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There are a couple of questions about the emergency procedure of fuel dumping, used to reduce the weight of airplanes to be able to land.

This is certainly interesting, regarding environmental affects, safety aspects, and maybe some archaic fascination for huge fuel-air clouds.

How relevant these questions really are depends on how often fuel dumping is done.

But I don't know how often it is actually done, in incidents per year globally.

I understand that the procedure is used only in emergency cases, but not only in very few very extreme situations. It's about getting the weight down to be able to land safely, and the overweight is from fuel not yet used up on the flight.

So the procedure is needed whenever there is a need to urgently land, and there is not enough time to burn the fuel in flight.

That seems to mean that severe medical emergencies of individual passengers may be a reason? That happens much more often than drastic technical problems I assume, so it would be a strong factor.

Now, I'm interested in some rough total estimate about how often fuel dumping happens, and the main factors, like minimal emergency cases that can lead to a fuel dump.

I'd simplify the scope by considering only commercial aviation, ignoring military and general aviation - but I do not see that as important, use the data you have at hand.

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    $\begingroup$ Perhaps specify if you mean civilian or military aviation. Bare in mind that most military aviation records may be sealed (or non-existent) $\endgroup$
    – Matthew Peters
    Commented Oct 1, 2014 at 20:31
  • $\begingroup$ you could search dump fuel on the avherald.com for a quick gander (not a full sample though) $\endgroup$
    – ratchet freak
    Commented Oct 1, 2014 at 20:46
  • $\begingroup$ @MatthewPeters good point, thanks! $\endgroup$
    – Volker Siegel
    Commented Oct 1, 2014 at 20:58
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    $\begingroup$ @VolkerSiegel except it doesn't report all incidents (in part because the guy doesn't get all reports or the country would otherwise be misrepresented) $\endgroup$
    – ratchet freak
    Commented Oct 1, 2014 at 21:03
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    $\begingroup$ @TylerDurden Ah, ok; Are there statistics about how often dumping passengers does actually occur? ;) $\endgroup$
    – Volker Siegel
    Commented Feb 26, 2015 at 18:12

2 Answers 2

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These two reports cite that the US Air Force at one time jettisoned fuel nearly 1000 times per year. The second report also mentions that commercial airlines reported 485 instances of fuel jettison over a 5 year period. The commercial reports are only for maintenance related cases though, not including scheduling or weather reasons.

Both of these figures date from the 1970s. Military standards have been changed since then to reduce the frequency of it. The first paper assumed that in 1995, military fuel jettisoning was "infrequent".

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In commercial aviation fuel is dumped rarely. Only if the aircraft is taking off above max landing weight and an emergency takes place shortly after takeoff would a commercial aircraft be required to dump fuel.

Military cargo aircraft have max landing weights similar to their max takeoff weights, so they also rarely dump fuel. Military tanker aircraft are probably the most likely to dump fuel as their max takeoff weight is well above their max landing weight. In this case, two scenarios would drive dumped fuel - 1) An emergency condition that will require the aircraft to land prematurely within the first couple hours of flight 2) the loss of receiver aircraft driving a condition where it would be more efficient to dump fuel and land rather than fly until the fuel is low enough. This probably occurs once a week. I'd probably estimate that all of commercial aviation dumps about as much as the US tanker fleet, but that is just a wag.

Regarding the fuel clouds, the altitudes where fuel is intentionaly dumped are high enough so that the fuel quickly disperses and is not an environmental factor. Furthermore, there are prescribed dump locations which are located away from populated areas.

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    $\begingroup$ OP knows the fuel dumping happens "rarely," and (I believe) was looking for some numbers. Do you have any specific numbers about how often fuel dumping happens? $\endgroup$
    – raptortech97
    Commented Oct 2, 2014 at 20:04
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    $\begingroup$ You need to add an "and the aircraft is capable of it" — it might be ideally required to, but be unable to. $\endgroup$
    – gsnedders
    Commented Oct 3, 2014 at 18:45
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    $\begingroup$ In my experience as an EC-121 crewman in the late 1970s (Lockheed Constellations) we dumped fuel fairly often (3 times on my own missions) due to the tendency of these older piston engine aircraft to blow out one of them on takeoff. These aircraft carried a large fuel load as well as electronics and other equipment. $\endgroup$
    – Jeff D.
    Commented Aug 14, 2017 at 18:30
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    $\begingroup$ Whether or not dumped fuel is an environmental factor seems debatable. $\endgroup$
    – rclocher3
    Commented May 16, 2019 at 18:40

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