Fuel dumping - AF 562 - Boeing 777-228(ER)

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Thel_Odan@reddit

Does the fuel essentially like vaporize (or whatever the word is) before it hits the ground, or do they do this over water? I honestly don't know.

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qalpi@reddit

Sometimes you can just do it over a school

https://www.cnn.com/2020/01/14/us/jet-fuel-dump-elementary-school-trnd?cid=ios_app

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cheetuzz@reddit

I still cannot fathom what those Delta pilots were thinking. Were they that ignorant? Or thought they could get away with it?

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Zn_Saucier@reddit

Delta’s press release on the incident

/s

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jet-setting@reddit

Bit of both. Over water is ideal but the fuel will atomize and basically dissolve into the air within just a couple thousand feet.

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No-Hovercraft-455@reddit

My dumb ass didn't know passenger aircrafts could dumb fuel. Thanks for sharing

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FlyRvR@reddit

He’s deciding not to go with the ER designation this time.

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inphosys@reddit

Flights these days, always cutting the ride short because some passenger is being a shining example of less than stellar behavior.

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Total_Wrongdoer_1535@reddit

I assume it’s a financial disaster for the airline. I’m glad that planes still land due to medical emergencies

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Any Airline on par with Air France in size/scale is cutting some good deals with fuel supplier and getting it cheaper than you might think. At the end of the day a few thousand tons of fuel is a lot cheaper than risking damaging the landing gear with an overweight landing.

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Robots_Never_Die@reddit

a few thousand tons of fuel

That's a big plane.

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Yummy_Crayons91@reddit

A Few thousand Pounds*

Lol that would be a big plane indeed

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inphosys@reddit

1 gallon of Jet A fuel weighs 6.7 US pounds. So, 1 ton of fuel is equal to approximately 300 gallons.

The fuel capacity of a Boeing 777-228(ER) is a little over 150 US tons.

I can't speak for how much fuel is jettison on an average fuel dump, but the published specs that I was able to find say that using only the wing (main) tank pumps, the rate is approximately 3,100 lbs per minute, or, 460 gallons per minute.

Count the minutes, calculate the cha-ching.

Oh, one thing I do know... The system is designed to automatically stop the jettison process once the aircraft reaches its maximum landing weight (MLW) fuel load, which is necessary for a safe landing.

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eliminate1337@reddit

Losing one flight worth of fuel is unfortunate but not a financial disaster

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inphosys@reddit

Plus, go Google where Delta airline makes a decent amount of coin when they're not shuttling butts in seats. Trading oil / fuel futures! The last time I remember reading about this, I think it was 2014 when trading / hedging oil futures paid all of Delta's employees a nice bonus and helped to drive ticket prices down. All because a futures hedge paid off in Delta's favor.

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StandardDeluxe3000@reddit

you could fuel fuel the heater in your house for 20 years with that.

(average house 2000 - 3000 liters per year, fuel droping by plane 25-50 tons, in emergencies up to 100 tons)

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ProfessionalOk4300@reddit

Jet A is a lot more expensive than furnace oil too

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inphosys@reddit

Could you imagine the efficiency of that furnace with kerosene / fuel oil as clean as Jet A? Retrofit the furnace with more efficient nozzles and hang on, this house is cleared for takeoff!

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inphosys@reddit

So averaging your average...

average house 2,500 liters per year which weighs approximately 2,000 kilograms (4,400 pounds or 2.2 US tons). So, by your estimate, one non-emergency fuel dump could heat between 12 and 20 homes for 1 year. Or, as you said, one home for 20 years (if Jet A stays good in a tank for 20 years). Either way, your reddit calculations are surprisingly accurate!

I'm not a bot, I'm a human, but I math.

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octoreadit@reddit

Hey, next time anyone needs to dump it, let me know, I’ll come get it, reverse-tanker style. Thanks!

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integrity0727@reddit

Try 29000 lbs fully loaded

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ChocolateSensitive97@reddit

Thank you all for the educational replies...TIL there's a limit for takeoff and a limit for landing as well! I always thought we could come right back down.

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Kunosion@reddit

Some planes can land at max weight, some can't

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swordfish45@reddit

Landing over max landing weight can happen if necessary, it will require overweight landing inspection before return to service.

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ChocolateSensitive97@reddit

But why??

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meesersloth@reddit

Fuel is heavy, the 777 and other aircraft have landing weight restrictions. So they dump fuel to lighten up the aircraft so it can land safely without breaking the landing gear or worse.

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ChocolateSensitive97@reddit

Okay I get the weight, trying to understand what you're saying..but they couldn't take off and come right back down and land again immediately if they had a problem on initial takeoff? Would they have to dump fuel to land back at the same airport? If they left 2 minutes ago? Or is it an issue with the strength and length of the landing surface at the new airport?

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JohnnyChutzpah@reddit

If it is a critical emergency for the aircraft, they can land without dumping fuel, but it will land over the aircrafts safe landing weight limit. Meaning the landing gear, air frame, and many joints in the aircraft are at risk of being damaged or destroyed.

So if a plane suffers a serious emergency just after takeoff and has no time to dump fuel before landing, there is a high likelyhood the aircraft will be damaged, sometimes irreparably. It will have to be fully inspected to make sure no damage was done. And there is a small risk of catastrophic failure of the landing gear during touch down.

A passenger having a medical emergency is not grounds to put everyone else on the plane at risk of injury or death though. So they will dump fuel which can take 10-30 minutes before starting the approach for landing.

Basically a plane generally takes off far over its safe landing weight limit for the plane itself. It's not a problem normally because the plane is expected to burn enough fuel before landing. If it suffers a problem right after taking off, they will almost always dump fuel, unless the pilots believe the aircraft is at risk of becoming uncontrollable or is on fire.

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Known-Associate8369@reddit

Would they have to dump fuel to land back at the same airport? If they left 2 minutes ago?

Yes.

Or is it an issue with the strength and length of the landing surface at the new airport?

No, its a limitation of the structure of the aircraft - the "Maximum Landing Weight", which is often lower than the "Maximum Takeoff Weight".

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chota-kaka@reddit

u/Known-Associate8369 is right about the weight issue. But there’s another reason for dumping fuel: reducing the risk of a major fire in the event of an accident while the aircraft is landing/taxiing. The less fuel on board, the lower the chance and severity of a fire.

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DadCelo@reddit

I don't get people who downvote others for asking a question. Guess everyone here was born with all the knowledge.

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Foggl3@reddit

Probably because it was explained adequately in the first reply

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rocketshipkiwi@reddit

It’s a fair question, disappointing that people downvoted you but hey.

If a fully loaded plane took off and just after decision speed they had a problem which meant they couldn’t continue they would still fly around for a while with a faulty aircraft and dump fuel.

The weight problem is primarily the stress on the aircraft landing and its ability to stop safely with that much weight on board.

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meesersloth@reddit

The strength of the gear and potentially the surface if the plane just took off its very heavy it can circle back and land once it sheds weight also it will be harder to stop since its so heavy. On the ground you can fill it up and be fine the plane can support the weight standing there or taking off no issue. When you land the force of the weight hitting the ground at a high speed can cause damage to the gear and cause the landing gear to collapse and causing more issues.

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Klutzy-Residen@reddit

You can takeoff with more weight than you can land. So if you are past the weight that you can land with you need to dump fuel or circle around.

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define_space@reddit

yes. theyd still have to dump it

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HebetudeDuck@reddit

On 13/Nov/25, due to a medical emergency, the flight AF562 (CDG - SSA) diverted to DSS.

It was necessary dump fuel, to reduce weight before landing.

I was sitting next to the window and had a chance to register this interesting moment.

They transferred the passenger to an ambulance, but unfortunately I don't have further information about it.

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Silviecat44@reddit

Better for the environment since that fuel won’t be burned?

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SkylarMighty666@reddit

How fast can they dump the fuel? Is it being pumped out or just using vacuum to pull the fuel from the wings?

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PinkFloyden@reddit

Just found a website that says the 777 can jettison fuel at a rate of 70,000 pounds per hour. They’re also apparently designed to only be operable while in the air, to prevent accidental discharges while on the ground, but doesn’t state clearly how it works unfortunately. Idk about source reliability though.

https://www.transglobaltraining.com/boeing-777-fuel-jettison/#:~:text=Each%20jettison%20pump%20in%20the,reach%20a%20safe%20landing%20weight.

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IATA	ICAO	Name	Location
CDG	LFPG	Charles de Gaulle International Airport	Paris, Ile-de-France, France
DSS	GOBD	Blaise Diagne International Airport	Diass, M'bour, Senegal
SSA	SBSV	Deputado Luiz Eduardo Magalhaes International Airport	Salvador, Bahia, Brazil

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