Investigation Summary
The collision involved a New Zealand Police Aérospatiale AS 355F-1 TwinStar helicopter (ZK-HIT) and an Airwork Piper PA-28-181 Archer (ZK-ENX). The Archer was flying a southbound traffic patrol for a local radio station, while the helicopter was operating westbound. At approximately 17:34 local time, the two aircraft converged over the intersection of Queen Street and Karangahape Road. The Archer's left wing struck the helicopter's main rotor, severing the outboard 50cm of the wing and causing the helicopter's rotor system to fail. The helicopter crashed onto the Northwestern Motorway link, while the Archer's wreckage fell near Symonds Street. Post-accident analysis by the FAA conducted for the TAIC revealed significant visibility limitations. The helicopter would have been visible to the Archer pilot for about ten seconds before being obscured by the airplane's engine nose 18 seconds prior to impact. Conversely, the airplane would have been visible to the helicopter pilot for only a few seconds in the upper left corner of the windscreen. Although two police observers were in the helicopter with an unobstructed view of the Archer's approach path, they did not detect the aircraft. The investigation also noted that the low position of the sun likely hindered the Archer pilot's vision.
Final Conclusions
The Transport Accident Investigation Commission (TAIC) concluded the primary cause was the failure of both crews to see and avoid the other aircraft. A critical contributing factor was the helicopter's failure to level off at the 1,000-foot altitude typically agreed upon for police operations to provide vertical separation from the traffic patrol aircraft, which usually operated at 1,500 feet. The helicopter crew also failed to establish mutual position via radio despite operating in the same vicinity. The TAIC cited the inherent limitations of the 'see and avoid' method as a causal factor and recommended the implementation of a dedicated advisory radio frequency for the uncontrolled airspace between the Auckland and Whenuapai control zones.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
New Zealand Police Eagle — Aérospatiale AS 355F-1 TwinStar · ZK-HIT
Airwork (NZ) Ltd Traffic Patrol — Piper PA-28-181 Archer II · ZK-ENX
Systems & Failure Modes
See and Avoid
The primary method of collision avoidance in Visual Flight Rules (VFR) flight, which the TAIC identified as having inherent limitations that contributed to the accident.
Altimetry and Altitude Separation
Standard operating procedures dictated the helicopter stay at 1,000 feet and the plane at 1,500 feet; the helicopter failed to level at the agreed altitude.
Interesting Facts
- 01The collision occurred at an estimated altitude of 150 meters (approximately 500 feet) while the helicopter was climbing toward its assigned altitude.
- 02One motorist on the ground received moderate facial burns from falling debris.
- 03The Airwork Operations Manual specifically required a 500-foot vertical separation between the two types of patrols (1,000 feet for the helicopter and 1,500 feet for the plane).
- 04The helicopter's main rotor landed in Grafton Cemetery, separate from the main fuselage.
- 05The Archer pilot was the sole occupant of the airplane; three people were aboard the helicopter.
Safety Actions & Advisories
Advisory Radio Frequency
The Director of Civil Aviation promulgated a single advisory radio frequency for aircraft operating in the uncontrolled airspace between Auckland and Whenuapai Control Zones to improve situational awareness.