Air Transport World

Danger on the rise: CFIT accidents increased last year, reversing an improving trend. (Safety).(controlled flight into terrain accidents analysis)

"It is better to be unsure of where you are and know it than be certain of where you are not." The famous navigator's saying is haunting the airline industry as it grapples with a resurgence of controlled flight into terrain accidents that are scarring the industry's drive for improved safety.

Last year CFIT accounted for 18 of the 40 commercial aviation hull losses, including four jets, thereby reversing an improving trend since a peak of seven jet losses in 1998. As Flight Safety Foundation President Stuart Matthews observes, "The scourge of CFIT has reappeared with a vengeance." Unfortunately, there is no simple answer as to why this has occurred.

Boeing Commercial Airplanes Chief Engineer-Aviation System Safety Paul Russell cites the reappearance of old enemies: "Distraction, loss of situational awareness, circling nonprecision approaches and failure to follow procedures."

Lack of situational (positional) awareness was a factor in all of the 219 CFIT accidents that occurred between 1980 and 1996, according to Britain's Civil Aviation Authority. Situational awareness shortfalls were compounded by the sobering fact that in 194 of those accidents the aircraft was not fitted with the latest safety equipment available at the time. Failure of CRM (154) and lack of ground aids (73) were other major circumstantial factors.

The installation of GPWS on commercial aircraft has resulted in a dramatic reduction in CFIT accidents from 1.20 per 10 million departures to just 0.35, according to Honeywell figures. But GPWS has well-understood shortcomings: It does not function when the aircraft is in landing configuration nor can it give any warning of vertical terrain. Additionally, it only provides limited warning of rapidly rising terrain.

The four jet transports involved in CFIT accidents last year were fitted with GPWS. The largest single step that could be taken to reduce CFIT risk would be to install Enhanced GPWS/Terrain Avoidance Warning Systems in every commercial aircraft before its next flight. …

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