A video of the police anti-terrorist team sliding down ropes on to a Cook Strait ferry in a helicopter training exercise shows why passengers saw the incident as a near-disaster.
The clip shows five members of the elite Special Tactics Group sliding down from a Helipro helicopter, which then lifts back towards the trailing Westpac rescue helicopter.
The rescue helicopter banks to the left before pulling back from the approaching aircraft, piloted by Helipro's Rick Lucas.
Passengers watching can be heard talking about the move, with one calling it "really dodgy". Another says: "He didn't think he was going to come back on him, eh? He had a bit of a surprise coming back at him."
The note posted on YouTube with the video praises the rescue helicopter for "quick thinking" to avoid a crash, saying without it "a mid-air collision would have occurred". At least eight people were on the two aircraft.