BA B777 Incident @ Heathrow (merged)
Which Tank in use?
Xeque asked: '....Seriously, at that stage of a long flight, which tanks would be in use? Wing tanks, fuselage tanks or both? ...."
Common practice is to use centre tank fuel (if carried) first, as this reduces bending loads on the wing root and increases the fatigue life, as the wing fuel is evenly distributed in the lifting part of the aircraft, whereas fuselage fuel is not.
Since the investigation into the TWA 800 centre tank explosion (a 747), a quantity of fuel may be carried in the centre tank simply to stabilise the temperature of fuel and minimise fuel vapour, even when centre tank fuel is not required for the flight.
Common practice is to use centre tank fuel (if carried) first, as this reduces bending loads on the wing root and increases the fatigue life, as the wing fuel is evenly distributed in the lifting part of the aircraft, whereas fuselage fuel is not.
Since the investigation into the TWA 800 centre tank explosion (a 747), a quantity of fuel may be carried in the centre tank simply to stabilise the temperature of fuel and minimise fuel vapour, even when centre tank fuel is not required for the flight.
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Prior to descent below 500 agl: "Engines Spooled-Up" ???
Simfly mentioned just above: "... the engines did not "cut out" ... but maybe stayed at the same power setting despite the movements of the power levers..."
That suggests the the B-47 mishaps of the 1950's (that led to the in-flight drag-chute for that clean airplane).
The UA B727 /11nov65 at SLC was the civil exemplar case, led to the published Engine Acceleration Curves in the Boeing _Airliner_ of Jan/Feb '66.
I can also recall one case during Flight Test of the early B767 (some with the early EEC faults), on ground prior to T/O, where pilot advanced the thrust levers, but the engines wouldn't spool-up off Idle RPM [at that point pilots had learnt to cycle the EEC Alternate Action Switch to awaken the FBY Throttles].
That suggests the the B-47 mishaps of the 1950's (that led to the in-flight drag-chute for that clean airplane).
The UA B727 /11nov65 at SLC was the civil exemplar case, led to the published Engine Acceleration Curves in the Boeing _Airliner_ of Jan/Feb '66.
I can also recall one case during Flight Test of the early B767 (some with the early EEC faults), on ground prior to T/O, where pilot advanced the thrust levers, but the engines wouldn't spool-up off Idle RPM [at that point pilots had learnt to cycle the EEC Alternate Action Switch to awaken the FBY Throttles].
In a slightly expanded version of Iloadmyself's response above, in response to Andy_Smith89UK:
It is unlikely that the pilot would lower the undercarriage at such a low altitude (approaching 400ft), unless he was already aware that he had to stretch the glide slope by keeping the aeroplane in a clean configuration, and there is no evidence of that (yet).
As state a couple of posts ago, lowering the undercarriage will greatly increase the drag, and if engine thrust and surplus airspeed are not available to counteract it, the rate of descent will increase.
Non Iron: None taken!
It is unlikely that the pilot would lower the undercarriage at such a low altitude (approaching 400ft), unless he was already aware that he had to stretch the glide slope by keeping the aeroplane in a clean configuration, and there is no evidence of that (yet).
As state a couple of posts ago, lowering the undercarriage will greatly increase the drag, and if engine thrust and surplus airspeed are not available to counteract it, the rate of descent will increase.
Non Iron: None taken!
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First time poster, followed link from Wikipedia.
OK, I have nothing to offer to this already "hot" debate, but I do have one or two things to ask:
1. Why do people complain about speculation on a site which is dedicated to Rumour?
2. What is an SLF, (as I have a feeling I am one)?
3. Why has only one person mentioned lightning?
4. Thank <insert your preferred deity here> that every single soul aboard survived to tell the tale. Is anybody seriously suggesting that to get that plane to "hit" the ground safely as it did was not a(n) heroic feat?
So shoot me.
r011in
OK, I have nothing to offer to this already "hot" debate, but I do have one or two things to ask:
1. Why do people complain about speculation on a site which is dedicated to Rumour?
2. What is an SLF, (as I have a feeling I am one)?
3. Why has only one person mentioned lightning?
4. Thank <insert your preferred deity here> that every single soul aboard survived to tell the tale. Is anybody seriously suggesting that to get that plane to "hit" the ground safely as it did was not a(n) heroic feat?
So shoot me.
r011in
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Gliding down a 767, without both engines from 2 miles away, it is not as easy as it sounds.
Looking back they have done a perfect job.
: a perfect landing of a 767 without both engines, on the grass.
Looking back they have done a perfect job.
: a perfect landing of a 767 without both engines, on the grass.
I'm all for letting non-professionals have a say and ask questions, but if you get the aircraft type wrong after 36 hours of constant news coverage, then you really shouldn't be here!
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Fact or Fiction
Lets leave it to the aviation proffessionals investigating this accident.Praise indeed to the whole proffesionalism of the crew for what could have been a very tragic situation.
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Having flown the aircraft in question (though not recently) I can't help wondering; why does anyone want to second guess the investigation?
A guess, is a guess, is a guess!
A theory, is a theory, is a theory!
Why not leave the speculation to the likes of Learmouth, Moody, and the rest of the sad gutter press.
ANY professional pilot worth his salt, will simply allow the investigation to take it's course!
Anyone who isn't a professional pilot, please feel free to continue your banal commentary on matters you do not comprehend!
A guess, is a guess, is a guess!
A theory, is a theory, is a theory!
Why not leave the speculation to the likes of Learmouth, Moody, and the rest of the sad gutter press.
ANY professional pilot worth his salt, will simply allow the investigation to take it's course!
Anyone who isn't a professional pilot, please feel free to continue your banal commentary on matters you do not comprehend!
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Regarding the engines not responding to autothrottle or crew input, my Boeing QRH for a 737 states that the condition for an "ENGINE LIMIT/SURGE/STALL" is one of more of the following conditions:
* Engine RPM or EGT indications are abnormal, approaching or exceeding limits
* No response to thrust lever movement
* Abnormal engine noises.
So in this case, I would classify this as both engines stalling at the same time. Of course the 777 checklist may contain different criteria for engine stall...
Edit: the non-customized 777 checklist contains the same, plus an 'unusual indications condition'.
* Engine RPM or EGT indications are abnormal, approaching or exceeding limits
* No response to thrust lever movement
* Abnormal engine noises.
So in this case, I would classify this as both engines stalling at the same time. Of course the 777 checklist may contain different criteria for engine stall...
Edit: the non-customized 777 checklist contains the same, plus an 'unusual indications condition'.
Last edited by DraggieDriver; 19th Jan 2008 at 01:22.
Fly Conventional Gear
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Don't some autothrottles have a tendency to 'overreact' sometimes to events like loss/gain of airspeed?...perhaps in the gusty conditions at the time the autothrottles had just retarded almost to idle after a large gain in airspeed and then failed to power up again? Presuming they were flying a normal stable approach until 600ft the power setting they would presumably have had (even if the engines did get 'stuck' at that setting) would have been enough to carry the plane a bit further than it actually went. Possible combo of windshear and unresponsive engines?
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Interesting news report with a Dutch pax suggesting he did not know he had just CRASH LANDED..
http://video.google.com.au/videoplay...30773432754019
http://video.google.com.au/videoplay...30773432754019
Many, many years go, when I was a young pilot, there was an incident in where I live, with Airbus A300's. Company was Karair, at that time a charter subsidiary of Finnair, they had two A300's, with highest utilisation of the type then, basically flying non-stop between Finland and the Canary Islands. About 18 hours airborne per day per aircraft, if I recall correctly. At some point, it was discovered that there was a huge chunk of ice floating in the fuel tank of one of the aircraft, as the condenced water never had time to melt, and thus had never been drained from the system between the flights. The aircraft had actually been very close to fuel starvation because of this. Of course, about 20 years have passed, lessons have been learnt, and this could not happen again, couldn't it...?
I think about 10 years ago Continental had an issue with their early 777s in that during winter ops from NWK the fuel temp never dropped sufficiently to allow any suspended/solid water to thaw and therefore be drained during normal routine checks. Result was a very large, thick sheet of ice in the base of the fuel tanks which would often give erroneous tank qty readings.
I have no idea if this has anything to do with recent events. I just wanted to comment on the above quote.
BTW. I heard Danny on BBC R2 today. Excellent. Kept to the facts as known and refrained from speculation. However, as soon as Danny had signed off the R2 DJ, Jeremy Vine, then asked the listeners to "ring in with tales of any near miss experiences they had".
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If you compare a pilot to a surgeon, there are certain similarities: they both perform a very technical task, sometimes over long hours, and if they cock it up, people die. I wonder if surgeons go on medical forums, and moan at GPs or patients for discussing medical procedures? "You're not a cardiac surgeon, so stop speculating about failed pacemakers!"
2) Self-Loading Freight. The implication is that airline passengers are dead weight, and should not be seen or heard from. As an insult, it's not working, so you'll see it used by passengers in a way Alanis Morissette would appreciate.
3) I thought two had mentioned it?
My SLF opinion is on that is somewhere between a) probably not, it would surely have been noticed, or b) could have had an effect on other components, but premature to speculate e.g. a lot of talk in this thread about possible FADEC problems, but it's not been reported that there were any such problems, so it's pointless to worry about an indirect cause like lightning at this early stage in investigation. 4) Deities have sod-all to do with it: thank the pilots, and Boeing engineers.
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contactower makes a good point.
it would seem that at 600feet the crew tried to get more power...and it didn't happen.
if they had tried at 1500 feet there would have been more time to react, including a BRACE call/signal to the cabin.
it would seem that at 600feet the crew tried to get more power...and it didn't happen.
if they had tried at 1500 feet there would have been more time to react, including a BRACE call/signal to the cabin.
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Reading some of the posts regarding this awful incident which I hope never happens to me in my flying career, respect that the crew are in massive shock at this stage. They did a great job!
Nobody has an idea what happened apart from the crew, AAIB and flight safety in BA.
Nobody has an idea what happened apart from the crew, AAIB and flight safety in BA.
Possibly misguided theory
As I noted in my last post, I'm not a pilot, so feel free to take this with a grain of salt...
IMHO, the evidence doesn't seem to point to any sort of fuel or other engine problem. For both engines to stop responding to throttle input sounds much more like a problem somewhere in the FBW path.
So here's my theory/question... If the computer thinks that the a/c is in an overspeed situation, would advancing the throttles be "ignored"? I haven't heard anything about alarms (such as overspeed) in the cockpit, but what would happen if somewhere in the electronics, an overspeed sensor/algorithm malfunctioned? Is it possible that this would interrupt the throttle commands from both a/t and manually advancing the levers?
IMHO, the evidence doesn't seem to point to any sort of fuel or other engine problem. For both engines to stop responding to throttle input sounds much more like a problem somewhere in the FBW path.
So here's my theory/question... If the computer thinks that the a/c is in an overspeed situation, would advancing the throttles be "ignored"? I haven't heard anything about alarms (such as overspeed) in the cockpit, but what would happen if somewhere in the electronics, an overspeed sensor/algorithm malfunctioned? Is it possible that this would interrupt the throttle commands from both a/t and manually advancing the levers?
Ice?
Certain types of engine icing might lead to an unresponsive engine, and this could affect both simultaneously; or with decreased efficiency on one, the other engine struggles which might make it more susceptible to the effects of ice, so shortly after both are affected.
Although most engines are anti-iced, some of the big fans rely on fan-ice shedding (centrifugal action) at higher rpm. Thus during an approach with relatively lower rpm and in unusual conditions of a lengthy exposure to the ‘exact’ icing conditions (and possibly without engine anti icing) problems might be encountered.
IIRC the smaller fan F100 and 146 engines suffered fan icing in freezing conditions when taxiing – low engine speed. Some aircraft types also suffered from this in-flight (exceptional atmospheric conditions) where the situation was usually indicated with a Vib warning and cleared with an increase of thrust (within the temp limits).
Ice can affect the efficiency of the engine (mainly fan thrust); autothrust seeks to adjust thrust to maintain desired airspeed, the engine is reluctant to respond / insufficient thrust (due to the effect of ice), more thrust lever input, mismatch in fuel/air/engine speed ratios; - bad situation turning worse.
At what engine speed does a Gen come off line during an in-flight shutdown (normal shutdown – ice free windmill characteristics) or in a sub idle condition?
Although most engines are anti-iced, some of the big fans rely on fan-ice shedding (centrifugal action) at higher rpm. Thus during an approach with relatively lower rpm and in unusual conditions of a lengthy exposure to the ‘exact’ icing conditions (and possibly without engine anti icing) problems might be encountered.
IIRC the smaller fan F100 and 146 engines suffered fan icing in freezing conditions when taxiing – low engine speed. Some aircraft types also suffered from this in-flight (exceptional atmospheric conditions) where the situation was usually indicated with a Vib warning and cleared with an increase of thrust (within the temp limits).
Ice can affect the efficiency of the engine (mainly fan thrust); autothrust seeks to adjust thrust to maintain desired airspeed, the engine is reluctant to respond / insufficient thrust (due to the effect of ice), more thrust lever input, mismatch in fuel/air/engine speed ratios; - bad situation turning worse.
At what engine speed does a Gen come off line during an in-flight shutdown (normal shutdown – ice free windmill characteristics) or in a sub idle condition?