Description

On 26 July 1999, an ATR 72-200 being operated by Mount Cook Airlines on a scheduled passenger flight from Christchurch to Queenstown entered the destination CTR without the required ATC clearance after earlier cancelling Instrument Flight Rules (IFR) and in marginal day Visual Meteorological Conditions (VMC) due to snow showers, separation was then lost against a Boeing 737-200 being operated IFR by Air New Zealand on a scheduled passenger flight from Auckland to Queenstown which was manoeuvring visually (circling) after making an offset VOR/DME approach in accordance with a valid ATC clearance.

Investigation

An Investigation was carried out by the New Zealand Transport Accident Investigation Commission (TAIC). An annotated terrain chart taken from the official report is shown below to aid an understanding of the conflict which occurred.

It was established that the ATR 72 had cancelled IFR and descended below controlled airspace in order to remain in VMC and was tracking via the Kawarau Gorge at low-level. Before entering the gorge, the ATR 72 had been advised by ATC of a possible requirement to hold at the Bungy Bridge VRP on the edge of the CTR but having committed to fly through the gorge in deteriorating weather, the ATR 72 was then unable to hold at the reporting point when instructed to do so and advised their alternative intention. They subsequently stated that they had continued through the gorge visually in the belief that they did not need to obtain an entry clearance into the CTR.