The Australian Transport Safety Bureau (ATSB) has highlighted the impact of fatigue on pilots’ decision making, following an incident where a Cobham Aviation Services Australia British Aerospace Avro RJ85 descended below minimum altitude.
The incident occurred on 23 June, and involved the aircraft registered VH-NJW. There were five crew and 67 passengers on board, says the ATSB in its report.
The aircraft departed from Perth airport at 04:20 local time, enroute to Granny Smith airport in Western Australia. During approach, the crew received a weather report from nearby Laverton airport indicating cloud at 800ft above ground level. The crew then planned to continue to overfly the airport at 3,300ft to assess whether they would be able to obtain the required visual reference to land at Granny Smith. Failing which, it would divert to Laverton airport, with an area navigation (RNAV) approach.
Upon arriving overhead of Granny Smith, the crew found conditions to be overcast, and made the decision to divert to Laverton. The crew also advised that if they were able to establish visual reference at Laverton, they would track back to Granny Smith.
The captain then descended the aircraft to 3,100ft and configured it to land at Laverton with flaps set to 24 degrees and landing gear deployed. Around 2.5nm from the runway and at 2,150ft, while the aircraft was clear of cloud, the runway was still not visible. The captain then disconnected the autopilot and turned the flight director off to conduct a visual approach.
As the weather southwards was clear, the captain elected to divert back to Granny Smith, and with the aircraft still in landing configuration, planned a straight-in approach for runway 16. During the transit between airports, the published minimum sector altitude was 3,300ft, however the captain observed that the radio altimeter indicated the aircraft was at 500ft.
Shortly after, the EGPWS made a “Don’t Sink” warning, and in response the captain pitched the aircraft nose-up and increased thrust, climbed through cloud and levelled off clear of the cloud. A second “Don’t Sink” warning was then received, and the captain immediately initiated a go around and climbed up to 4,000ft AMSL.
Due to the additional fuel burn from having the aircraft in landing configuration, the crew decided to divert to Kalgoorlie to refuel, instead of the planned alternate of returning to Perth. While on the ground there, the captain contacted Cobham’s flight operations manager who queried whether he was fit to continue. The captain indicated that he was, and the aircraft subsequently took off and landed safely at Granny Smith. The same crew then operated the return flight back to Perth.
In its investigation, the ATSB found that the captain had only around three hours’ sleep in the preceeding 24 hours before duty, and that his decision making had been affected by the lack of sleep.
Cobham immediately issued an operational notice to all crew on operations to airfields without instrument procedures, It highlighted that crew are not permitted to conduct an approach at a nearby airfield to gain visual reference and then transit to another airfield below the lowest safe altitude.
In its safety message, the ATSB says research has shown that less than six hours’ sleep in the preceeding 24 hours “was found to be associated with degraded operational performance and increased error rates.” Thus, it reinforced that pilots must assess their fitness to fly prior to signing on for duty.
Source: Cirium Dashboard
