Are private/commercial jets dumping fuel?

[Sunroof]

Okay so my neighbor (next to me at the marina) and I have a bet going on. I do not agree with his assessment but I thought I would get some answers from the private and commercial pilots on board here.

So here it is...................

At Lake Lanier north of Atlanta and directly in the pathway of jet traffic to Hartsfield and other airports, both my neighbor and I have noticed that after a week or so a very lite film of greasy dirt ends up on the boats at the marina. Both he and I dock sailboats on the lake. He claims that commercial and private jets "dump" fuel en route to the airport! I say, nonsense, why waste precious fuel and dollars and for what reason? Rather I suggested it could be the resulting exhaust that might have JP-4 residue. But logic would say that this would be everywhere given the thousands of planes flying around the country each day. Kerosene residue?

Right now his level of frustration is far greater then mine as it could be related to any pollution source, but he insists on jet fuel.

So, is he onto something here regarding fuel dumps? Seems far fetched to me.

Bob

[Gogar]

That's ridiculous.

I agree with your idea that it's just the particulate residue of the exhaust.

[Embraer]

jets rarely, rarely, rarely dump fuel. your film is probably caused by other boats and the water itself.

[Seahawk]

There are, unless the aircraft is having an emergency, very strict requirements on fuel dumping...I don't even know if newer airliners can even dump fuel.

The only reason to ever dump fuel is to get weight down in order to fly with an engine, or multiple engine, failures or get under max landing weight.

I did a lot of maintenance test flying and in order to test the fuel dump function we had to climb to over 8k feet, over water only, and hit the dump cycle for less than two seconds...we could visually observe the dump.

No airline would ever dump fuel needlessly.

[304065]

The takeoff weight of an airplane is usually higher than its landing weight, of course the difference is fuel. En route to the destination fuel is burned off and the airplane lands at a specified weight.

In a "Quick Return" scenario where something has gone horribly wrong with the aircraft after takeoff, fuel dumping is used to get the airplane down to a weight where it can safely land.

So the answer is, is it possible? Yes. Is it probable? No, unless you have read about some Quick Return type incidents occurring at the airport recently. They are notable enough that you, and we all, probably would have.

It's like the old joke-- a guy is looking under a streetlamp for his keys-- someone says, did you lose them here? And the guy says, "No I lost them down the block but the light is better here."

[GH85Carrera]

Jet fuel is EXPENSIVE!

They are not going to dump fuel unless it is vital for safety.

I bet a lot of boats have bilge pumps pumping oily fuel contaminated water from the bilge.

[bleucamaro]

Very unlikely its a fuel dump.

Is your marina in the landing path or take-off path? If in the landing path, engines are at or just off idle, so very little emissions. If in the take-off path engines are at full throttle and much more chance of it being exhaust residue.

The more likely cause is exhaust residue from other boats in your marina.

[lane912]

if JP-5 is about 4.50 a gallon..... and a 707 can hold 23,000 gallons of fuel.....

[stomachmonkey]

With the cost of fuel airlines would dump luggage and passengers before dumping fuel if they thought they could get away with it.

[lane912]

it would cause a bit more than "a little residue on the hull"

[beepbeep]

Chemtrails! They are after us, I tell you!

[cashflyer]

Most boat engines exhaust into the water.
All exhaust contains residue, and 2-cycle exhaust contains more.
Poorly maintained engines add to the problem.

I think this is a more likely source of your lake pollution.

[lane912]

^^^^^
I.E.
Your friend with the tinfoil hat is causing the residue on his boat with his boat-

[onewhippedpuppy]

Originally Posted by cashflyer

Most boat engines exhaust into the water.
All exhaust contains residue, and 2-cycle exhaust contains more.
Poorly maintained engines add to the problem.

I think this is a more likely source of your lake pollution.

Bingo. Ever see how a poorly tuned two stroke outboard can smoke? It will definitely take care of nearby mosquitoes.

[Porsche-O-Phile]

Yep, very rare. Highly unlikely that's what's happening.

[gordner]

Fuel dumping essentially never happens anymore. Private jets do not even have the capability normally nor do most new commercial airliners. I had an in flight emergency not that long ago and my pilot was told to circle with the broken aircraft until light enough to land or put ot down over gross if that was not possible. Under no circumstance would they allow a dump in the modern age unless lives are truly on the line, wihich is rare as the reality is you can land heavy, it just costs a lot of money for the aircraft owner in abnormal occurence inspection items.
Jet exhaust however leaves a greasy residue on everything in the area, working at the airport you can see it on a clean car by the end of the day.

[legion]

The jets are not dumping fuel. The residue is from boats.

[scottmandue]

I believe you guys that they are not dumping fuel.
However standing curbside at LAX waiting to be picked up the place reeks of kerosene... I get light headed waiting for my ride!

[legion]

Originally Posted by scottmandue

I believe you guys that they are not dumping fuel.
However standing curbside at LAX waiting to be picked up the place reeks of kerosene... I get light headed waiting for my ride!

Jets at idle seem to give off a powerful kerosene smell. I imagine there are lots of spills and drips on the tarmac as well.

[BRPORSCHE]

Chemtrails man.