Fuel Dumps

[brine]

My cousin recently flew in a Singapore Airlines 747 which developed a fault 4 hours after take-off, turned back and had to dump a few thousand gallons of jet fuel before landing.

So what happens to the land or sea below when this happens? How much damage does it do to the creatures below?

It's big news when a ship founders and leaks fuel into the sea, but planes effectively doing the same don't get a mention.

No, I'm not a greeny, just wondering.

Bri :sad:

[ZH875]

The fuel is widely dispersed as it drops through the atmosphere, so you have very little fuel over a very wide area.

Far less worse than having diesel dumped on you by the Reds at an airshow.

[Reimers]

Given that they were at cruising level before the fault developed, we can assume they did not dump at a very low level (below 5000 ft). At higher altitudes, the fuel evaporates before it reaches the ground, so the air rather than the ground below is contaminated. The level of contamination is not that high, because the area that is overflown when dumping is huge.

[Daysleeper]

First off wrong forum.... ah now moved..:)
However as we're here.
1st Fuel Type - Ships and aeroplanes use different fuels. Most ships use heavy fuel oil which is a much harder substance to disperse, jet fuel is a relatively light fraction and will break up in the atmosphere much more readily.
2nd - Quantity - even a fully loaded 747 is only going to be dumping say two hundred tons of fuel MAX and probably a lot less. A (relatively) small ship may have several thousand tons of fuel on, plus whatever cargo it is carrying which may run to several HUNDRED THOUSAND tons of fuel, or crude or whatever.
3rd Dispersion.. while dumping fuel aeroplanes are traveling at a couple of hundred miles an hour the fuel will be atomized as it comes out of the dump chute and held in suspension by the atmosphere, it will eventually settle to earth or sea, but over a very large area and thus be very dilute... ships put it all in the one place.
4th some experiments.... first take 10 ml of diesel, go to the highest point in your house and on a very windy day throw it out the window...(downwind)....did anyone notice? no right now take 100ml of used engine oil... fill your kitchen sink with water and pour it in... wait till your wife/mother screams at her crockery getting ruined, my point in a nutshell.
All experiments conducted at your own risk, PPRUNE takes no responsibility for destroyed plates, plumbers fees or other unintended consequences. :E

[skiesfull]

Dump 200 tonnes of fuel from a fully laden B747-400???? Most 744's with a max t/o weight of 397 tonnes, can only carry 175-176 tonnes, which is full tanks, so where do you get this 'fact' from?
Unless the 744 had an engine defect causing an in-flight shut-down, fuel dumping is not mandatory above max. landing weight. An overweight manual landing is permissable.
Above 6000ft. it is estimated that the jettisoned fuel will evaporate- dependant on atmospheric conditions.