About a week ago, a Korean Air flight, operating a Boeing 777, experienced a problem with the left engine shortly after take-off from Dallas/Fort Worth International Airport in route to Seoul, Korea. Passengers reported hearing a large boom, and some reported a flash or fire from the affected engine. The pilot was forced to make an emergency landing.
Because the problem occurred at the start of a long flight, the plane circled over Tarrant County for approximately forty minutes in order to jettison the fuel. A fuel dump was necessary because the plane was too heavy to land. All aircraft have a maximum landing weight limitation, and landing over that weight would risk compromising the structural integrity of the aircraft.
Although jet fuel is lighter than water, it still weighs roughly 6.8 pounds per gallon. Add the weight of the fuel to the weight of the plane and its passengers and cargo, and you can’t land with a full tank, especially when you fully fueled for a fourteen-hour flight.
So what happens to the toxic fuel that is dumped? Is there an adverse impact to humans and the environment? According to DFW airport, the fuel from the airliner should dissipate before it hits the ground. This is obviously affected by the altitude of the aircraft at the time of the dump and atmospheric conditions.
For that reason, the Federal Aviation Administration enacted a fuel dumping policy that proscribes a minimum aircraft altitude and requires a minimum separation between aircraft of five miles prior to dumping. They also attempt to direct such aircraft away from populated areas and toward large bodies of water where possible.