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Dumping Fuel ...please explain.

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Comparitively cheap vs petrol even if that's in US gallons.

 

I'd assume the dump might well have been more than to get it down to standard MTOW since it was a blown tyre issue - possibly there's some formula for that?

 

I should think that the cost of lost fuel would have been in the order of 3-4 times the replacement cost of 2 tyres.

So much for cost savings by running the tyres longer than recommended if that was the case. Chances are the $$$ saving by landing a dozen or so times more than they should might have only come to a few grand if the blowout hadn't occurred.

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Well I'm just going from personal observation of United aircraft over the years and one annoying experience, the tyre(s) may have been damaged by FOD and created more of course, be interesting to see what they discover.

 

it's kero rather than petrol in essence, Ry, with a lot of additives but yeah cheaper than car fuel, I guess quantity of buy affects the prices as well.

 

Dumps are pretty rare NS, to accommodate your idea the entire jet fleet would be lugging around the extra weight to off-load in an emergency, and you'd have to have aircraft equipped to take the fuel,which military tankers can do, but they are not everywhere and civilian pilots are not exactly used to being tanker pilots which essentially they would be. In theory a good idea, in practice a lot of expense against rare need and the amount that aircraft dumped is literally a spec in the ocean compared to what is consumed world wide in a day of aircraft flying or even what was being burned elsewhere whilst it was dumping.

 

Sounds like a lot, it isn't really.

 

Cheers

Edited by chrisg

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What i want to know is: why don't the big jets with 40,000+ liters of fuel capacity have a retractable fuel nozzle? so a fuel tanker could fly up behind it, drain some fuel, land, discharge it back into holding tanks, go back up and drain some more till the aircraft is back to safe landing weight?

Because the cost of maintaining tankers to do just that at even a few major airports would be astronomical.

Add in that you need highly trained (read expensive) crews to do air to air refuelling (or defuelling in this case), plus all the commercial aircraft would have to be fitted with retractable probes or hose and drogues and all the associated plumbing systems and pumps to transfer the fuel to the nozzle, whilst still keeping the fuel dump equipment just in case.

The overall cost would just be too high.

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Dumps are pretty rare NS, to accommodate your idea the entire jet fleet would be lugging around the extra weight to off-load in an emergency, and you'd have to have aircraft equipped to take the fuel,which military tankers can do, but they are not everywhere and civilian pilots are not exactly used to being tanker pilots which essentially they would be. In theory a good idea, in practice a lot of expense against rare need and the amount that aircraft dumped is literally a spec in the ocean compared to what is consumed world wide in a day of aircraft flying or even what was being burned elsewhere whilst it was dumping.

 

Sounds like a lot, it isn't really.

 

Cheers

So a second set of landing gear isnt a dead weight? it also is very rarely used piece of equipment, but its still equipped to the 747 (ignoring the fact its an ancient design, and not many others have the same redundancy in their aircraft)

 

Because the cost of maintaining tankers to do just that at even a few major airports would be astronomical.

Add in that you need highly trained (read expensive) crews to do air to air refuelling (or defuelling in this case), plus all the commercial aircraft would have to be fitted with retractable probes or hose and drogues and all the associated plumbing systems and pumps to transfer the fuel to the nozzle, whilst still keeping the fuel dump equipment just in case.

The overall cost would just be too high.

How about; letting the military of each country take care of defuelling the jets? there is almost always, an airbase near every major airport (in regards to flight time, not physical location), so sending up a military tanker up to do it shouldn't be to much of problem, they do it regularly in their training ops; and we would get the added benefit of the military crews gaining experience in air to air refueling/defuelling. Could even take it one step further and have the military keep the fuel they take (which would otherwise be discarded into the environment) for whatever "training" exercises they would usually do with their own aircraft/fuel. Miltray end up saving money on fuel costs, airlines save face from the public over fuel dumping episodes across our environments (no matter how small the impact), it would pay off eventually, win win from how i see it ;P

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Nobody: Cool. Now who will pay for the refit of ALL civilian aircraft with a suitable drogue for this.

 

Furthermore, a military tanker will NOT work. The tanker works of a pump that pumps OUTWARDS. Not inwards. You can't just 'turn it around'.

 

It's an unfeasible idea. It's an interesting idea, but at the end of the day, more fuel would be burnt and being pumped into our atmosphere than what you would save to try and achieve this (Especially considering how rare)

 

AD

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:)

 

The 747 doesn't EXACTLY have an extra set of wheel bogies, they are all used, required for landing and taxi balance plus fore and aft stability on the ground. What MEC said is true, but it's a function of the strength of the aircraft that in extremis if some of the bogies fail to extend the aircraft weight can still be carried by the remainder, the aircraft however would not be as stable.

 

Some tankers can act as receivers as well AD, but by no means all of them.

 

Quire apart from cost and the rarity of dumps though the world tanker fleet outside the US is far from large, we have 5 KC-30s, all at Amberley, hardly covers the whole country except by accident, the UK has a few, France, Italy and Japan, although not sure if delivered yet, they are pretty thin on the ground after that.

 

The US has perhaps 75 or 80, depends how many of the old KC-135s are airworthy, but around sixty KC-30s, the other nations it's single digits and not all capable of being receivers.

 

Perhaps 100 aircraft all up, most in the US, perhaps half, although probably less, able to receive.

 

In-flight refueling is not a passive maneuver for either aircraft, I've done hundreds, perhaps more of them and could never relax for one second. That's as receiver but the tanker requires precision specialist flying to make my job just a little easier.

 

A nice idea but not going to work for all the reasons given.

 

Cheers

Edited by chrisg

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Isnt this the sort of thread Cybes should be in? OI!

Been out all day and just saw the explosion of this thread since last night.

 

I'd just be parroting stuff heard here already anyway - 3rd hand, at that. I was only ever personally involved with private light civil aviation (single and twin piston engines, up to 6 seats); whilst I did have contact with people in heavies and choppers for the first ~25 years of my life, anything I have to say on those is not authoritative.

 

Looks like Chris is all over this one, anyway. ;)

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Another thing to point out, by dumping fuel and returning to a nearby airport they can stay close to the ground.

 

Imagine if a piece of rubber had damaged the integrity of the hull, if they had tried to reach cruising altitude and lost cabin pressure there would have been a whole lot more complications.

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Nobody: Cool. Now who will pay for the refit of ALL civilian aircraft with a suitable drogue for this.

 

Furthermore, a military tanker will NOT work. The tanker works of a pump that pumps OUTWARDS. Not inwards. You can't just 'turn it around'.

 

It's an unfeasible idea. It's an interesting idea, but at the end of the day, more fuel would be burnt and being pumped into our atmosphere than what you would save to try and achieve this (Especially considering how rare)

 

AD

 

the 747 carries 238,604 liters (422,000 pounds), if the plane had to shed 127,000 pounds of fuel to make it to the safe landing weight (295,000 pounds), thats about~ 100k liters, I don't think a tanker is going to burn the majority of that getting up and back down again, unless you did 2 or more trips (no idea on the actual numbers, but boeing quotes it as enough fuel to get from melbourne to la, so a tanker flying for ~2hours shouldnt use anywhere near that)

 

the point to my whole idea was; this has been a known problem for decades, and we don't have a solution to it, viable or not.

 

 

:)

 

The 747 doesn't EXACTLY have an extra set of wheel bogies, they are all used, required for landing and taxi balance plus fore and aft stability on the ground. What MEC said is true, but it's a function of the strength of the aircraft that in extremis if some of the bogies fail to extend the aircraft weight can still be carried by the remainder, the aircraft however would not be as stable.

 

Some tankers can act as receivers as well AD, but by no means all of them.

 

Quire apart from cost and the rarity of dumps though the world tanker fleet outside the US is far from large, we have 5 KC-30s, all at Amberley, hardly covers the whole country except by accident, the UK has a few, France, Italy and Japan, although not sure if delivered yet, they are pretty thin on the ground after that.

 

The US has perhaps 75 or 80, depends how many of the old KC-135s are airworthy, but around sixty KC-30s, the other nations it's single digits and not all capable of being receivers.

 

Perhaps 100 aircraft all up, most in the US, perhaps half, although probably less, able to receive.

 

In-flight refueling is not a passive maneuver for either aircraft, I've done hundreds, perhaps more of them and could never relax for one second. That's as receiver but the tanker requires precision specialist flying to make my job just a little easier.

 

A nice idea but not going to work for all the reasons given.

 

Cheers

Ah good to know. I always thought that there would be atleast 1 tanker for every X amount of fighters, didn't realise just how rare fuel tankers are in the world.

 

I know its extremely difficult to refuel in air, watched a fair few documentary's on it, maybe one day in the future when drones and their flight software are advanced enough, that it might become feasible in practice to actually do it. It just seems an incredible waste to dump 50K-150K litres of perfectly good fuel.

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Thanks for being reasonable nobody. But you still didn't address who should pay for the refit of the 7(x)7's or the A3(x)0s.

 

They're not equiped for it, and I honestly do not know whether they can be retrofitted. That is nowhere near my speciality. But it is a serious consideration.

 

Further, how often do we have fuel dumps? Often? Nope. But how much fuel will have to be burnt not just to get the tanker there, but to 'maintain' their level of competance in dealing with these emergencies. So once every x weeks/months they have to fly for an occasional emergency. I see more fuel getting destroyed by the planes flying and training than what is saved from dumping.

 

Don't even mention what goes wrong with a mishap with air-to-air refueling. But you can youtube it if you want. It's very common. Professional military pilots screw up who do frequent training with this. What about a civilian operator who likely wouldn't do frequent training (Costs!!!).

 

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Thanks for being reasonable nobody. But you still didn't address who should pay for the refit of the 7(x)7's or the A3(x)0s.

 

They're not equiped for it, and I honestly do not know whether they can be retrofitted. That is nowhere near my speciality. But it is a serious consideration.

 

Further, how often do we have fuel dumps? Often? Nope. But how much fuel will have to be burnt not just to get the tanker there, but to 'maintain' their level of competance in dealing with these emergencies. So once every x weeks/months they have to fly for an occasional emergency. I see more fuel getting destroyed by the planes flying and training than what is saved from dumping.

 

Don't even mention what goes wrong with a mishap with air-to-air refueling. But you can youtube it if you want. It's very common. Professional military pilots screw up who do frequent training with this. What about a civilian operator who likely wouldn't do frequent training (Costs!!!).

 

AD

Well, the ideally the aircraft industry would bake this idea into their designs going forward, with older aircraft being forced out of service after a certain time period (like a few decades, 747's are getting really old now). Think of it like another feature baked into the base model. It was just an idea, admittedly one full of pricy holes for such an rare event, and one that would probably take years of planning to fully flesh out. But to give an example; the black box recorder was invented to solve a problem, to find out what/why/when something went wrong, so future designs could benefit to make flying safer, id like to see similar advancement to other "rare events" like emergency fuel dumping.

 

And like i said, Ive seen a fair few documentary's, everything from the nozzle on the receiving aircraft being ripped off, and then smashing into the cockpit of said aircraft, to the whole fighter getting covered in fuel and then catching alight from getting to close to the tankers exhaust, lots can go wrong, but until something goes wrong, a solution wont be invented to solve it from happening in the future, chicken and the egg principle if you like :)

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;)

 

Well actually probably not AD, tanks equal drag equals more fuel burn. Just about every military aircraft I've had dealings with has the option for them, but that's so you can loiter and clean up to get design performance if required, on a civilian aircraft it would be non-optimal.

 

I do understand what you are thinking of Nobody, I vaguely recall the inventor of in- flight refueling even looked at it for extending airliner range, re-fueling not de-fueling, it was way cheaper to just build staging refueling landings places.

 

Tankers are very expensive, even though they are often in fact nearly always recycled airframes, btw I made a mistake up there, the bulk of the US tanker fleet is KC-10s, refurbed DC-10s and a superb aircraft despite the chequered history of the original airliner. But refurb is not really the case, a complete re-build is more accurate. The KC-30 can be built from new, but most, I think all are refurbs really, it's just the way tankers are. I mostly plugged into old V bombers and VC-10s unless cross-exercising with the USAF.

 

A hell of a lot can go wrong, and as you have seen, does - never had it happen but that's as much the tanker crews skill as mine. It's all those guys do, can't expect a civ pilot to have their degree of proficiency in that regard.

 

Very few air-forces really have the need, we do, but didn't have it for a long time, the US does, the UK same, France has some reason, Italy not really, its part of their NATO contribution really, Japan does.

 

Most air forces exist for border defense, so Sweden for example has no reason to have tankers.

 

Dumps really are rare.

 

What would be optimal would be for take off weight to equal landing weight - in small fighters that can be the case, without tanks, but on the big guys no, unless they can get far stronger and lighter materials, not to mention the hydraulics of gear, plus brakes and the ability to stop that inertia the imbalance will continue.

 

I should have a look and see what the margin is for the 787, I suspect it might be closer than the 747.

 

But really, so rare that although it sounds wasteful it's a simple decision to as noted by another stay close to safety, get weight down and get back on the ground, whilst overhead far more fuel is being burned anyway.

 

There is one tanker story from a long time back that I always found frightening but amusing, and had some echoes for me.

 

A KC-135 in Europe, just finished a tank chore and the crew suddenly smelt fuel. The boom operator rushed to the cockpit and said they had a major fuel leak - really the tanks are just bladders on the original floor.

 

Leak was right, thousands of gallons awash in the main body. No way to dump that.

 

The pilots fought all that moving weight down to a clean landing and a fire-fighter appeared in the cockpit about to fire-axe the cockpit door, which is sealed pretty well and the liquid would have headed into the lower reaches any way.

 

A very tired captain, probably just had enough for one day stopped him and said "Don't, you'll just get wet."

 

;)

 

Cheers

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Hi MEC, not seen you in a while ;)

Hi chrisg, haven't been around much for a while. I'm captivated by my children. We had our fourth child in Feb so plenty of little MECs pulling stuff apart & running amok! Still try and check in every couple of months or have a read when something significant happens out in the world. It's nice to see what all you smart people are thinking & conversing about.

 

I'd love to add more to the discussion but I think it's all been taken care of! There is a lot of knowledge, experience and simple good reasoning in here. :)

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Skyhawks had the buddy system where each was able to function as tanker or receiver. I believe the Vulcan bomber was likewise although the tankers might have been dedicated to that task.

 

Space is at a premium, having a 747 being able to function as a tanker would take away from available fuel space and increase weight and operating costs.

 

Given the rarity of the need to dump fuel - I doubt it has occurred more than 1,000 times ever with jet liners in literally millions of flights it's not really worth the trouble.

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Hi MEC, not seen you in a while ;)

Hi chrisg, haven't been around much for a while. I'm captivated by my children. We had our fourth child in Feb so plenty of little MECs pulling stuff apart & running amok! Still try and check in every couple of months or have a read when something significant happens out in the world. It's nice to see what all you smart people are thinking & conversing about.

 

I'd love to add more to the discussion but I think it's all been taken care of! There is a lot of knowledge, experience and simple good reasoning in here. :)

 

 

:)

 

4 !?!

 

Man, two plus two adult steps and a couple of adult sort of adopted are more than enough for me - do love that growing up phase though :)

 

Here's to family life :)

 

Yeah, interesting situation, well handled I think, not here, by the crew but yeah, it's one of those things, be interesting to see what the report turn up.

 

Yeah Ry, buddy is an option, confined to Mil though, I think the Vulcan's did have it but not totally sure, I think on those long range missions in the South Atlantic it was Victor tankers, but I'd have to check - usually i can just reach for a book, but, just moved ;)

 

Cheers

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Next thing that sends me loopy over this is just how much of this wasted fuel does hit the ocean ? At an approximate figure of 125,000 litres, I'm getting

more curious as to the percentage that would make land fall, or in this case ocean fall.

In the link it showed a fair amount of traffic coming in from over the ocean. I guess this traffic having to fly higher is not a problem for them.

 

So 10,000 ft is a good altitude for dumping fuel safely over the ocean ? What I mean is, there's little toxic impact for the stretch of ocean being dumped on ?

... Lastly the cost of all that wasted fuel ???

 

My emphasised piece of your post now makes me wonder why this plane could not have used 125,000 litres of fuel more constructively by

travelling at least some way towards it's eventual destination ? Or, landed it back at Sydney with most of the fuel intact, with less

grumpy passengers ... and less disruption to all the other States where flights were delayed .<< total noob questions.

 

MEC I don't expect you to have to answer my questions, but feel free if you want to ... it's more just me expressing my thoughts on

this particoolar situation ... :)

Your post has already generated good discussion so I wasn't going to add more when it's already been addressed, but here's my 2 cents.

 

Much has already been suggested about what quantity of fuel might make it to ground or sea, but there are a few good stories from people who have experienced a fuel dump incident here: http://www.airliners.net/aviation-forums/g...d.main/4102030/

One post that I found interesting was this: "And ironically, dumping fuel actually saves fuel. If the structure of all commercial heavy aircraft would have to be designed to sustain landings at MTOW, we would carry a lot more structural weight in every aircraft, and hence burn more fuel. "

 

One fuel dump I recall involved an extremely lucky Emirates A340 which dragged it's arse halfway down the main runway at MEL before taking out most of the antennas and barely clearing the fence! Very near miss & barely reported. Computers had been provided incorrect weight figures by a fatigued F/O & doubled checked incorrectly by an even more fatigued captain! This struggling aircraft dumped fuel over Port Philip Bay at midnight.

 

Regarding using fuel more constructively I'd first like to highlight that although the landing gear is capable of absorbing landing loads at Max Takeoff Weight, the structure of the aircraft is likely to sustain damage. Also, any aircraft suffering from a heavy landing requires significant maintenance inspection, so the aircraft will be out of service for several hours for inspection & whatever other time it takes to repair any damage found. With this in mind, and considering the damage already incurred from the suspected tyre failures (at the time of take off), it makes good sense to return to a base where there are resources such as personnel, equipment & logistics to return the aircraft to service ASAP.

 

Travelling on toward it's destination with the landing gear extended increases drag & limits the aircraft to low speed & low altitude, increasing fuel burn & reducing range significantly. As an example, that Emirates A340 flew clean, gear retracted, but unpressurised from Melbourne to Toulouse for final & extensive repair. Rather than making the trip in 2 legs it took 11! That is a pretty good example of an advantage of high altitude flight.

 

The delays across Australian aviation networks were due to the debris cleanup & runway inspections. Also the fact that airlines don't have much room to move with aircraft running tight schedules, quick turnarounds & usually no spare aircraft. There is no fat left in the airline business anymore. The cheapest airfares cut deep into service & product quality, and there is little elegance left in flying today. Perhaps economics contributed to United's 744 tyre failures. Then again, it's just as likely to have run over FOD that came off another struggling operators aircraft!

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I liked the attempt at saving the fuel by the Italian dude. He was gathering stuff just not the sort of stuff he was after... :P

 

Your last paragraph is fairly telling I think. Time equals money.

At least with this particular story it seems the only costs were monetary ones.

 

edit: Also, I meant to say earlier... Looking at the fuel dumping link, I was amazed by how much action is happening in our sky.

I know it's super busy, but seeing all those yellow planes like that, when they were heading for the strips, they were like bees to the honey pot :)

Edited by eveln

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edit: Also, I meant to say earlier... Looking at the fuel dumping link, I was amazed by how much action is happening in our sky.

I know it's super busy, but seeing all those yellow planes like that, when they were heading for the strips, they were like bees to the honey pot :)

And Flight radar doesn't show any of the general light aircraft movements in the area AFAIK, just the large commercial stuff (passenger and freight).

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:)

 

Sydney is pretty busy but use the same link to go have a look at Singapore, or NYC :)

 

Cheers

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:)

 

Sydney is pretty busy but use the same link to go have a look at Singapore, or NYC :)

 

Cheers

Ye done that in the past, and Heathrow, and JKF etc. Scary scary. It actually surprises me that there are so few incidents when you consider the number of aircraft movements daily around the world.

Just be thankful no-one came up with a cheap affordable car. Most people are bad enough with two dimensions to play with, three doesn't bear thinking about. /Shudder.

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:)

 

And yet even in the busy skies of the US and Europe except when in the pattern it is rare to see other aircraft as more than dots or contrails.

 

I was flying across the US a few years back, pre-9/11, riding the jump seat with a mate at the controls and a 727 coming the other way went by on our left a little lower and about 1,000 feet away, all in the cockpit thought it very unusual and those guys are up there most every day.

 

Nothing dangerous of course ATC must have been having a busy day, it was on the SFO/Chicago route.

 

But yeah, Ev's description of bees to honey is pretty on the mark ;)

 

Cheers

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edit: Also, I meant to say earlier... Looking at the fuel dumping link, I was amazed by how much action is happening in our sky.

I know it's super busy, but seeing all those yellow planes like that, when they were heading for the strips, they were like bees to the honey pot :)

And Flight radar doesn't show any of the general light aircraft movements in the area AFAIK, just the large commercial stuff (passenger and freight).

 

Because they'd all be at a lower altitude of course ... hopefully ;)

Hadn't even thought of that. Really don't want to see what's happening over the US. :\

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;)

 

Not all,

 

the link doesn't show military traffic or I believe light charter jets, the US looks crazy as do some areas of Asia but in reality ATC is pretty good these days most places - apart from occasional language difficulties ;)

 

Cheers

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I once shared a flat with a ATCer.

If his finger wasn't tapping the bench his foot was tapping. His speech was jerky. From memory he still had a sense of humour ...

And a girlfriend who happened to be a nurse.

Edited by eveln

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