Torghatten og Controlled Flight Into Terrain - CFIT - Curt Lewis

Torghatten havariet var en såkalt CFIT; et fly som fungerer som det skal, men som treffer bakken eller vannet. Takket være tekniske innretninger har slike ulykker avtatt vesentlig. En person skiller seg ut som den som har bidratt til å utvikle slike tekniske innretninger, nemlig Don Bateman som var ansatt i Honeywell. Det gjelder naturligvis Ground Proximity Warning System. Ved en tilfeldighet traff jeg ham i Amsterdam. Jeg holdt er foredrag for FSF, og han var der for å motta den høyt hengende Collier Trophy på vegne av sitt firma. Her et bilde av Don og undertegnede tatt av IFALPA President Bart Bakker:

Accidents that changed aviation: Controlled flight into terrain

By: John Cox


When an airplane impacts the ground with no mechanical problems or failures and weather is not a factor, accident investigators call it a Controlled Flight Into Terrain (CFIT) accident. Once it was the leading cause of fatal accidents; now it rarely occurs. What changed?

In the 1970s and '80s, airplanes were impacting the ground at an alarming rate. Too often, airplanes with no mechanical or weather issues were involved in accidents due to the pilots not realizing where they were or becoming distracted.

In 1970, a flight carrying the Marshal University football team struck a hill while attempting to land in Huntington, W-Va. The pilots had executed their descent below the minimum descent altitude. Tragically, all aboard were fatally injured.

This type of accident happened too frequently, and pilot training focused on situational awareness was not slowing the rate. Eastern Airlines Flight 401 descended into the Everglades on Dec. 29, 1972. TWA Flight 514 flew into a mountain Dec. 1, 1974, as it approached Washington Dulles. Eastern suffered another disastrous accident in La Paz, Bolivia, on Jan. 1, 1985, when a 727 flew into Mount Illimani.

Existing Ground Proximity Warning Systems (GPWS) were not providing critical warnings, and the false-alarm rate was too high. Could GPWS be improved?

The goal was for an avionics manufacturer to develop a better system that would warn pilots of an impending collision with the ground. A few people thought it was possible; one was Don Bateman. An engineer and inventor, Bateman reasoned if accurate location information was compared with three-dimensional maps, then a computer could determine if ground impact was likely and provide warning to the pilots in time for a successful escape.

Bateman built a prototype of this warning system and testing began. As with any complex technology, updates and modification were necessary. The system matured and by the early 1990s was tested in airline-type operations.

During the night of Dec. 20, 1995, American Airlines Flight 965 approached Cali, Colombia. The pilots had complex navigation challenges and misunderstood what the flight management computer was telling them. The result was the Boeing 757 turned out of the valley and into mountainous terrain. While the onboard GPWS finally did provide a warning, it was too late. The airplane slammed into a mountainside, another CFIT accident.

Following the accident, airlines began to equip airliners with the improved GPWS known as Enhanced Ground Proximity Warning (EGPWS). The number of CFIT accidents began to decrease as the number of EGPWS "saves" increased. Bateman's system worked.

The FAA recognized the need for this safety enhancement to be mandated. In 2000, all airliners were required to install EGPWS, now called Terrain Awareness Warning System (TAWS). This technology would dramatically reduce one of the most common accident types.

Today, the rate of CFIT accidents is much lower, and most are due to airplanes in some countries not having TAWS installed. Very few TAWS-equipped aircraft are involved in this type of accident; the few that have occurred resulted from the pilots ignoring the TAWS warnings.

Pilots are trained to react immediately to a TAWS warning. The number of aircraft that have landed safely after this warning grows every year. TAWS is life-saving technology that improved aviation safety.