines up.
It would be particularly concerning if a procedural attitude or acceleration change could trigger such an episode which then prompts a temporary fuel restriction episode timed to coincide with a critical procedural need for more power.
Since the AAIB work is continuing, they must believe further recommendations are a possibility.
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Snowfalcon2
I think the idea is that the ice forms in the pipes and collects on the face of the heat exchanger. The procedures attempt to dislodge the ice before enough builds up to cause a problem. I can see the need to do the powerback and wait(hope) shortly after the pre descent power up!!
Hotel Mode,
Never seen it - guess I stopped flying before you started. Last time I asked Boeing they couldn't help.
Dont think thats new, its been in the manuals for as long as i can remember.
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Barit 1 said:
I agree with Barit1 here,
The solution to an Hi temp light coming on in the decent (which is not uncommon) for many twin-spooled engines is to push up the power and throw out the boards, because those are fuel-cooled oil systems: the increased fuel flow (higher than idle) cools the oil system and the light goes out. No need to write it up since you just fixed the problem.
The point here being: decent at idle is a high-temp situation; not a freezing situation. I know that sounds backwards, but for most of the seven transport types I flew that is true.
However, the heat exchanger is no doubt regulated by another computer chip on this tripple spooled model. More complexity equals more unreproducible, unpredictable results.
This accident already is shaping up to be another 737-Rudder, 747-center-fuel-tank mystery.
Blaming icing by itself seems unlikely to me. The 747SP flew up to 45,000 feet for 26 hours routinely for thirty years and never had any problems (that I know of.) It even completed a 54 hour flight. KC-135's B-52's and airborne command posts have remained aloft for days without any problems.
Tanimbar said:
I agree Tanibar and others, this is a shocking statement and makes me wonder how other airframes have stayed aloft for over a quarter of a century with no icing problems. Prist type additives? The 747SP (which I merely jumpseated) has nine tanks and surely runs into this problem up in the 40's. But all of the aircraft I mentioned (747SP, B-52, KC-135, 747-EAC-1) were non-FADEC (before engine upgrades) and their safety records were based on direct-link hydro-mechanical designs.
The FADEC is usually the culprit when you are discussing rollbacks. A pilot with a control cable would keep trying to clear the ice out by trial and error. A FADEC goes back to idle and tries to reboot a start sequence.
JMHO's only.
I'm not sure this adds up. The "amazingly efficient" Trent with more spools, and more bearings, probably has more heat generated in the oil, and thus any "stagnating" fuel will be exposed to more BTU transfer, leading to LESS probability of icing in the fuel-oil heat exchanger.
Often the most severe design point for the cooler is early in descent, when lube heat rejection is still high, yet fuel flow (the heat sink) is very low.
Often the most severe design point for the cooler is early in descent, when lube heat rejection is still high, yet fuel flow (the heat sink) is very low.
I agree with Barit1 here,
The solution to an Hi temp light coming on in the decent (which is not uncommon) for many twin-spooled engines is to push up the power and throw out the boards, because those are fuel-cooled oil systems: the increased fuel flow (higher than idle) cools the oil system and the light goes out. No need to write it up since you just fixed the problem.
The point here being: decent at idle is a high-temp situation; not a freezing situation. I know that sounds backwards, but for most of the seven transport types I flew that is true.
However, the heat exchanger is no doubt regulated by another computer chip on this tripple spooled model. More complexity equals more unreproducible, unpredictable results.
This accident already is shaping up to be another 737-Rudder, 747-center-fuel-tank mystery.
Blaming icing by itself seems unlikely to me. The 747SP flew up to 45,000 feet for 26 hours routinely for thirty years and never had any problems (that I know of.) It even completed a 54 hour flight. KC-135's B-52's and airborne command posts have remained aloft for days without any problems.
Tanimbar said:
On another matter. The AAIB interim report states (Water ice in fuel, p12),
Quote:
As the fuel temperature is further reduced, it reaches the Critical Icing Temperature, which is the temperature at which the ice crystals will start to stick to their surroundings. When the fuel temperature reduces to approximately ‑18°C (0°F), the ice crystals adhere to each other and become larger. Below this temperature little is known about the properties of ice crystals in fuel and further research may be required to enable the aviation industry to more fully understand this behaviour.
I read this with disbelief. The words, "little is known" is, well, shocking.
Until today I had thought that the industry had fully experimented, tested and evaluated the effects of temperature on fuel (at all operating ranges).
By the way, my money is still on stratification ( no, don't respond to this; I need to read the report more carefully and may change my mind).
Regards, Tanimbar
Quote:
As the fuel temperature is further reduced, it reaches the Critical Icing Temperature, which is the temperature at which the ice crystals will start to stick to their surroundings. When the fuel temperature reduces to approximately ‑18°C (0°F), the ice crystals adhere to each other and become larger. Below this temperature little is known about the properties of ice crystals in fuel and further research may be required to enable the aviation industry to more fully understand this behaviour.
I read this with disbelief. The words, "little is known" is, well, shocking.
Until today I had thought that the industry had fully experimented, tested and evaluated the effects of temperature on fuel (at all operating ranges).
By the way, my money is still on stratification ( no, don't respond to this; I need to read the report more carefully and may change my mind).
Regards, Tanimbar
I agree Tanibar and others, this is a shocking statement and makes me wonder how other airframes have stayed aloft for over a quarter of a century with no icing problems. Prist type additives? The 747SP (which I merely jumpseated) has nine tanks and surely runs into this problem up in the 40's. But all of the aircraft I mentioned (747SP, B-52, KC-135, 747-EAC-1) were non-FADEC (before engine upgrades) and their safety records were based on direct-link hydro-mechanical designs.
The FADEC is usually the culprit when you are discussing rollbacks. A pilot with a control cable would keep trying to clear the ice out by trial and error. A FADEC goes back to idle and tries to reboot a start sequence.
JMHO's only.
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I was happy to see the cavitation marks mystery solved. 
I suppose this blows the electronic/computer glitch theories out of the water finally.
From http://www.pprune.org/3852203-post176.html posted by a handsome fellow I know well.
I suppose this blows the electronic/computer glitch theories out of the water finally.
The idea that a computer or power failure could shutdown both engines
might be possible on some aircraft, but not this one.
might be possible on some aircraft, but not this one.
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Interesting report. It's mentioning twice that the CVR worked and nothing much. I'm glad it worked but I guess it could be even more interesting to have some details about its content.
According to the FDR the captain retracted the flaps to 25 at 240 ft resulting in increasing the pitch up attitude while the AP was already pulling on the nose to follow the glide until reaching 14 degres nose up. The AP finaly disconected following the stick shaker when the FO pushed on the stick at 170 ft and around 100 kts.
Usualy retracting flaps in dead stik approach is associated to a nose down command and speed increase, not the contrary.
According to the FDR the captain retracted the flaps to 25 at 240 ft resulting in increasing the pitch up attitude while the AP was already pulling on the nose to follow the glide until reaching 14 degres nose up. The AP finaly disconected following the stick shaker when the FO pushed on the stick at 170 ft and around 100 kts.
Usualy retracting flaps in dead stik approach is associated to a nose down command and speed increase, not the contrary.
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Differences between Trent 800 and GE90
One of the reasons that interim procedures published by Boeing apply only to Trent 800 powered 777s could be differences in design between the two engines. (See Boeing 777 FCOM)
Fuel System, Flow Path:
Trent 800:
1st Stage Engine Driven Fuel Pump
Fuel/Oil Heat Exchanger (FOHE)
Fuel Filter
2nd Stage Engine Driven Fuel Pump
Fuel Metering Unit (FMU)
GE90
1st Stage Engine Driven Fuel Pump
2nd Stage Engine Driven Fuel Pump
FOHE
Fuel Filter
FMU
This means that on GE90 engines the fuel has already gone through the second stage (HP) fuel pump before it enters the FOHE, which will cause some rise in temperature
Oil System, Flow Path:
Trent 800:
Oil Pump
HP Oil Filter
Air/Oil Heat Exchanger
FOHE
GE90:
Oil Pump
HP Oil Filter
FOHE
Backup Gen Oil/Oil Heat Exchanger
That means that in Trents the oil has already part of the heat extracted in the air/oil heat exchanger before it makes its way into the FOHE.
No conspiracy theory required after all?
Fuel System, Flow Path:
Trent 800:
1st Stage Engine Driven Fuel Pump
Fuel/Oil Heat Exchanger (FOHE)
Fuel Filter
2nd Stage Engine Driven Fuel Pump
Fuel Metering Unit (FMU)
GE90
1st Stage Engine Driven Fuel Pump
2nd Stage Engine Driven Fuel Pump
FOHE
Fuel Filter
FMU
This means that on GE90 engines the fuel has already gone through the second stage (HP) fuel pump before it enters the FOHE, which will cause some rise in temperature
Oil System, Flow Path:
Trent 800:
Oil Pump
HP Oil Filter
Air/Oil Heat Exchanger
FOHE
GE90:
Oil Pump
HP Oil Filter
FOHE
Backup Gen Oil/Oil Heat Exchanger
That means that in Trents the oil has already part of the heat extracted in the air/oil heat exchanger before it makes its way into the FOHE.
No conspiracy theory required after all?
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is the 5th report, and still the reason od that reduced fuel flow is unclear.
interesting report anyway but:
1) I was surprised to read that such approach was conducted in Autopilot. It would seams that they had other problems to handle if they decided to perform an auto land.
2) I was surprise by the action (desperate i believe) of the commander reducing the flap setting and continuing to keep the plane in autopilot,
3) I was surprise that the crew failed to anticipate the stick shaker situation (they do not have an Alpha floor protection)
4) I was surprise that the A/P was disconnected only by the F/O that apparently pushed the column into the Eicas (as supposed to do)
since the only possible obstruction was up stream of the HP pump It looks like the B777 needs like a Cessna a hot hair (to the carburator) swith, or some Aspirine in the tanks to reduce the piping cholesterol of this giant plane.
interesting report anyway but:
1) I was surprised to read that such approach was conducted in Autopilot. It would seams that they had other problems to handle if they decided to perform an auto land.
2) I was surprise by the action (desperate i believe) of the commander reducing the flap setting and continuing to keep the plane in autopilot,
3) I was surprise that the crew failed to anticipate the stick shaker situation (they do not have an Alpha floor protection)
4) I was surprise that the A/P was disconnected only by the F/O that apparently pushed the column into the Eicas (as supposed to do)
since the only possible obstruction was up stream of the HP pump It looks like the B777 needs like a Cessna a hot hair (to the carburator) swith, or some Aspirine in the tanks to reduce the piping cholesterol of this giant plane.
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ZAGORFLY
1. They were not performing an "autoland". They were performing an autocoupled approach to disconnect at some point prior to a manual landing. Like probably 99%+ of airline approaches...
2. The Final Flap setting (30 for 777, Full for Airbus etc.) is largely all drag... You describe it as desparate... most would describe it as inspried and almost certainly saved many lives. Training nowadays is almost 100% directed towards using the AP with a problem - not disconnecting it.
3. They did not "fail to anticipate" the stick shaker... they had already selected full thrust many seconds before
4. I doubt the SFO "pushed the CC into the EICAS" - nor do I think that is the laid down drill in the QRH/FM
IMHO you and many others are wasting your time dissecting what the crew did (or did not do). They did a damn good job, working outside the box, but not excessively so, whilst trying to correctly troubleshoot the problem(s). Assuming you are even a pilot (?) since when do you practice stall recoveries close to the ground AND with zero power... it is not taught in anything (other than a glider?) since it is negative, improbable and inapproriate.
We do train for engine failures, and we do train for stall recoveries (but with power, or at least height).
This inquiry, IMHO, is 99% concentrating on WHAT caused the power failure(s), and preventing future occurances... in the short term by determining the circumstances and avoiding then, and in the longer term by design. I think it unlikely more than a fraction of the final report, and probably none of the formal recommendations, will be on crew actions / extra training to deal with essentially a double engine failure at ~2NM
NoD
1) I was surprised to read that such approach was conducted in Autopilot. It would seams that they had other problems to handle if they decided to perform an auto land.
2) I was surprise by the action (desperate i believe) of the commander reducing the flap setting and continuing to keep the plane in autopilot,
3) I was surprise that the crew failed to anticipate the stick shaker situation (they do not have an Alpha floor protection)
4) I was surprise that the A/P was disconnected only by the F/O that apparently pushed the column into the Eicas (as supposed to do)
2) I was surprise by the action (desperate i believe) of the commander reducing the flap setting and continuing to keep the plane in autopilot,
3) I was surprise that the crew failed to anticipate the stick shaker situation (they do not have an Alpha floor protection)
4) I was surprise that the A/P was disconnected only by the F/O that apparently pushed the column into the Eicas (as supposed to do)
2. The Final Flap setting (30 for 777, Full for Airbus etc.) is largely all drag... You describe it as desparate... most would describe it as inspried and almost certainly saved many lives. Training nowadays is almost 100% directed towards using the AP with a problem - not disconnecting it.
3. They did not "fail to anticipate" the stick shaker... they had already selected full thrust many seconds before
4. I doubt the SFO "pushed the CC into the EICAS" - nor do I think that is the laid down drill in the QRH/FM
IMHO you and many others are wasting your time dissecting what the crew did (or did not do). They did a damn good job, working outside the box, but not excessively so, whilst trying to correctly troubleshoot the problem(s). Assuming you are even a pilot (?) since when do you practice stall recoveries close to the ground AND with zero power... it is not taught in anything (other than a glider?) since it is negative, improbable and inapproriate.
We do train for engine failures, and we do train for stall recoveries (but with power, or at least height).
This inquiry, IMHO, is 99% concentrating on WHAT caused the power failure(s), and preventing future occurances... in the short term by determining the circumstances and avoiding then, and in the longer term by design. I think it unlikely more than a fraction of the final report, and probably none of the formal recommendations, will be on crew actions / extra training to deal with essentially a double engine failure at ~2NM
NoD
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Ice Ice Baby
Captain Big Iron:
Also Concorde comes to mind. I know that the Investigation team is of the very best and the report is extremely thorough. But still, after millions of flights by both 747 and 777 aircraft on these routes in similar conditions, it does seen strange. I suppose that on this particular flight the holes in the Swiss cheese slices just happened to align perfectly?
There have been several other reports of 777 aircraft having engines not respond to commands in situations where ice is not likely to have been an issue. To those familiar with the 777, did these incidents also involve RR Trents and have these incidents been adequately explained?
Blaming icing by itself seems unlikely to me. The 747SP flew up to 45,000 feet for 26 hours routinely for thirty years and never had any problems (that I know of.) It even completed a 54 hour flight. KC-135's B-52's and airborne command posts have remained aloft for days without any problems.
There have been several other reports of 777 aircraft having engines not respond to commands in situations where ice is not likely to have been an issue. To those familiar with the 777, did these incidents also involve RR Trents and have these incidents been adequately explained?
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Fuel Heating
I am surprised this has not been more in the forefront of thoughts. I cannot say specifically for the B747SP, but certainly for the "classic" B747 and going back a few more years, the B707, they had dedicated fuel heaters. these were switched on by the flight engineer if he had a Fuel Filter Block warning light. After a set period of time, the fuel heater was switched off.
Looking at the diagrams on this thread, fuel heating is only supplied by the Fuel/Oil heat exchanger.
Just a thought ....
Looking at the diagrams on this thread, fuel heating is only supplied by the Fuel/Oil heat exchanger.
Just a thought ....
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Last 720 ft
Just my 2C,
If the AAIB are prepared to go public on a very probable icing issue here, after my 15,00hrs, much of it Ultra Long Haul, albeit on B747s, I will believe them.
The crew actions can be second guessed forever, but after the Schipol freighter double engine failure and loss a few years ago, we tried it (As I'm sure most 747 operators in the world did) in the sim.
Being fully aware of the preliminary reports, doing a briefing, and configuring the sim as best we could to simulate the conditions experienced by the crew, it took me, as a Training Captain, 4 tries to achieve even a marginally survivable result----and this was not at the end of a 15 hour day.
Re a previous post, from my recall, the 747 at F25 required an increase of pitch of about 1.25 degrees above that for F30, but with a significant decrease in power required i.e. drag, so good call there for the flap reduction.
Well done crew.
As an aside, from the later pictures, it would appear that a significant part of the A/C was on the piano keys, so it wasn't really a short landing, just an early touchdown.
I'll get my coat.
If the AAIB are prepared to go public on a very probable icing issue here, after my 15,00hrs, much of it Ultra Long Haul, albeit on B747s, I will believe them.
The crew actions can be second guessed forever, but after the Schipol freighter double engine failure and loss a few years ago, we tried it (As I'm sure most 747 operators in the world did) in the sim.
Being fully aware of the preliminary reports, doing a briefing, and configuring the sim as best we could to simulate the conditions experienced by the crew, it took me, as a Training Captain, 4 tries to achieve even a marginally survivable result----and this was not at the end of a 15 hour day.
Re a previous post, from my recall, the 747 at F25 required an increase of pitch of about 1.25 degrees above that for F30, but with a significant decrease in power required i.e. drag, so good call there for the flap reduction.
Well done crew.
As an aside, from the later pictures, it would appear that a significant part of the A/C was on the piano keys, so it wasn't really a short landing, just an early touchdown.
I'll get my coat.
Join Date: Feb 2000
Location: asia
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Question from a non pilot.
When a liquid is compressed, temperature rises. When pressure reduced, temperature falls.
How is the flow of fuel controlled (physically, not logically) ?
Would it be possible for the 'valve' controlling the flow to form a point at which pressure was reduced, thus cooling the fuel even more and maybe causing ice to aggregate?
A small restriction could then, under some circumstances, become self perpetuating
When a liquid is compressed, temperature rises. When pressure reduced, temperature falls.
How is the flow of fuel controlled (physically, not logically) ?
Would it be possible for the 'valve' controlling the flow to form a point at which pressure was reduced, thus cooling the fuel even more and maybe causing ice to aggregate?
A small restriction could then, under some circumstances, become self perpetuating