Computer-Related Incidents with Commercial Aircraft

The T-43A Accident near Dubrovnik

3 April 1996

Synopsis A US Air Force T-43A, a military version of the Boeing B737-200, crashed into terrain while on approach to Dubrovnik airport, Croatia, in conditions close to or below the published minimums for the approach. The US military publically released the results of its investigation in June, 1996. This report is culled from published news in the professional and general press concerning the accident and the final report, with some information on USAF safety report procedures from Lt.-Col. Thomas Farrier of the USAF Office of the Chief of Safety. A short note on automation and risk citing this accident appeared in RISKS-18.08.

It transpires that the aircraft was equipped with only one ADF (Automated Direction Finder), a navigation device described as `primitive' by certain Air Force staff (see report). It seems the aircraft was not as well equipped as normal civilian standards would require, and it flew off course and hit a mountain while in the last stages of approach (a CFIT, Controlled Flight into Terrain, accident). One speculated almost immediately that more sophisticated navigation equipment would have helped avoid the accident; and immediately on publication of the report, US Defense Secretary William Perry ordered equipment changes.

One may conclude from Secretary Perry's executive order that this is an example of an accident in which lack of sophisticated avionics played a role. I conclude it is an example of the risk of not using up-to-date avionics - a lesson we may forget when thinking solely about the risks of using computers.