Controlled flight into terrain

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Controlled Flight into or toward Terrain - German  controlled flight into terrain or towards (usually short Controlled Flight into Terrain or CFIT ) - is a category of flight accidents in which a fully controllable aircraft isflownby the crew against the surface of the earth or against an obstacle . In general, the crew is not aware of the impending collision.

definition

The International Civil Aviation Commission (ICAO) and the Commercial Aviation Safety Team define CFIT as the impact or near-collision of an aircraft in flight with a surface of land, water or an obstacle without any evidence that the aircraft has previously been lost control. A CFIT can take place under instrument flight conditions (IMC) as well as under visual flight weather conditions (VMC) and also includes cases in which the pilots are subject to optical deception or limited visibility, such as brownout or whiteout .

CFIT does not apply to situations in which the crew is aware of the dangerous situation but cannot avoid the collision. This is especially the case when technical or human error or adverse weather conditions lead to the loss of control of the aircraft. In this case one speaks of Loss of Control Inflight (LOC-I).

Also not covered by the term CFIT are aircraft accidents that occur in the following situations:

frequency

Between 1946 and 1955 there was an average of 3.5 cases each year in which an airworthy, controllable passenger aircraft was flown off-road. This accumulation of CFIT accidents led to the development and introduction of the ground proximity warning system GPWS in the 1970s . By 1980, despite the sharp increase in air traffic, the risk had been reduced to around two CFITs per year.

The further development of the Enhanced Ground Proximity Warning System (EGPWS), also known as the “Terrain awareness and warning system” (TAWS), enabled the number of accidents to be reduced even further. The current aircraft position is compared with an internal terrain database so that the crew can be visually informed and, if necessary, alerted much earlier than when using the radar altimeter .

Prevention of CFIT accidents

Several strategies are used to prevent such accidents.

In instrument flight and instrument landings, minimum flight altitudes apply, which must not be fallen below. On a VOR-DME approach, for example, cockpit instruments show the correct direction of the approach, as well as the distance to the airport. On an approach chart, the crew can read off at which distance and which altitude should be maintained.

A computer-aided warning is issued on the air traffic control side if the aircraft is flying too low. However, such monitoring only takes place in the vicinity of airports and only if air traffic control is appropriately equipped.

On the aircraft side, there are various techniques that are intended to prevent CFIT accidents.

  • The radar altimeter warns if you are flying close to the ground without the flaps or landing gear extended. Far from an airport, however, it is still possible to collide with the terrain in a controlled "landing approach".
  • The above technology is supplemented by the navigation system: A warning is issued if the flaps and landing gear are extended in low flight, but there is no airport nearby.
  • The current state of the art (2010s) is EGPWS (Enhanced Ground Proximity Warning System) or TAWS (Terrain Awareness and Warning System): The warning system accesses a digital terrain database. Based on the satellite navigation , it is calculated whether the aircraft is on a collision course with the terrain. EGPWS includes the terrain, the direction of flight and the airspeed, and prompts the pilots to climb if there is a threat of a collision with the terrain within a certain time frame.

Examples of CFIT incidents

Poor vision

Incorrect perception of the position

Incorrect perception of flight altitude

Incorrect perception of the terrain

  • May 9, 2012: In the accident of a Sukhoi Superjet 100 manufactured by the manufacturer, a Superjet (RA-97004) flew on a demonstration flight over Indonesia against Mount Gunung Salak . All 45 inmates were killed. The pilots had switched off the correctly functioning EGPWS , which would have warned of the mountains. They wrongly assumed that there was no such high mountain in the vicinity (see also the Sukhoi Superjet 100 accident in Indonesia in 2012 ) .

Deliberately falling below the minimum descent altitude

  • On October 19, 1988, the pilots of a Boeing 737-200 from Indian Airlines (VT-EAH) fell below the minimum descent altitude on the approach to Ahmedabad airport in poor visibility . The machine brushed against a high-voltage pylon, crashed into a rice field, and went up in flames. Of the 135 people on board, 133 died (see also Indian Airlines flight 113 ) .

Incorrect operation of the flight management system

Web links

Individual evidence

  1. ↑ a b c d e f CAST / ICAO Common Taxonomy Team: Aviation Occurence Categories. Version 4.7, December 2017, p. 9 (PDF, English, accessed on February 14, 2019).
  2. ↑ Controlled Flight into Terrain. Flight Safety Foundation, accessed February 14, 2019.
  3. ^ Nicholas Sabatini: Downward Pressure on the Accident Rate ( Memento of April 16, 2014 in the Internet Archive ). International Society of Air Safety Investigators, Federal Aviation Administration (Speech May 12, 2006).
  4. ^ Accident report L-749 Constellation VT-CQP, November 3, 1950. Aviation Safety Network (English, accessed on August 4, 2014).
  5. ^ Accident report B-720 AP-AMH, May 20, 1965. Aviation Safety Network (English, accessed on August 17, 2017).
  6. ^ Accident report B-737-200 VT-EAH , Aviation Safety Network (English), accessed on February 22, 2019.
  7. ↑ accident report B 757-223 N651AA, 20 December 1995. Aviation Safety Network (English, accessed on February 8, 2016).