Tailstrike

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Animation of a tail strike on landing.

A tailstrike ( English tail "tail", "tail" and strike "blow", "impact") describes the unwanted touching of the runway by the rear of the aircraft. This can happen when the pilot at the start hoisting the machine too steep and the aircraft achieved almost lifting off too much angle. When landing , the tail of the aircraft can also hit the ground if the pilot pulls the elevator too hard just before touching down, thus lifting the nose of the aircraft too much. The longer the fuselage of the aircraft, the higher the risk of a tailstrike. At a given height of the landing gear, this ultimately limits the length of an aircraft fuselage.

As part of approval and stress tests ( VMU test and TOP test ), tail strikes are deliberately induced, for example to determine the lowest possible take-off speed of an aircraft at the maximum angle of attack.

Avoiding a tail strike

De Havilland DHC-8 with a heavily sloping tail to avoid tail strikes
A DC-9-83 from Turkish Ankair touches down improperly with the tail spur during take-off

Various systems are used in modern aircraft to avoid tail strikes.

  • The manufacturer specifies the maximum angle of attack for each type of aircraft. The pilot must comply with this.
  • As can be clearly seen on the De Havilland DHC-8 in the adjacent picture, commercial aircraft have a strong bevel at the tail. This is to enable the aircraft to have a greater angle of attack. The Dash can take off, for example, at an angle of 7 °. Some types of aircraft have a permitted angle of attack of only 3 °.
  • There are also some mechanical and electronic methods to avoid tail strikes, or at least to minimize their impact on the aircraft:
    1. A mechanical example, the tail skid ( tailbumper ). As with the Airbus family, this is either a metal reinforcement of the underside of the fuselage on the tail cone; around a small additional wheel attached to the stern like on the Concorde or around a retractable tailskid like on the Boeing 777-300 .
    2. Electronic device: the Boeing 777-200 measures both the distance between the rear of the fuselage and the runway and the speed at which it is approaching the ground. A computer automatically activates the elevator when the specified limit values ​​are exceeded, thereby reducing an excessively large angle of attack. With this, a tail strike cannot be completely avoided, but it can be weakened (see web links).

Tailstrike and airplane accidents

Improper repair of tailstrikes led to two serious aircraft accidents in 1985 and 2002 - those on Japan Airlines Flight 123 and China Airlines Flight 611 . In both cases, the weakened fuselage structure could no longer withstand the pressure inside the cabin and led to explosive decompression . The accident of 1985 is to date, in terms of the number of fatalities, the worst aircraft accident in which a single aircraft was affected.

literature

Web links

Spotter recordings of tail strikes: