What happened
On the afternoon of July 1, 1997, a near-collision occurred approximately five nautical miles south of Hamilton Aerodrome. The incident involved an RNZAF Airtrainer and an Eagle Air Metroliner traveling in opposite directions. The sequence began when the Metroliner initiated a missed approach procedure to simulate an engine failure. Following this, the Metroliner turned back toward the VOR, acting as though it could not clear the terrain to the south. Meanwhile, the Airtrainer departed Hamilton Aerodrome, following the path of the Metroliner. As the Metroliner moved into an area lacking radar coverage, the distance between the two aircraft closed. The radar returns eventually merged, indicating the aircraft were on opposite headings at the same altitude. The pilot of the Metroliner provided visual separation as the aircraft passed one another.
The investigation
The investigation examined the radar control procedures and the communication between the pilots and air traffic control. Investigators found that the standard procedures for radar control were followed correctly and no deficiencies were found in the established protocols. However, the inquiry focused on the operational intentions of the aircraft involved, specifically looking at the coordination between a Flight Testing Officer and a commercial pilot participating in a test flight.
Findings
While radar protocols were maintained, the investigation identified significant misunderstandings between the Flight Testing Officer and the commercial pilot regarding the flight test parameters. Additionally, the inquiry noted concerns regarding Air Traffic Control communication habits, specifically the tendency for controllers to acknowledge transmissions with "Roger" without fully processing the preceding information. The investigation also highlighted a lack of clarity regarding how certain information in the New Zealand Aeronically Information Publication was understood by the airline.
Safety action
- The investigation identified the need for Air Traffic Control Officers to remain fully alert to the content of transmissions before providing acknowledgments.
- There was a noted need for better alignment between airline operations and the information provided in the New Zealand Aeronautical Information Publication.