John Cox| Special to USA TODAY
Why would pilots dump fuel before landing the airplane?
– Bthornton, Kingsport, Tennessee
Airplanes frequently depart the airport heavier than the maximum landing weight allowed – the threshold at which a given aircraft can sustain a very hard landing without damage.During a normal flight, theplan is to burn fuel so the plane's weight will below that number by the time it lands.
However, if an airplane encounters a technical problem or passenger medical issue and needs to make an emergency landing early in a flight, they won't have had a chance to burn enough fuel toreduce the weight below the maximum.This means the flight crew has to quickly get rid of excess weight and the easiest way to do that is by dumping fuel.
That was the course of action chosen by the pilots of Delta Flight 89 on Tuesday after engine problemsforced them to make an emergency landing back at Los Angeles International Airportmoments after the wide-body Boeing 777 took off forShanghai loaded with fuel for the long-haul journey.
Delta fuel dump: Jet dumps fuel over schools before emergency landing, injuring 44
A captain has three choices when having to land quickly and overweight:Fly around long enough to burn the fuel down to the maximum landing weight, land with the plane still overweight or dump fuel. Depending on the situation, each option may be appropriate.
As an example, if the crew were fighting a fire onboard and struggling to do so,then landing quickly –even if overweight– would definitely be the best choice. On the other hand, a hydraulic problem would not necessarily require an immediate landing, giving the pilots time to burn or dump fuel.
Some airplanes –usually larger ones– have the capability to dump fuel to reduce the landing weight. Dumping fuel can reduce the weight quickly, dumping thousands of pounds in a few minutes.
FAA: Delta pilots didn't seek permission before dumping fuel that rained on school kids
In the rare instances where dumping fuelbecomes necessary, there are procedures that are supposed to be followed.Air traffic controllers also advisethe pilots of the closestappropriate fuel dumping area, where there are fewer people. And pilots are trained to climb to a higher altitude, which allows theatomized fuel to evaporate before it reaches the ground.
The FAA said that the Delta pilots did not request permission from air traffic controllersbeforetheir fuel dump over Los Angeles, nor did they do it at the optimal altitude. As a result, dozens of children on a nearby school playground were treated for eye and skin irritation.
The FAA says it's investigating the circ*mstances that led tothatfuel dump.
