Fuel dumping

Fuel dumping during a flight is only carried out in rare emergency situations. This may, for instance, occur if an aircraft has to land directly after take-off, e.g. due to a technical problem. With full tanks, the permitted landing weight may be exceeded. The applied load would be too high for the brakes and the under-carriage, so that the aircraft might be damaged. In such a case, fuel has to be dumped to reduce the landing weight. However, there are only few aircraft, particularly long-haul aircraft, with a permitted maximum landing weight lower than the maximum take-off weight. Only these types of aircraft have provisions for discharging kerosene.

Fuel dumping requires permission from the air traffic control authority responsible, and the regulations specified by the International Civil Aviation Organisation (ICAO) must be observed. Fuel may only be discharged over uninhibited areas, and the dumping must be carried out at a height of at least 6,000 feet (1,800 m). As a rule, the kerosene vaporises completely, and the fuel residues (less than 8 percent) disperse over a large ground surface. According to the German Air Traffic Control, some 40 cases of fuel dumping are carried out in Germany in one year.

In damp weather, there can be a visible turbulence on the aircraft wings. This wake turbulence is often seen during the landing approach and mistaken as fuel dumping, but this physical-meteorological phenomenon is simply caused by condensation.