What happened
While preparing for a flight to Moorabbin Airport, the pilot of VH-LRI, an Aero Commander, undertook extensive preparation to manage the challenges of an unfamiliar aerodrome. This preparation included studying satellite imagery, consulting experienced pilots, and reviewing the En Route Supplement Australia (ERSAT). During the flight, the pilot utilized an electronic flight bag and GPS navigation to assist with the approach.
However, a failure to notice that the aerodrome reference point was distant from the runway 17R centerline, combined with a slight discrepancy between the runway's magnetic heading and its designation, resulted in a flawed navigation setup. The configured inbound track was significantly offset from the actual runway centerline. As the aircraft crossed the 17R centerline, the navigation unit indicated the aircraft was still to the right of the intended track. This led the pilot to fly through the 17R centerline and inadvertently join the final approach for runway 17L. This path placed the aircraft in close proximity to VH-EUE, a Cessna 172, which was operating in the eastern circuit.
The investigation
The investigation examined why the aircraft entered the path of the other aircraft and why the deviation was not immediately intercepted by controllers. It was determined that the pilot of VH-LRI did not identify the offset between the aerodrome reference point and the runway centerline during pre-flight planning.
Furthermore, the investigation found that air traffic control (ATC) did not advise the pilot of VH-LRI regarding the presence of VH-EUE. This was because the Cessna 172 was operating in the eastern circuit, which required a specific clearance to enter, and the aircraft lacked ADS-B out capability, making it invisible to traffic awareness systems. At the time of the deviation, both the western and eastern circuit controllers were focused on other traffic, and the deviation was only noticed once visual contact was re-established.
Findings
- The pilot's unfamiliarity with the airport led to a GPS configuration that was significantly offset from the runway centerline.
- The lack of ADS-B out on VH-EUE prevented detection by traffic awareness systems.
- ATC intervention was critical; the pilot of VH-LRI initially intended to orbit left, while the instructor on VH-EUE intended to climb. Both actions would have increased collision risks or conflicted with other traffic, but timely instructions from ATC successfully deconflicted the aircraft.