Australia’s Civil Aviation Safety Authority (CASA) says it is enhancing its operator risk assessment processes to allow it to identify more clearly operators that are a risk to aviation safety following the Australian Transport Safety Bureau’s (ATSB) final report into the July 2005 crash of a Piper PA31-350 Navajo Chieftain at a ski resort in Victoria.

The aircraft, on a charter flight from Melbourne Essendon, crashed into a tree-covered ridge, 5km (3 miles) south-east of Mount Hotham aerodrome, after the pilot flew into known extreme weather conditions and did not follow the published approach procedure (Flight International, 23-29 August 2005). The pilot and two passengers died in the crash.

The pilot proceeded with the global navigation satellite system approach despite being told he would be unable to land in the weather conditions – snow showers and unbroken cloud at 100-200ft with icing conditions – and that the aircraft was not equipped for icing conditions. Two aircraft attempting the same approach earlier had diverted to alternate aerodromes due to the conditions.

The ATSB says the conditions are conducive to visual illusions associated with a “flat line” phenomenon, whereby flat light can impair a pilot’s ability to perceive depth, distance, altitude or topographical features.

The ATSB’s investigation has confirmed that the pilot did not follow the published GNSS instrument approach, tracking via a road rather than following prescribed tracks.

The ATSB has learned that the pilot frequently used non-standard approach procedures to get clear of cloud. “This accident highlights the unsafe nature of such practices,” says the bureau.

CASA had been monitoring the operator over two years before the accident, but had not identified any significant operational issues.

Source: Flight International

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