View Full Version : Fuel jettisoning
If the decision to dumb fuel is made are there any restrictions to jettisoning in cruise if permission is obtained? Like over the sea on the way to an alternate airport so as not to waste time in holding. The type is a B744 where Up to 45 min may be needed to reduce to max landing weight.
Thanks in advance for your thoughts.
Kennytheking
24th Oct 2021, 05:08
Some places have specific locations. Over the sea is preferable, generally above 5000' is a requirement. Avoid jettisoning whilst descending in the hold and near thunderstorms. I don't see a problem with jettisoning in the cruise and would be the sensible option as most diversions that require jettisoning would be time critical.
FullWings
24th Oct 2021, 10:36
Having done it a few times, yes, cruise is likely best. You’re also going to be going much faster (TAS) than low level or holding, so the fuel will be better dispersed as it comes out at the same rate.
Wizofoz
25th Oct 2021, 01:24
It takes some common sense planning. The goal is to LAND at or near MLW, NOT achieve MLW at some remote location then transit to the runway. Given that the difference between MZFW and MLW can be not that much, poor planning can leave you in a low fuel state.
I did hear a lot of folk-lore about jettison in the sim- thing like "Don't descend in a hold while dumping- you'll catch up with the fuel and set it on fire", and "Don't dump if there are CBs around- a lightning strike will blow you up".
Sounded like BS and certainly wasn't backed up by any litterature, but i actually got tp train a KC 135 pilot, and they obvioulsy know a thing or two about fuel. He confirmed no such concerns were valid.
mustafagander
25th Oct 2021, 09:11
Hey Full Wings,
TAS is irrelevant, it's IAS which will disperse the cloud of fuel.
I was involved in it once and on the B744 it's quite spectacular.
back to Boeing
25th Oct 2021, 16:29
Yet items like that (dump and descend and dump near CB) have made it in to my company’s OMA. If it’s BS where has it come from. I don’t know enough to be able to say to my employer “your OMA is wrong”.
Wizofoz
25th Oct 2021, 21:33
Interesting- who is your employer?