It’s just before 7:20 am when NSW Police pilot Peter Leslie climbs into the cockpit of PolAir 4 with crewmates Alan Keane and Steve Southey, to rescue a couple of ocean swimmers in trouble off Curl Curl beach.

Within minutes the men are in the air, rising quickly from their Mascot base and heading over the harbour, cutting quickly through the summer air on the short journey North.

The date is Friday 15 January 1988. A picture-perfect Sydney morning.

With nothing but blue sky stretched out before them, the officers know to expect a busy shift. Colourful beach umbrellas, towels and togs already punctuate the golden coastline, as families flock to the water to escape a forecast 28-degree day.

“The harbour beaches were all busy because people were in town for the Bicentenary celebrations,” local resident Peter Gillard recalls.

“I went down for a swim pretty early that day before Balmoral got too crazy.

“It was one of those classic Aussie summer days when you feel lucky to be alive.”

At 7:40 am, the Kawasaki B117 is cruising at 120 knots, tracking east past Taronga Zoo and Bradleys Head, when the unthinkable happened.

PolAir 4, the pride of NSW Police Rescue and in service for just two months, had suffered a catastrophic engine failure, exploding at 1200ft.

“There was a thunderous bang, and the aircraft started to lose control and vibrate very badly,” Chief Pilot Constable Peter Leslie would later say.

Constable Leslie makes a frantic mayday call and heads for Balmoral Oval with fragments of the engine cowling and debris showering local roads, as the crew brace for impact.

Seconds later, the chopper ditches into the water just 50 metres from the shore, before flipping on its side and sinking.

It was very noisy,” one eyewitness told reporters on the scene, “it got so low that people were ducking to get out of the way.

“And then the helicopter came straight over my head and went right between two people who were swimming,” she said.

Constable Leslie and Constable First Class Alan Keane quickly managed to escape the wreckage, but the third crewman was trapped and went down in three metres of water.

As local swimmers and a Navy diving team from HMAS Penguin rushed to help the men, Constable Leslie went underwater in a last-minute effort to save his colleague, Senior Constable Steve Southey.

Constable Southey said: “I remember I took the last breath before it actually tipped upside down. I managed to locate the harness and released that and got another lung full of air, but I realised my foot was stuck inside. As the helicopter was sinking further I was going under, then Pete released my foot.”

“I thought I was going to die; it’s as simple as that.”

All three survived the crash unharmed, with the officers publicly thanking Mosman community members who went to their aid, including an older gentleman who rowed over to the men in a boat.

“Unfortunately, we don’t know your names, but your actions will not be forgotten,” Constable First Class Alan Keane wrote in the Sydney Morning Herald on Jan 20, 1988.

“As you could imagine, the whole event was quite distressing to us. After realising, we had survived the impact we then had to take drastic measures to ensure that we would not drown.

“This letter is the only means by which we can say “thank you”.