FUEL JETTISON PROCEDURE (also known as FUEL DUMPING)

I saw video and comments of the Ethiopian airline dumping fuel while making an emergency landing back to MMIA, Lagos. Many Nigerians said it is because the pilot concluded they will crash. Lol. Folks, that is not the reason.

For better understanding about fuel dumping, let's briefly talk about basic Airplane Weights.

1. Dry Operating Weight (DOW) - Weight of the airplane without passengers, cargo, and BLOCK (Trip, Contingency, Alternate, Taxi, Final Reserve) Fuel.

2. Payload = Weight of passengers + Cargo

3. Zero Fuel Weight (ZFW) = DOW + Payload.

4. Take Off Weight (TOW) = ZFW + BLOCK FUEL.

To avoid structural damages to the air frame and landing gear, Landing Weight (LW) must always be less than the TOW, and in order to do this, the pilot must either use his "Trip fuel" or dump the fuel. (Every airplane has Maximum TOW and Maximum LW).

So, when pilots declare an emergency, as is the case of the Ethiopian airline, it means they have to land at the nearest airport to their current position. It also means they will not be using the "TRIP FUEL" again, meaning they MUST dump fuel to reduce the weight of the airplane before landing. THIS IS EXACTLY WHAT HAPPENED TO THE ETHIOPIAN AIRLINE.

More Landing Weight means more landing speed, increase in the stop margin which may lead to potential runway overrun, and more airport charges. Pilots try to avoid these things.

NOTE: There are calculations to all these, to determine how long the nozzles will be opened and quantity of fuel to be dumped, because you have to put the airplane's Fuel Burn Rate into consideration too.

Planes like Boeing 737 and Airbus A320 are not fitted with the fuel dump nozzle, so in their case, they fly what is known as "HOLDING PATTERN" so that they burn some of the fuel before landing.
(If you are a frequent flyer, you must have noticed a situation where the plane is just circling the airport for minutes before landing. Yes, that is a Holding pattern). Other factors can make a plane to be in "Hold" too (I may talk on this if this post hits front page).

Also there are exceptional cases where pilots land the plane with MLW (not the essence of this post).

So, next time you see those "white stuffs" from a plane's wing tips, it means the pilot is dumping fuel. When it is from the rear of the engines, it is definitely a CONTRAIL (a whole new topic).

So Nigerians, the Ethiopian airline pilot didn't conclude the plane will crash and started dumping fuel grin grin

NOTE: This explanation here is very basic, there is more to it.

IS THERE ANY AVIATION SECTION ON NAIRALAND?

Insightful. Thanks

Nice topic,
More of this, with time, Nigerians will appreciate

This is really interesting

You have done a wonderful job here.
Endeavour to shed more light on CONTRAILs, HOLDING PATTERN and others for the benefit of those who were not in the know of basic flight info before now.

Great topic