Did a BA B747 dump 50t of fuel due to a miscalculation?
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Having been involved with de-fuelling over the years I can confirm that it was indeed a pain in the backside taking fuel off an aircraft.
Fuel being taken off an aircraft does NOT go back to the depot, it is put on another company aircraft, subject to contamination checks etc. If it fails them it goes for central heating oil.
Fuel being taken off an aircraft does NOT go back to the depot, it is put on another company aircraft, subject to contamination checks etc. If it fails them it goes for central heating oil.
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Lots of people saying that the processes in place wouldn't allow this to happen etc etc. I've been on a flight where all three of the crew failed to notice that we were 5T over our MLW on a AUH - SEZ sector. Blamed it on the Flt Eng!!!
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Old not Bold
Its quite common to have that restriction on re-use defuelling.
Aircraft fuel is subject to a chain of custody type arrangement and is incredibly well tested, inspected and certified, even though each batch is slightly different because of small variations in its distillation charateristics, the refinery it came from and the processes employed there (eg in catlytic cracking, Sulphur removal etc.), and the crude it was distilled from. Even the minute amounts of water and sediment it picked up during distribution is removed just before final storage and the quality and water content is spot tested yet again at the hydrant servicer before going into the wing.
The simple answer is that you break that chain of custody and inspection by putting it in your dirty old aircraft and taking it out again and you just dont know what you have got, in terms of contaminants, fungus, sediment, water, etc. etc. Aircraft operating in tropical environments and subject to high relative humidity, heating/cooling cycles etc. frequently experience microbial growth which is treated using special additives eg Biobor JF or others. But there's no easy on-site spot test for these additives and anything other than the basic contaminants, so you really have no idea what you might get UNLESS its one of your own company fleet in which case you will have the assurance (you hope!) that the overfuelled aircraft was fuelled according to your own policy and you and your insurers would be a bit more relaxed about taking it.
The other thing that makes it a pain is that while large aircraft are commonly fuelled under pressure from a 'hot hydrant system' which is kept pressurised and is set into the apron, the reverse process is not possible. So it usually has to be discharged into a bowser (like you would use for smaller aircraft or with AVGAS) and there you have another point of contamination, need to inspect, certify, etc etc. Its a dogs breakfast, a lot of extra work, huge amounts of implied risk, and its easier just to dump it into power kerosene. because the spec is usually the same (except that Jet has a restriction on freeze point, power or heating paraffin/kerosene has a restriction on smoke point).
Pinkman
Aircraft fuel is subject to a chain of custody type arrangement and is incredibly well tested, inspected and certified, even though each batch is slightly different because of small variations in its distillation charateristics, the refinery it came from and the processes employed there (eg in catlytic cracking, Sulphur removal etc.), and the crude it was distilled from. Even the minute amounts of water and sediment it picked up during distribution is removed just before final storage and the quality and water content is spot tested yet again at the hydrant servicer before going into the wing.
The simple answer is that you break that chain of custody and inspection by putting it in your dirty old aircraft and taking it out again and you just dont know what you have got, in terms of contaminants, fungus, sediment, water, etc. etc. Aircraft operating in tropical environments and subject to high relative humidity, heating/cooling cycles etc. frequently experience microbial growth which is treated using special additives eg Biobor JF or others. But there's no easy on-site spot test for these additives and anything other than the basic contaminants, so you really have no idea what you might get UNLESS its one of your own company fleet in which case you will have the assurance (you hope!) that the overfuelled aircraft was fuelled according to your own policy and you and your insurers would be a bit more relaxed about taking it.
The other thing that makes it a pain is that while large aircraft are commonly fuelled under pressure from a 'hot hydrant system' which is kept pressurised and is set into the apron, the reverse process is not possible. So it usually has to be discharged into a bowser (like you would use for smaller aircraft or with AVGAS) and there you have another point of contamination, need to inspect, certify, etc etc. Its a dogs breakfast, a lot of extra work, huge amounts of implied risk, and its easier just to dump it into power kerosene. because the spec is usually the same (except that Jet has a restriction on freeze point, power or heating paraffin/kerosene has a restriction on smoke point).
Pinkman
Last edited by Pinkman; 8th Aug 2007 at 14:10. Reason: pore spelin
Pinkman
I started my comments with
ie I am fairly aware of the quality issues and system in so far as I was the accountable manager.
My point was a response to the statement that defuelled fuel could go back into an aircraft of the same company, but no-one else's.
I don't get that; there can be no differentiation on safety grounds, although I can see a commercial desire not to throw away paid-for fuel.
We did not differentiate; IF we had a tanker(s) available and were able to defuel at all, we would put it into the tanker (s), subject it to stringent contamination and specification checks, and eventually put it back into main storage, where it would re-enter the quality control system. The tankers would go back into use for normal deliveries, and be checked in the usual way. We would credit the airline concerned, minus the whole cost of this laborious operation, which usually meant that he paid us rather than the other way round.
As I said, if the fuel failed the quality checks we would not reload it into any aircraft, company or otherwise, or return it to the supplier, instead using it for fire practice, running the fire trucks, or heating.
It's the bit about "It's OK to reload defuelled fuel into the same company's aircraft but no-one else's", that I don't like. Not in my book, it's not.
PS I know Tristar 500 mentioned decontamination checks; it was Exeng's earlier post I quoted and responded to. But even with such checks, the problems of storing that fuel until called for are huge; will the airline hire in replacement vehicles while 2 or 3 are full of "their" fuel? Only very big airports/fuel depots have large fleets of into-plane fuelling tankers. Tanker storage is subject to the same QA, Fire, Environmental and H&S controls as the main storage, and you can only store in a tanker for a short time.
I started my comments with
When I sold fuel, among other airport services,
My point was a response to the statement that defuelled fuel could go back into an aircraft of the same company, but no-one else's.
I don't get that; there can be no differentiation on safety grounds, although I can see a commercial desire not to throw away paid-for fuel.
We did not differentiate; IF we had a tanker(s) available and were able to defuel at all, we would put it into the tanker (s), subject it to stringent contamination and specification checks, and eventually put it back into main storage, where it would re-enter the quality control system. The tankers would go back into use for normal deliveries, and be checked in the usual way. We would credit the airline concerned, minus the whole cost of this laborious operation, which usually meant that he paid us rather than the other way round.
As I said, if the fuel failed the quality checks we would not reload it into any aircraft, company or otherwise, or return it to the supplier, instead using it for fire practice, running the fire trucks, or heating.
It's the bit about "It's OK to reload defuelled fuel into the same company's aircraft but no-one else's", that I don't like. Not in my book, it's not.
PS I know Tristar 500 mentioned decontamination checks; it was Exeng's earlier post I quoted and responded to. But even with such checks, the problems of storing that fuel until called for are huge; will the airline hire in replacement vehicles while 2 or 3 are full of "their" fuel? Only very big airports/fuel depots have large fleets of into-plane fuelling tankers. Tanker storage is subject to the same QA, Fire, Environmental and H&S controls as the main storage, and you can only store in a tanker for a short time.
Last edited by old,not bold; 8th Aug 2007 at 17:11.
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Old not Bold
ONB- oops sorry - didnt see that bit on your post - apologies for preaching to the converted.
But I think we are on the same page because although I worked for the Oil Company, if I was the airline, I wouldnt do it either. But having said that, our SOPs didnt allow us to put it back into the AIRPORT day tanks.
In most cases it was downgraded to 'DPK' (Dual Purpose Kerosene) and it went to who - knows - where.
Maybe we were just overcautious in deepest darkest Africa.
Again, apologies.
But I think we are on the same page because although I worked for the Oil Company, if I was the airline, I wouldnt do it either. But having said that, our SOPs didnt allow us to put it back into the AIRPORT day tanks.
In most cases it was downgraded to 'DPK' (Dual Purpose Kerosene) and it went to who - knows - where.
Maybe we were just overcautious in deepest darkest Africa.
Again, apologies.
Pinkman, ego te absolvo, as we would say on JB, and your post was full of good stuff from which I've learned a lot, especially if that's how it was done in darkest Africa. Wish I could claim that.
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'tis true , ....for all the disbelievers out there....
" B747 G-**** LHR-CWL CRUISE
50 tonnes of fuel dumped during positioning flight to Cardiff
The flight was a positioning flight which departed late and the crew were trying to beat the jet ban. Dispatch passed a message stating the aircraft was approx 6 tonnes too heavy to land in Cardiff. The flight departed and the figures were re-checked and it was discovered that the aircraft was 50 tonnes too heavy. The situation was discussed with Flight Tech Dispatch and the Ops Control manager gave permission to dump fuel down to safe level .
50 tonnes of fuel jettisoned. "
" B747 G-**** LHR-CWL CRUISE
50 tonnes of fuel dumped during positioning flight to Cardiff
The flight was a positioning flight which departed late and the crew were trying to beat the jet ban. Dispatch passed a message stating the aircraft was approx 6 tonnes too heavy to land in Cardiff. The flight departed and the figures were re-checked and it was discovered that the aircraft was 50 tonnes too heavy. The situation was discussed with Flight Tech Dispatch and the Ops Control manager gave permission to dump fuel down to safe level .
50 tonnes of fuel jettisoned. "
Last edited by cirrus01; 11th Aug 2007 at 14:59.
Where.......?
PS Didn't the crew know the weight at take-off? And the MLW? And the sector burn in Kgs?
Am I so old-fashioned I don't understand how they can go without these numbers? Or are we blaming the computer?
PS Didn't the crew know the weight at take-off? And the MLW? And the sector burn in Kgs?
Am I so old-fashioned I don't understand how they can go without these numbers? Or are we blaming the computer?
Exactly....and I'd still be interested to know where they went to jettison 50 Tonnes of Jet A1.
Surely it wasn't done on route? Or was it? How long does it take? Or to put it another way, how many miles are covered during the process?
What FL was it done at? If on route, that would have been quite low, wouldn't it, unless a special climb for the purpose was carried out.
So many questions, so little time. Does anyone know some or all the answers?
I don't, obviously. This is outside my experience/knowledge.
PS If, say, it takes 15 mins to lose 50,000 Kgs, my guesswork says that means 500-600 Kgs per mile, if flying a straight line during the whole process. Would that be in the ball-park? Or miles away? Presumably the fuel forms a mist as it emerges into the slipstream/vortex, in non-scientific terms. Then what? I would imagine that 500Kgs per mile/313gm per metre (if that's anywhere near the right figure) is negligible at ground level, especially after dispersal by winds, but what are the facts?
Surely it wasn't done on route? Or was it? How long does it take? Or to put it another way, how many miles are covered during the process?
What FL was it done at? If on route, that would have been quite low, wouldn't it, unless a special climb for the purpose was carried out.
So many questions, so little time. Does anyone know some or all the answers?
I don't, obviously. This is outside my experience/knowledge.
PS If, say, it takes 15 mins to lose 50,000 Kgs, my guesswork says that means 500-600 Kgs per mile, if flying a straight line during the whole process. Would that be in the ball-park? Or miles away? Presumably the fuel forms a mist as it emerges into the slipstream/vortex, in non-scientific terms. Then what? I would imagine that 500Kgs per mile/313gm per metre (if that's anywhere near the right figure) is negligible at ground level, especially after dispersal by winds, but what are the facts?
Last edited by old,not bold; 11th Aug 2007 at 13:31.
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744 fuel dump rate
http://www.pprune.org/forums/showthread.php?t=81634
So you see what it looks like: http://www.youtube.com/watch?v=gAbJgrqkBoI
So you see what it looks like: http://www.youtube.com/watch?v=gAbJgrqkBoI
Thanks for that; it looks as though it would take 30 minutes or so to lose the 50 tonnes, thus spreading the fuel twice as far as my rough guess above, assuming the aircraft wasn't circling....
So, in the case of this LHR-CWL positioning flight, if it was done at all was it done on route, over the sea, or somewhere specially designated?
Does anyone know?
There's no news story here; 250 Kg per mile, as a mist at altitude, is not significant. I'm merely curous, and not a journalist in the first place.
So, in the case of this LHR-CWL positioning flight, if it was done at all was it done on route, over the sea, or somewhere specially designated?
Does anyone know?
There's no news story here; 250 Kg per mile, as a mist at altitude, is not significant. I'm merely curous, and not a journalist in the first place.
Warning Toxic!
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The flight takes 25+ minutes. Dumping that alleged quantity would take 25+ minutes, all at least 6000' above ground level. The whole of the south of England wasn't going to go up if someone started a car engine! Nobody would even sniff it- it will vaporise. Overweight landings are 'an emergency only procedure' and not to be used in the course of normal operations. Fuel dumping is an 'emergency only procedure' as well- there are subsequent ramifications to the fuel gallery and engineering procedures.
I still find the alleged explanation garbled. It may well have taken place, but the hints at confusion and lack of knowledge don't make any sense. It is standard procedure to confirm aircraft weights and all it takes is an eye to confirm fuel on board for the flight- all this is automatically in the FMS system so full that knowledge is confirmed by a computerised loadsheet. Nobody was 'caught out'. I suspect it was late reassignment of a heavily fuelled aeroplane to maintenance 25 minutes away. Cardiff is not that long for a max landing weight 747. But before too many expressions of astonishment are made, I would like some positive confirmation of exactly what happened.
I still find the alleged explanation garbled. It may well have taken place, but the hints at confusion and lack of knowledge don't make any sense. It is standard procedure to confirm aircraft weights and all it takes is an eye to confirm fuel on board for the flight- all this is automatically in the FMS system so full that knowledge is confirmed by a computerised loadsheet. Nobody was 'caught out'. I suspect it was late reassignment of a heavily fuelled aeroplane to maintenance 25 minutes away. Cardiff is not that long for a max landing weight 747. But before too many expressions of astonishment are made, I would like some positive confirmation of exactly what happened.
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It has happened before where aircraft have been assigned to a positioning flight and then changed for whatever reason.
I canceled a positioning flight (Not a BA 744 flight!) last year where the aircraft was changed at the last minute and the aircraft which was assigned the positioning flight now had a full tank of fuel as it was due to fly elsewhere with passengers.
This meant it was out of trim with no pax on board.
There was no way of getting the fuel off the plane so the flight was canceled.
So it could be that something like that happened to the BA 744 but they chose to dump the fuel instead of canceling the flight, who knows!!
I canceled a positioning flight (Not a BA 744 flight!) last year where the aircraft was changed at the last minute and the aircraft which was assigned the positioning flight now had a full tank of fuel as it was due to fly elsewhere with passengers.
This meant it was out of trim with no pax on board.
There was no way of getting the fuel off the plane so the flight was canceled.
So it could be that something like that happened to the BA 744 but they chose to dump the fuel instead of canceling the flight, who knows!!
Last edited by 747-436; 12th Aug 2007 at 22:23. Reason: To clarify that it was not a BA flight I canx so trim problem not related to issue being discussed on this thread
Sounds possible, doesn't it, bearing in mind that if some of the posts on this thread are correct they set off not knowing about their extra 50 tonnes, and therefore not knowing there would be a trim problem and, if the extra 50 tonnes above MLW is enough to create one, without pax, presumably wondering why there was a trim problem.
Cancelling the flight was not an option, noting that they were airborne when advised of the extra fuel, if that information is right.
Would they have jettisoned the fuel to resolve the trim problem, the landing weight problem, or both?
Cancelling the flight was not an option, noting that they were airborne when advised of the extra fuel, if that information is right.
Would they have jettisoned the fuel to resolve the trim problem, the landing weight problem, or both?
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Trim Problem?
Passengers/freight badly positioned are what cause trim problems.
Numerous 747's departed LHR during the recent security scare with no passengers/freight and well in excess of 50,000kgs in the tanks.
No red herrings please, just facts.
Passengers/freight badly positioned are what cause trim problems.
Numerous 747's departed LHR during the recent security scare with no passengers/freight and well in excess of 50,000kgs in the tanks.
No red herrings please, just facts.
old, not bold
"..they set off not knowing about their extra 50 tonnes...." Not at all credible old but bold, how could they not know??..We don't just fill her up and launch into the air muttering " oh, I wonder how much fuel is on board"? There's the small matter of the Flight Crew agreeing/accepting the fuel figures with the ground personnel, the EICAS fuel display (flight deck) has to be checked when setting up the fuel configuration up prior to departure and the small matter of the Captain signing for the fuel prior to doors closed....
And I agree with woodpecker, over the years most of us on the Fleet have positioned empty aircraft with various fuel loads and I have never heard of problems with trim. The only way 50 tonnes of fuel and no pax would put you out of trim would be if the refullers had seriously stuffed up, and again the crew would most definitley be aware of that fact before starting engines.
Frankly there has been no mention of this alledged incident in the offices at BA, so either it was management foul up and a lid been kept on it ( and I'm not saying that's impossible but the stories always leak out) or more likely, IMHO, it's a good rumour/story but it didn't happen as has been described and ths thread should be put to bed.
And I agree with woodpecker, over the years most of us on the Fleet have positioned empty aircraft with various fuel loads and I have never heard of problems with trim. The only way 50 tonnes of fuel and no pax would put you out of trim would be if the refullers had seriously stuffed up, and again the crew would most definitley be aware of that fact before starting engines.
Frankly there has been no mention of this alledged incident in the offices at BA, so either it was management foul up and a lid been kept on it ( and I'm not saying that's impossible but the stories always leak out) or more likely, IMHO, it's a good rumour/story but it didn't happen as has been described and ths thread should be put to bed.