Piper Aircraft Corp PA-28R-201T, VH-RBG

Personnel information

The pilot held a private pilot licence and a current medical
certificate. His total flying experience was about 1,595 hours, of
which about 19 were in the accident aircraft. He had flown 11 hours
in the previous 30 days and about 8.5 hours on the day of the
accident.

The pilot had obtained a NVFR rating in 1981 and a command
instrument rating (single engine) in 1986. The instrument rating
expired on 31 May 1997. There was no record that the pilot had
maintained the recency requirements for these ratings. His logbook
showed 305 hours of instrument flight time. However, it was not
possible to determine his experience in flying in instrument
meteorological conditions.

Meteorological information

The pilot obtained a weather forecast for the flight at about
midday on the day of the accident. This included the forecast for
the areas between Longreach and Dubbo and the terminal forecast for
Coonamble. The forecast was for 3 octas of strato-cumulus cloud at
3,500 ft and 6 octas of alto-stratus cloud at 12,000 ft. Low cloud
(base 800 ft) and drizzle were forecast for periods of less than 30
minutes between 1600 and midnight. Fog was not forecast for the
period associated with the flight.

A cold front, including a band of middle and low-level cloud and
associated rain, cleared the Coonamble area before 2100, leaving
the sky mostly clear of cloud. Fog quickly developed in these
conditions. An expected south-westerly change did not reach
Coonamble until 0330 the following morning. Post-analysis of the
synoptic situation indicated that the cloud cleared from the
Coonamble area much earlier than expected, but was followed by the
development of localised fog.

Aerodrome and approach information

Coonamble aerodrome is 604 ft above sea level. The 1,527 m
sealed runway 05/23 was fitted with edge lighting but not approach
lighting. A grass strip 12/30 intersected the western side of
runway 05/23.

The aerodrome was served by a non-directional beacon (NDB) radio
navigation aid located approximately 500 m to the north of the
runway 23 threshold. A published instrument approach procedure
using the NDB enabled aircraft to descend from 3,500 ft to 1,200 ft
above sea level on an inbound track of 200 degrees M. At 1,200 ft
an aircraft would have been 596 ft above the aerodrome elevation.
The inbound track for the approach was 200 degrees M. If unable to
see the runway when the aircraft was over the NDB at 1,200 ft, the
procedure required that the pilot maintain a track of 200 degrees
M, and climb to 3,500 ft.

Wreckage and impact information

The initial impact occurred about 120 m from the northwestern
end of the grass runway while the aircraft was tracking 178 degrees
M. Assuming an engine speed of 2,300 RPM, propeller slash marks at
the accident site equated to an aircraft groundspeed of about 145
kts. The aircraft was descending at an angle of 5 degrees and was
banked 32 degrees left. The landing gear and flaps were retracted.
The wreckage trail extended 200 m beyond the initial impact point.
The accident was not survivable.

No fault was found with the aircraft or its systems that may
have contributed to the accident. At previous periodic inspections,
the operational category of the aircraft had been downgraded from
IFR to VFR Day. The serviceability status of the flight instruments
at the time of the accident could not be established.

Fog prevented the pilot from conducting a visual approach.
The pilot did not divert to a suitable aerodrome.
The pilot descended below the NDB approach minimum descent
altitude without establishing visual reference with the
runway.

The conduct of the flight suggests that the pilot may have been
under pressure to complete the flight to Coonamble that evening.
This was evidenced by:

The pilot's decision to continue to Coonamble rather than
remain at Charleville overnight as earlier planned, despite
receiving advice that the weather en route was not suitable for
NVFR flight;
The pilot's decision to conduct an instrument approach at
Coonamble, after deciding not to proceed to Dubbo when advised that
weather conditions there required instrument approach
procedures;
The decision to conduct an NDB approach at Coonamble after
advising flight service that he was diverting to Walgett; and
The change in flight status to IFR and the pilot's advice to
flight service that he was "IFR rated", although his instrument
rating had expired.

There was no evidence that the pilot had rested at any stage
after departing Longreach. Consequently, at the time of the
accident, he had been awake for about 17 hours, half of which was
flight time. The pilot may have been experiencing fatigue. The
effects of fatigue can include a decreased level of performance in
complex tasks, and lowering of an individual's ability to
concentrate. These effects could have contributed to the pilot
being slow to recognise, and to respond to, the aircraft's
proximity to the ground.

It is possible that the pilot descended below the minimum
altitude in an attempt to see the runway lights in order to land.
To do so would have required that he divide his attention between
flying the aircraft (by reference to the flight instruments) and
looking outside the cockpit for the runway lights. This would have
involved a high workload, and if the pilot's flight instrument scan
was not adequate, a significant loss of altitude and associated
increase in airspeed could have rapidly occurred.

The purpose of the flight was to convey two passengers from
Coonamble to Longreach and then to two properties near Barcaldine,
before returning to Coonamble. The flight departed Coonamble at
about 1615, arriving at Charleville at 1835 for an overnight
stop.

At 0619 the following morning, the aircraft taxied for Longreach
and, at 0948, taxied for Coreena Station, arriving there at 1020.
The flight subsequently continued to Barcaldine Downs Station,
where the party was offered overnight accommodation. However, this
was declined because rain, which may have affected serviceability
of the property airstrip, was expected, and one of the passengers
had commitments in Coonamble early the following day. The pilot
indicated that they would fly to Charleville and remain there
overnight. The aircraft arrived at Charleville at 1836 where a
local commercial pilot refuelled the aircraft. He discussed the
Charleville-Coonamble en-route weather with the pilot, indicating
that, in his opinion, it was not suitable for night visual flight
rules (NVFR) flight.

The aircraft departed Charleville at about 1925. The pilot
notified flight service of the NVFR flight and arranged a SARTIME
of 2150 for arrival at Coonamble. At about 2145, the aircraft was
in the Coonamble area but the pilot reported that he was unable to
see the runway lights. A pilot at the aerodrome terminal advised
him that the runway lights were on but that there was thick fog
present.

At 2204, the pilot informed flight service that he was
proceeding to Dubbo and that the aircraft's fuel endurance was 200
minutes. At 2206, flight service advised the pilot that the Dubbo
weather was not suitable for NVFR operations. At 2215, the pilot
reported that he was diverting to Walgett. He did not request from
flight service a weather forecast or report for Walgett or for any
other location.

The direct track to Walgett from the aircraft's position at that
time passed over Coonamble. The pilot reported at 2237 that he
intended to conduct an instrument approach at Coonamble. In
response to a query from flight service, the pilot confirmed that
he was "IFR rated" [instrument flight rules rated]. He commenced
the approach at about 2238. At 2239, the pilot reported that he was
conducting the initial part of the approach in visual conditions
and that he would then be in instrument flight conditions for the
remainder of the approach.

A witness at the aerodrome terminal reported that thick fog was
still present. He heard the aircraft fly low overhead before the
noise changed, as if engine power had increased. He then heard the
sound of an impact. The wreckage was located about an hour later,
immediately west of the intersection of the sealed runway and the
grass strip.