NB: The following is a brief plain English summary of key points in the final report from TAIC. You can download the full document at www.taic.org.nz/inquiry/ao-2023-001.
In brief:
- At Queenstown Airport's uncontrolled South Apron: 2 helicopters came into potential conflict due to contrasting mental models, confusion over who is doing what, congested airspace.
- CAA and others are working to address safety issue, so no recommendation.
- Key audiences: Aerodrome operators and planners, air traffic control personnel, helicopter company operators and pilots may all benefit from this report.
What happened
Two helicopters departing Queenstown Airport came into potential conflict because the helicopter that was meant to depart second, departed first.
- Setting: a fine and calm day at Queenstown aerodrome's southern apron general aviation movement area.
Setup: Two helicopters - an EC130, ZK-IUP (IUP) and an AS350, ZK-IDB (IDB) – were cleared to take off and depart -- IUP first and IDB second. - Event: IDB passed above and to the left of IUP and took the lead out of the southern apron. Both flights continued uneventfully.
Photo across Queenstown Airport's Southern Apron with the two helicopters airborne in the middle distance
Why it happened
A combination of contrasting mental models of the situation, confusion over who was doing what, and congestion of the Southern Apron airspace made this incident more likely.
- Contrasting mental models: IDB was initially facing away from IUP and a large building obscured IUP's helipad. IDB's pilot assumed but did not visually confirm that IUP had already departed.
- Confused movements: During manoeuvring, the helicopters came within 44 metres of each other. IUP's pilot reported that IDB took evasive action, but the Commission found that IDB was making a standard turn.
- Congestion: At Queenstown Aerodrome all helicopters are required to arrive and depart via a particular waypoint; this creates congestion and visibility issues.
Safety issue and safety actions
At Queenstown Airport's Southern Apron, conflicts and collisions between uncontrolled aircraft are more likely because of the combination of the apron layout and management of aircraft flying into controlled airspace.
There was no need for a new TAIC recommendation because the Civil Aviation Authority, Airways, and other stakeholders are already working together to address this safety issue:
- Safer procedure for departure sequencing: in new procedures, pilots are only cleared to depart if they report seeing the preceding aircraft in the departure sequence.
- Air traffic control: TAIC understands a full air traffic control service is under consideration for helicopters operating in the currently uncontrolled southern apron area.
Avoiding similar incidents in future
Complex and restrictive operating environments can impact a pilot’s ability to build an accurate mental model.
Onboard helicopter recording systems provide valuable assistance to safety investigations.
Aerodrome layout and aircraft movements need to be assessed regularly for safety of operations, especially when daily aircraft movement rates increase.