Friday, September 30, 2011

Piper PA-31T Cheyenne, D&R Henderson Pty Ltd, VH-TNP: 34 km SE Benalla, Aero., VIC - Australia

AO-2008-050: Controlled Flight into Terrain - Piper PA31T, VH-TNP, near Benalla, Victoria, 28 July 2004 

 On 28 July 2004, a Piper PA-31T Cheyenne, VH-TNP, with one pilot and five passengers, on a private, instrument flight rules flight from Bankstown to Benalla, collided with terrain 34 km south-east of Benalla. All occupants were fatally injured and the aircraft was destroyed by impact forces and fire. Instrument meteorological conditions existed at the time and the pilot had reported commencing a Global Positioning System (GPS) non-precision approach (NPA) to Benalla.

The experienced pilot was familiar with the aircraft and its navigation and autoflight systems. The flight did not follow the usual route to Benalla, but diverted south along the coast before tracking to the northernmost initial approach waypoint BLAED of the Benalla Runway 26L GPS NPA. While tracking to BLAED the aircraft diverged left of track, without the pilot being aware of the error. The air traffic control Route Adherence Monitoring (RAM) system triggered alerts, but controllers believed the aircraft was tracking to a different waypoint and did not question the pilot about the aircraft's position. The destruction of the aircraft navigation and flight control systems did not permit verification of their operational status. The investigation found that instructions to controllers relating to RAM alerts could be ambiguous. Actions were taken by Airservices Australia to enhance alerts and clarify controllers' responses to them.

The occurrence drew pilots' attention to the need to pay careful attention to the use of automated flight and navigation systems and also demonstrated the need for effective communication between controllers and pilots to clarify any apparent tracking anomalies. The Australian Transport Safety Bureau's (ATSB) final report was released on 7 February 2006.

In July 2008, during the subsequent coronial inquest, additional information about the possibility of dead reckoning navigation by the GPS receiver was provided. The ATSB investigation was reopened to examine that possibility and an amended report issued. That investigation found that dead reckoning navigation could not be positively established as there were inconsistencies between dead reckoning principles and the recorded radar data. Neither could it reconcile how a pilot would continue navigation by GPS with the alerts and warnings provided by the GPS receiver and the instrument indications. As a result of the reopened investigation, the ATSB issued a safety advisory notice alerting users of GPS navigation receivers to take appropriate action to ensure familiarity with dead-reckoning operation and any associated receiver-generated warning messages.

A VICTORIAN coroner has found a malfunctioning global positioning system led a pilot off course ahead of a 2004 plane crash near Benalla that killed all six people on board.

Benalla timber company D&R Henderson’s executive Robert Henderson, his daughter Jackie, her husband Alan Stark and their friends Belinda Andrews and Geoff Brockie were killed when the twin-engined Piper Cheyenne slammed into a tree-covered ridge at Myrrhee in bad weather.

The pilot, Kerry Endicott, was also killed in the July 28, 2004 crash.

He had flown the Sydney-to-Benalla route weekly since 1988.

The inquest had previously heard the GPS had moved into “dead reckoning mode” for an unknown reason by the time Mr Endicott had announced his approach to Benalla Airport at 10.45am.

Coroner Paresa Spanos found Mr Endicott had been flying in cloud with no visual cues that he was flying off track and/or into terrain.

Ms Spanos said he had begun an approach relying on GPS and no land-based navigational aids.

“It is reasonable to infer that he believed that operations were normal and that in ‘scanning’ the array of instruments before him he focused on information from the GPS unit,” she said.

“Taking all evidence before me into account, I find that the accident which took the lives of all six deceased was caused by navigation with the GPS in dead reckoning mode.”

Ms Spanos also found Mr Endicott was not made aware of two previous alerts activated with air traffic controllers that the aircraft had deviated from its planned flight path.

Instead the inquest heard an air traffic controller had twice rerouted the plane from its current position without communicating with Mr Endicott about his track deviation, believing he had chosen a different approach to the Benalla airport.

“In doing so, he contributed to the accident as there was a lost opportunity for avoidance of the accident,” Ms Spanos said.

She said evidence regarding Mr Endicott’s cardiac history did not support a finding that any existing coronary condition, heart disease or any other disease in Mr Endicott, had either caused or contributed to his death or the accident.

“While the possibility of a causally relevant cardiac episode cannot be entirely excluded, it is a mere possibility, given other circumstantial evidence,” she said.