Saturday, August 28, 2021

Why and how do airplanes dump fuel?

In this article we will discuss why do airplanes dump fuel? How it is performed? We will discuss if it can cause any harm to people on the ground. And do all airplanes need to dump fuel or only few airplanes require fuel dumping? We will discuss each of them one by one. So let us start!

Why do airplanes dump fuel?


The main reason behind dumping fuel (also known as fuel jettison) is to decrease weight of any aircraft below its Maximum Landing Weight, which is the weight at which a given aircraft can land without any damage. Normally the airplanes depart the airport much heavier than the maximum landing weight allowed, and the airplane burns fuel so that the plane’s weight will below that number by the time it lands.


What if there is some sudden medical emergency or the airplane faced some technical emergency and the airplane has to return to its departure airport shortly after takeoff. Now the airplane is fully loaded with fuel for its long journey, so it cannot land with that much of fuel since its weight is above the Maximum landing weight. So in such situation the pilots dump the fuel to reach that threshold weight so that the airplane can land safely without any damage.


Note that the pilot has some other options too, like burning fuel in the air, but that would take a long time. So the quickest way to lose weight of airplane is by dumping the fuel since the dumping of fuel occurs at thousands of pound per minute (which is very fast!). 

How do airplanes dump fuel?


To dump fuel from the airplanes a special nozzle is fitted to the wing of many commercial airplanes, specially, large ones. And hence the pilot can pump fuel out of the nozzle into the atmosphere whenever he/she requires.


But there are some procedures that are supposed to be followed by pilot while dumping fuel. Pilots are advised to dump fuel in the closest appropriate fuel dumping area, where there are fewer people and they are also trained to climb to a higher altitude, so that the fuel get evaporate before it reaches the ground.[

"Boeing KC-767J Fuel Dumping Nozzle" by Chihaya Sta is licensed under CC BY 4.0




According to the regulations of Federal Aviation Administration (FAA), the plane has to be at least 2,000 feet above the highest hurdle along its route, at least 8 kilometers from any other aircraft and away from populated areas and bodies of water. And there are some safety features also, to stop the fuel dump at a certain level, to make sure that there is enough fuel left to continue to landing.

Can fuel dumping cause problem for the people on ground?


The answer is No. As discussed above the pilots are trained and advised to dump fuel at a safe height above the ground and over a remote area where there are very few fuel, so it is very less likely that anyone on the ground will get affected by the fuel dumping. And in most of the cases the fuel is dumped over the sea.

Do all airplanes dump fuel?


Not every plane need to dump fuel and a large no. of planes are not even fitted with the fuel dump feature. Planes like the Boeing 737, Boeing 757, Airbus A320 and many regional airplanes do not have the fuel dumping feature and that’s because they meet the specific criteria laid out by aviation regulators showing they can land near maximum landing weight by performing some maneuvers such as flying around for a while to simply burn off the fuel. For the case of Boeing 757, its maximum takeoff weight is very close to its maximum landing weight.

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