Dumping Fuel

[Speedbird744]

How actually do pilots dump fuel and where?

[SLT]

The in's and out's will largely depend on the aircraft type, however the basics will be the same. On the A330, fuel is jettisoned from the inner wing tanks, and is pumped out by both the main and the standby pumps. It pumps at the rate of approximately 1000kg per minute. The jettison will stop at either a preset fuel remaining, or at a number of other points, which are detailed in the manual. The fuel exits via one of the inboard flap track fairings on each side. To get it to jettison, you follow the procedure in the manual, which simply involves 2 button-presses.
When dumping, it is important to be aware of your situation and to tell ATC. The A330 manual does not recommend dumping at less than 5000ft, to allow the fuel time to evaporate etc. ATC will route other aircraft away from you, to stop them becoming affected by your dumping. It is also unwise to jettison near to Cb's and it is unwise to dump while in a turn of more than 90 degrees - to avoid ingesting your own fuel trail - bad news!!

Hope this helps!!!

SLT :)

[Old Dog]

SLT, mindful of the fuel vapour, would you jettison fuel while in a standard holding pattern, or would you do an extended leg hold pattern, or just dog-leg? What about wind aloft?

Appreciate your view in this matter.

[ 27 October 2001: Message edited by: Old Dog ]

[SLT]

Not really thought about that one to be honest..... Both times I've had to dump fuel, we had a lot of open ocean to do it in! However my opinion, for what it's worth is this :

I don't think I would jettison in any sort of holding pattern if I could avoid it. Certainly not in a terminal area. I would much rather fly in a straight line if at all possible while dumping. If that wasn't possible, then a very large box-shape pattern it would be, giving plenty of time for the trail to dissipate. I guess that dog-legging as you suggest would also be an option. The wind I would imagine would make the trail drift downwind, however the A330 QRH suggests not dumping at below 5000 ft. Therefore I imagine it takes about that for the trail to evaporate. Someone else probably can give you a better answer to that one.

I think the key to the whole thing is to liase with ATC, and ensure that there is no other traffic around you - granted, this may not always be possible. Both times we did it, we a) were in open ocean with no, or very little other traffic. And b) we made the decision early enough so we were able to dump while flying in a straight line to our diversion. Perfect circumstances really! In any event, I would ensure that I had plenty of space to fiddle about in before I jettisoned!

Hope this helps!! Quite though provoking - thanks for that!! :)

[GotTheTshirt]

SLT,
Bearing in mind that many aircraft do not have dumping cababilty what would be the reaon behind dumping. Is it just to get the aircraft down to a landing weight after a problem or did the problem require you to dump??

[pigboat]

If your ops manual doesn't specify, here's a quick rule of thumb. Once you've determined your requirement to dump fuel, advise ATC and request a dump heading. Once you're established, they'll advise you when to start dumping, you avise them when you're finished, and they'll give you vectors back to the airport.

[MrWoollie]

The method of dumping can vary from aircraft to aircraft. Some use pumps (C130) and some use a gravity dump (B707). The gravity system is much slower, max of 3760 lbs/min.

Dump height from the manuals is usually above 5000ft AGL or higher.

Do not dump in a holding pattern for all the above described reasons plus what happened to me recently. The FO was flying and did a 180 deg turn while I was relieving myself. We got a very strong fuel smell through the aircon/pressurisation system. :mad:

[Checkboard]

In Australia:
FUEL DUMPING IN FLIGHT
CAR 150(2)(d) regulates the dropping of anything, including fuel, from an aircraft in flight. Additionally, Air Navigation (Fuel Spillage) Regulations prescribe penalties for the unauthorised release of fuel from an aircraft for other than in an emergency.

When fuel dumping is required, the pilot in command should request authority from ATC before commencing a fuel dump, and must:[list=a] notify ATC immediately after an emergency fuel dump;
take reasonable precautions to ensure the safety of persons or property in the air and on the ground; and
where possible, conduct a controlled dump in clear air above 6000 ft and in an area nominated by ATC[/list=a]

Dumping in a holding pattern is a little silly.

[SLT]

The main reason we dumped (both times) was simply to get the aircraft down to landing weight. We were approximately 25 tons above Max Landing Weight at the time and so dumped that amount of fuel. Rather an expensive exercise really! Obviously you still have the option to land overweight if you don't have the time to dump, however if you do have the time, and subsequently land overweight and do some damage, I imagine that the subsequent board of inquiry's first question would be "Why didn't you dump?"

Obviously, nothing takes away the commander's authority to land immediately (overweight if necessary) if he/she feels the flight to be in immediate danger.

I can't think of a fault which might actually require you to dump fuel as part of the drill. Of course that doesn't mean there isn't one!!

Cheers all :)

[Longhauler]

Although I have not dumped fuel myself, one piece of advice I have been given is that you can dump fuel in a standard holding pattern as long as you set V/S +200 or so which will prevent flying back into the dumped fuel.

[QAVION]

"Obviously, nothing takes away the ommander's authority to land immediately (overweight if necessary) if he/she feels the flight to be in immediate danger."

....bearing in mind that there can be factors other than weight to consider. On a 747-400, for example, CG is one of these (as there may still be fuel in the Horizontal Stabiliser) tank in the tail of the aircraft). You don't want to be too tail heavy for landing.

(Speedbird 744) Fuel dumping on the 747-400 is somewhat similar to that described by SLT for the Airbus. The dump control computer (A or B) is selected via a knob on one of the overhead panels, the desired remaining fuel qty is dialled in by the crew using another knob and the jettison valves are opened with two pushbutton switches (on the same panel), allowing fuel to be pumped from two nozzles in the trailing edge of the wings. The nozzles are just outboard of the Outboard Ailerons. The Jettison Valve switches are guarded with hinged plastic caps to prevent accidental activation.

Unwanted fuel is dumped from the Horizontal Stabilizer Tank, the "Centre Wing" Tank and the inboard (wing) Main Tanks by high capacity pumps in those tanks (not the regular "boost pumps" in the main tanks however, as these are required to maintain the fuel flow to the engines).

When the fuel level has reached the selected target, the dumping is automatically stopped ... at which time, the crew put the dumping controls on the overhead panel back to normal.

Note: Fuel Jettison panels may vary from 747-400 to 747-400. For example, some have a "MLW" selection which automatically dials in the correct amount of fuel to be dumped to ensure that the aircraft will be at or below Max Landing Weight.

Regards.
Q.

[rr892igw]

I've dumped 60 tons out of a b777 as we were
diverting to an enroute alternate as one of
the pax requires more medical attention than we could provide.
we did it with radar vectors similar to a very very large downwind/base/final,while descending.The fume smell is stronger than
what you get while filling up your car at the gas station.
Don't quite see the logic in Longhauler idea of fuel dump and climb as the reason for most fuel dump is to land earliest possible which you've to descent in the first place.
Never do it in a holding pattern,you'd
probably amuse alot of people on the ground. :rolleyes:

[GPWillcox]

On a 747-4 I lost #2 just after liftoff on a Taipei/LAX flight and required dumping for about one hour to get down to landing weight. I set up a holding pattern out over the water at 6000' and did 30 mile legs. Kept the 400+ pax informed and a round of free drinks from me. We landed got a rather fast repair on a broken fuel line and were underway in time to stay duty time legal. Great CRM from all my crew and support folks.
Be careful about rushing to land over Max landing weight. Lots of headaches from the paperwork and your aircraft will definitely be out of service for quite awhile.

[2XL]

Whilst I also fly the 767, there is a good summary of fuel dumping from the 767 at www.smartcockpit.com (http://www.smartcockpit.com) click on 767 index.

The minor variation I have observed is the jettison flow rate, Boieng claims 1200 kg/min whilst I am aware of some 767 operators using 1100kg/min.