Why would a plane have to dump fuel prior to making an emergency landing?
Posted by Methadoneblues@reddit | aviation | View on Reddit | 29 comments
I was just reading a post about a flight where a woman went into labor, so the pilot had to make an emergency landing which required him to dump some fuel prior to landing. Why is this necessary?
HokieAero@reddit
I think the correct answer is they don't HAVE TO - if it is necessary to land ASAP for medical emergencies or other reasons. But there are potential repercussions afterwards, like an inspection (if it was a nice landing) or repairs if not a nice landing. If they have time, they will likely dump fuel (but not over urban areas).
Old-Car-9962@reddit
But very pregnant people probably shouldn't fly anyway, for health risks and.. yk, HAVING YOUR CHILD ONBOARD
Old-Car-9962@reddit
It is too heavy otherwise
WarwolfAlpha64@reddit
I knew a KC-135 pilot who took off for a mission and thier gear wouldnt retract. They had to dump a full load of fuel, around 200,000lbs or 90,000kg, and land as an emergency. The problem was "fixed" that night, they flew the same aircraft the next day, and wouldnt you know it, same problem. Gear stuck down(better than stuck up to be sure), same fix action. Dump the transfer tanks and land as light as possible.
Methadoneblues@reddit (OP)
Jesus, that's unlucky! Did they ever figure out the cause?
WarwolfAlpha64@reddit
As I understand it, it an actuator was stuck so one of the gear couldnt unlock.
Somhlth@reddit
The aircraft has substantial weight with a full load of fuel. If it lands with that full load of fuel, it requires more runway to do so, and that could be problematic, depending on the emergency site the pilot is forced to land at.
Methadoneblues@reddit (OP)
Oh, wow, that's wild they carry enough fuel to increase the kinetic energy that much. Thanks for the answer!
Positive-Goose-3293@reddit
For a 747-8 you're talking up to 63,000 gallons (238,000 liters) of fuel.
Fuel weighs 6.7 lbs per gallon (0.803 kgs/liter) at room temperature.
Methadoneblues@reddit (OP)
That's insane.
Nun-Taken@reddit
Insane? No. Physics? Yes.
Methadoneblues@reddit (OP)
I'm referring to the amount of fuel. I wonder how many Olympic swimming pools could be filled with one day of worldwide plane fuel use.
rhit06@reddit
Big ships burn through a ton too. Something like a WWII Iowa class battleship carried ~19,000,000 lbs of fuel oil with a range of ~18,000 miles. So there you're burning 1000+lbs of fuel per mile.
Methadoneblues@reddit (OP)
That’s hard to even fathom. It’s incredible to me our planet hasn’t ran out of oil by now when you see the numbers.
rhit06@reddit
Each time they fired all 9 main guns the ship also would get ~30,000 lbs lighter (2700lbs/shell + 660lbs powder/shell)*9 = 30,240 lbs lighter in essentially the blink of an eye.
Big things are big.
Methadoneblues@reddit (OP)
Wow, that’s impressive. So many little things I’ve never even considered.
Methadoneblues@reddit (OP)
I'm referring to the amount of fuel. I wonder how many Olympic swimming pools could be filled with one day of worldwide plane fuel use.
Positive-Goose-3293@reddit
Yep.
A 747-8 freighter can fly 100,000 kilos of cargo from Santiago to Miami using 100,000 kilos of fuel.
fly-guy@reddit
Besides this, there are structural limits too. Think extra stress on wings, landing gear, brakes, etc.
However not all aircraft have to and can dump fuel.
Methadoneblues@reddit (OP)
How does it stress the wings, out of curiosity?
Tri-Hero11@reddit
Fuel is often stored within the wings on commercial aircraft I believe
fly-guy@reddit
Correct, in multiple separate tanks. Could be the total amount is just to much, or an amount in a certain tank can't be too much.
Impossible_Agency992@reddit
Not trying to be rude…but if you Google the exact title of your post, the AI gives a lengthy explanation.
Impossible_Agency992@reddit
Not trying to be rude…but if you Google the exact title of your post, the AI gives a lengthy explanation.
Methadoneblues@reddit (OP)
My bad. Sometimes, I forget Google exists. Plus, it's more pleasant to communicate and socialize with others.
Impossible_Agency992@reddit
That’s also fair. You can get a more in depth answer here too probably.
FudgeFront7418@reddit
Over max landing weight, land gear could collapse
adjust_your_set@reddit
Maximum Landing Weight is usually (always?) lower than Maximum Takeoff Weight. The suspension needs to absorb and arrest the downward motion on landing which isn’t needed on takeoff.
shikkonin@reddit
Aircraft can take off a lot heavier than they can land. Fuel is heavy.