What happened
On the evening of 7 January 2005, two aircraft flying under instrument flight rules (IFR) came into dangerously close proximity approximately 10 nautical miles south of Taupo Aerodrome. The first aircraft, a Gulfstream G-IV registered ZK-KFB, was operating a charter flight with two pilots, a flight attendant, and five passengers. The second aircraft, a Piper PA 28 registered ZK-FTR, was conducting a training flight with a pilot and one passenger.
Both aircraft were operating in uncontrolled airspace while performing different instrument approaches to the same aerodrome. As the Piper PA 28 descended through the altitude of the Gulfstream G-IV, the distance between the two planes closed to within one nautical mile. The crew of the ZK-KFB received traffic alerts from their Traffic Alert and Collision Avoidance System (TCAS), which indicated a proximate threat. To ensure safety, the Gulfstream G-I crew abandoned their planned instrument approach and transitioned to a visual approach to land.
The investigation
The investigation examined the flight paths, radio communications, and the use of TCAS technology. It was established that while the pilot of the ZK-FTR was aware of the ZK-KFB and had maintained visual contact, he did not communicate his intentions clearly or maintain adequate vertical separation. The investigation also noted that the ZK-KFB crew had difficulty identifying the exact position of the Piper PA 28 due to the pilot's accent and a lack of direct communication between the two cockpits.
Furthermore, the investigation found that the ZK-KFB crew had consulted the wrong approach chart, which led them to believe the ZK-FTR was approaching from the north rather than the south. This confusion, combined with the fact that the aircraft were in uncontrolled airspace, contributed to the breakdown in situational awareness.
Findings
- The incident occurred in uncontrolled airspace, where the responsibility for maintaining separation rested with the pilots.
- The flight paths of the two instrument approaches intersected, creating a high potential for conflict.
- The pilot of the ZK-FTR descended through the altitude of the ZK-KFB because he mistakenly believed he had sufficient separation.
- The pilot of the ZK-FTR failed to maintain a 1,000-foot vertical buffer above the lower aircraft.
- Communication difficulties, including the pilot's accent, hindered the ability of the ZK-KFB crew to understand the other aircraft's position.
- The incident could have been prevented if the pilots had established direct communication to coordinate their movements.
Safety action
Following the investigation, a safety recommendation was made to the Director of Civil Aviation to publish educational materials. These materials were intended to remind IFR pilots of their responsibility to mutually coordinate and maintain proper separation when operating in uncontrolled airspace, particularly when approaching the same aerodrome.