Global positioning system (GPS) equipment has become the focus of the investigation by the Australian Transport Safety Bureau (ATSB) into the July crash of a Piper PA31T Cheyenne near Benalla, Victoria, in which all six occupants were killed. The aircraft was undertaking a GPS non-precision approach to Benalla when it crashed.
The ATSB has found that the aircraft diverged between 3.5¼ and 4¼ left of the intended track before it disappeared from radar. No anomalies were found in the co-ordinates downloaded on to the aircraft's navigation data card and the satellite availability was found to be adequate for a GPS non-precision approach.
The ATSB is conducting further tests of the modes and functionality of the GPS receiver type that was used on the aircraft. The damaged GPS data card has been sent to the Bureau d'Enquetes et d'Analyses in France for further analysis.
Airservices Australia, the Australian air traffic service provider, issued three route adherence monitoring alerts, indicating that the aircraft had diverged from its planned track. The controllers' response to the alerts is being investigated.
The ATSB's investigation, which is continuing, has been hampered by the fact that the aircraft was destroyed in the high-speed impact and post-impact fire.
Source: Flight International
