The pilot submitted a flight plan indicating a planned departure
from Cobar at 1500 ESuT (1400 EST). A refuelling stop was to be
conducted at Windorah. The planned arrival time at Osborne Mine was
1830 EST. Last light in the area was 1931.
The aircraft left Cobar at about 1455 EST. (The reason for the
late departure was not established.) The planned flight time to
Windorah was 2 hours 40 minutes. The aircraft was on the ground at
Windorah for about 1 hour 30 minutes, apparently because the
passengers walked to the township. Refuelling was completed at
Windorah at about 1845. The planned flight time from Windorah to
Osborne Mine was 1 hour 30 minutes. The pilot contacted the mine by
radio and reported that he would be arriving at 2030. The runway
lights were then activated by the mine staff.
A witness at the mine saw the aircraft, with navigation lights
operating, fly overhead at an estimated height of 300 ft above
ground level, considerably lower than the normal aircraft altitude.
The aircraft was visible in the glow of the lights at the mine. A
short time later, the witness was in a position to see the runway
lights, and noted that the aircraft was to the north of the runway.
He then lost sight of the aircraft as he drove the remaining
distance to the strip. Later, he reported to the mine's
communication centre that the aircraft had not landed. A formal
search was commenced at 2100 when the pilot failed to cancel his
search and rescue watch. A satellite which monitors transmissions
from emergency locator beacons detected a beacon signal at 2132,
when it passed over the accident area. The aircraft wreckage was
subsequently located about 400 metres north of the airstrip.
Wreckage examination
Examination of the wreckage indicated that the aircraft struck
the ground at a high rate of descent, and banked about 50 degrees
right. Aircraft speed at impact was estimated at about 100 kts, and
the engine was developing moderate power. No fault was found in any
aircraft system which might have contributed to the accident. The
impact was not survivable.
Pilot experience
The pilot was the holder of a private pilot's licence and a
current medical certificate. He held a Night Visual Flight Rules
rating and had accrued 30.4 hours of night flying experience. To
act as pilot in command of an aircraft under these rules it was
necessary for the pilot to satisfy a number of recent experience
requirements. These included one hour flight time at night in the
previous 12 months; one takeoff and landing at night in the
previous six months to fly without passengers; and three takeoffs
and three landings at night within the previous 90 days in order to
carry passengers in the aircraft. According to the pilot's log book
he had not met any of these criteria. His most recent night flying
had been conducted in late July 1997.
Flying conditions at Osborne
Some high cloud was present in the mine area. Visibility was
good, but the night was dark with no moon and no visual horizon.
The wind was blowing from the north-east at right angles to the
runway and about 10 to 15 kts in strength.
A parking area and lit wind sock were located on the southern
side of the airstrip near its south eastern end. The runway
lighting system contained a series of lights which pilots could use
as a glide slope indicator when landing towards the south-east.
Since the pilot had never previously landed at the airstrip during
darkness it is not known whether he was aware of this feature.