Fuel dumping

Illustration: The vapour trails that can sometimes be seen behind planes as they land are caused by condensing humidity in the air in certain weather conditions.
The vapour trails that can sometimes be seen behind planes as they land are caused by condensing humidity in the air in certain weather conditions.

You may have heard stories about aircraft dumping fuel on the approach to an airport. Is there any truth in these reports?

Owing to their special design and the size of their fuel tanks, long-haul aircraft are unable to land safely with full tanks. Because of the lightweight construction of the landing gear and brakes, the maximum touch-down weight of these aircraft is considerably lower than the take-off weight. If technical problems occur immediately after take-off, it may become necessary to reduce the weight by dumping fuel before landing. The crew must obtain permission for this process from the relevant air traffic control service. So fuel dumping is:

  • only practised in emergencies
  • only done by long-haul aircraft, which have the necessary fittings
  • happens only once per 30,000 take-offs in Germany
  • has never occurred in the Dresden region in recent years.

To dump fuel aircraft have to maintain a minimum altitude of 1,500 m, and the dumped fuel vaporises in normal weather conditions. It is therefore highly unlikely that fuel particles can be detected on the ground. This has been measured and verified.

The probability of fuel dumping happening at Dresden International Airport is extremely low, because no long-haul aircraft are scheduled to operate here. The vapour trails that can sometimes be seen behind planes as they land are caused by condensing humidity in the air in certain weather conditions.