A Royal Australian Navy officer on a training exercise in the UK found himself in the middle of a real-life rescue.

Lieutenant Dan Cochrane is an aviation warfare officer on a three-year exchange with the Royal Navy.

The 33-year-old from Melbourne was taking part in a search and rescue training flight when the helicopter crew picked up a garbled 'Mayday' distress call on their radio.

A kayaker had capsized in the wintry seas off Cornwall in south-west England - luckily just a few miles from where the crew was practising how to rescue people from the water.

"It all happened fairly quickly and smoothly. It was all much quicker than I'd ever expected. I've done extensive search and rescue training, but I've never been in a real incident before. This was a textbook case," Lieutenant Cochrane said.

He was one of two students on the flight and was just about to lower the other trainee on the winch-line to retrieve a dummy when they picked up the distress call.

Lieutenant Cochrane positioned himself in the open doorway at the rear of the large Merlin Mark 2 helicopter and began to look for the kayaker as they circled the search area.

The man, who was correctly equipped with a dry-suit, lifejacket and radio, was soon found clinging to his upturned craft, not far from the rocky cliffs of the Lizard Peninsula.

The crew quickly winched the man into their helicopter and into the care of Lieutenant Cochrane, then flew the 24 kilometres back to their home base at Royal Naval Air Station Culdrose.

"The man was responsive but cold. I checked him for any injuries and asked him all these first-aid questions. He was just very cold and shaking uncontrollably," Lieutenant Cochrane added.

"It made me realise just how well we train and how professionally and slick everything fell into place. Everybody worked together to achieve a successful outcome," he said.

The kayaker was unharmed and handed into the care of naval medics waiting back at the airfield.

Lieutenant Cochrane joined the Royal Australian Navy in 2008 and qualified as an aviation warfare officer and instructor.

Last year, he volunteered for an exchange program with the UK and is currently learning how to operate the Royal Navy's Merlin anti-submarine warfare helicopters.