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.
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.
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.
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.
- 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.
|Date:||13 June 1997||Investigation status:||Completed|
|Time:||2246 hours EST|
|State:||New South Wales||Occurrence type:||VFR into IMC|
|Release date:||01 November 1998||Occurrence category:||Accident|
|Report status:||Final||Highest injury level:||Fatal|
|Aircraft manufacturer||Piper Aircraft Corp|
|Type of operation||Private|
|Damage to aircraft||Destroyed|
|Departure point||Charleville, QLD|
|Departure time||1925 hours EST|
|Role||Class of licence||Hours on type||Hours total|