Fuel Dumping

Fuel dumping ( German: Fuel draining ) is used to lower the weight of the aircraft under the maximum allowable landing weight before an emergency landing due to the venting of kerosene. This process represents a measure that is not permitted or provided in regular flight operations and therefore applies only before emergency and safety landings.

Alternatives

An alternative to fuel dumping is the immediate landing with a higher than allowable landing weight (English: overweight landing ), especially in medical emergencies or critical technical problems. Almost all types of aircraft are designed to land safely even to its maximum takeoff weight; following, however, costly investigations and any repairs are needed. An Airbus A380 landed for example, 2010 after an engine explosion with a weight that was 50 tons above the maximum landing weight because of Treibstoffnotablass had failed due to the damages being incurred.

General

When an aircraft with still nearly filled fuel tanks would have to land immediately after the start again, its weight would be due to the unspent fuel higher than its maximum landing weight which is less than the maximum takeoff weight (English: maximum take off weight - MTOW). Therefore, the U.S. aviation authority FAA in the 1960s adopted Regulation that all aircraft whose MTOW is above 105 percent of the maximum landing weight, a system need to Treibstoffnotablass.

Since most short-haul aircraft that limit but not exceeded, no Treibstoffnotablass system was installed in them. As this but with time got bigger tanks for greater distances, this exceeded even the 105 percent limit. However, since at the same time the engines were becoming safer and more efficient and the installation of Notablasssystemen was hardly possible, the FAA lifted the 105- percent rule for aircraft that can start and take off with one engine inoperative. Thus a Treibstoffnotablass for twin machine was not necessary. Nowadays, therefore, need only four-engine aircraft will be equipped with this system. However, many twin- large commercial aircraft can be equipped with a customer Treibstoffnotablassanlage to revolve not spend hours in an emergency need. For small aircraft today the installation of Treibstoffnotablassanlagen is not possible by design, so that there circles for hours already occurred (see also incidents at Jet Blue ).

Because nowadays most aircraft twin engine and emergencies are very rare, jettison fuel is rarely required. In Germany it thus comes to about 50 cases per year, of which about half in civil aviation. In total, about 300 tons are released, which atomize into fine droplets of about one quarter of a millimeter. Most of them to evaporate in the air, only about eight percent reach the ground, which in turn is distributed over a very large area. " Environmental impact on the ground could not yet be detected, because the fuel on the way to Earth's surface is widely distributed and evaporates. "

Regulations

For the unloading of fuel must first be an emergency situation. In consultation with the air traffic control air traffic controller then instructs the pilot under the provisions of ICAO to an area, which has a low settlement structure. The minimum flight altitude has 6000 feet ( ft) (approx. 1,850 m). While the plane discharges the kerosene, it is usually in the climb in a spiral with several kilometers in diameter.

Likelihood of confusion with extractor flags

In some cases there is the assumption that aircraft generally Drain fuel before landing to reduce by about the risk of fire. This stems mostly from the fact that at high humidity emanating from the wingtips country forming aircraft haze flags that can be kept for atomized kerosene. However, these flags haze caused only by condensing water. The overpressure at the underside and the under pressure on the upper surface of the wing at the wing tip is held a pressure balance, which in turn leads to a drop in temperature. Thus, the water vapor contained in the air can condense at suitable conditions.

Dump and Burn

During flight operations the General Dynamics F -111 of the Australian Air Force was a dump and burn (English for: draining and burning ) process called part of the demonstration program at public events. Also at the closing ceremony of the Olympic Games in Sydney in 2000 Dump and Burn was demonstrated. This exploits that is at the F -111 the Treibstoffnotablass between the engines. It will take some seconds drained fuel, while the engines are running in afterburner. The fuel is ignited by several meters and produces a long flame behind the aircraft, while you can hardly see the faint Nachbrennerflammen. After the withdrawal of the F -111 today is only the Saab Gripen in a position which, like the F -111 presents to dump and burn this on air shows.

The fuel drain devices on civil airliners are away from the hot jet exhaust of the engines mounted so that such an effect is avoided. The arm-thick about drain pipes are often located at the wing tips.