What happened
On the afternoon of Friday, 8 September 1995, a Cessna 208 Caravan, registration ZK-SFA, was performing an approach to land at Picton Aerodrome. During this maneuver, the pilot observed a group of four RNZAF Macchi MC 39 aircraft flying in a loose formation. These military aircraft were traveling in the opposite direction and were at a nearly identical altitude to the Caravan.
To prevent a collision, the pilot of the ZK-SFA executed immediate evasive maneuvers. Despite the close proximity, the nearest aircraft in the Macchi formation passed the Caravan at a distance of roughly 300 metres.
The investigation
The investigation focused on the flight procedures and communication protocols in place during the encounter. Investigators examined the standard operating procedures within the New Zealand Air Traffic Services (NZAIP), specifically regarding how pilots report their positions when flying visually (VFR) near aerodromes that do not have active air traffic control services. The inquiry also looked into the pre-flight planning processes used by the military formation, particularly how pilots prepare for unexpected changes in flight paths necessitated by weather conditions.
Findings
The investigation identified several contributing factors to the near-miss incident. A primary cause was the lack of clear instructions within the NZAIP regarding VFR position reporting procedures, especially for aircraft operating near the boundaries of control zones at unattended aerodromes. Additionally, the investigation noted deficiencies in pre-flight planning standards, specifically concerning how pilots plan for track diversions caused by weather.
Safety action
Following the incident, safety concerns were raised regarding the ambiguity of requirements for monitoring radio telephony (RTF) frequencies once an aircraft has received clearance through a control zone. There was also a noted need for improved preparation by formation leaders regarding flight path deviations due to meteorological changes.