An incident in which a King Air pilot encountered instrument failure and control issues over Western Australia is a reminder of the value of aircraft system knowledge and pilot operating handbook familiarity, an ATSB final report notes.
On 25 January 2024, the twin turboprop King Air C90A aircraft departed Kalgoorlie-Boulder Airport for a charter flight to Warburton, with one pilot and two passengers on board.
About half an hour into the flight, operating in instrument meteorological conditions, the pilot was cleared by air traffic control to divert left of track to avoid a storm.
With the autopilot in heading mode, the pilot used the heading bug on the horizontal situation indicator to track left. Once past the storm, the pilot changed the heading setting to the right, to re-intercept the original track.
"Unknown to the pilot, the aircraft's remote gyroscope had failed, resulting in erroneous indications on the horizontal situation indicator," Director Transport Safety Stuart Macleod said.
This resulted in a sustained, uncommanded right turn.
Observing the aircraft continue to turn right through the selected heading, the pilot disengaged the autopilot and hand-flew the aircraft onto the correct heading.
During the manoeuvring, altitude variations between -400 ft and +900 ft were recorded on ADS‑B tracking services.
Having observed the aircraft deviate laterally and vertically, the monitoring air traffic controller queried the pilot's intentions several times.
"The combination of manually flying in instrument meteorological conditions, troubleshooting and interactions from ATC resulted in a high workload situation for the pilot," Mr Macleod observed.
A short time later, contrary to the pilot operating handbook, the pilot re-engaged the autopilot in heading mode, and made continual left inputs to the heading bug to keep the aircraft tracking left.
"This contributed to high workload and sustained control issues," Mr Macleod said.
"Additionally, the pilot not making a PAN PAN broadcast to ATC reduced the opportunity for the controller to provide appropriate assistance."
The pilot elected to return to Kalgoorlie, and landed without incident.
The ATSB's final report notes the occurrence highlights the value of aircraft system knowledge and pilot operating handbook familiarity in resolving malfunctions.
"This incident emphasises the importance of pilots utilising all options to reduce their workload, including requesting assistance from air traffic services when they recognise an emergency situation developing," Mr Macleod said.
"Controllers are also reminded that a pilot in difficulty may not immediately alert air traffic services if they are disoriented or focused on flying the aircraft. If a controller assesses they may be able to assist, this should be communicated proactively."
