The Duke of Cambridge is to feature in a new series of Helicopter Rescue.
William speaks of his "calling" to save lives as a helicopter pilot in the show, to be screened next month.
The series will also show crew members around William on Anglesey, and at Royal Marines Base Chivenor in Devon.
In an interview for the BBC Wales programme, which features footage of William in action as a search and rescue captain, he says: "There's no greater feeling than when you've actually done some good and saved someone's life.
"I don't think there's any greater calling in life... to be able to see a son or daughter's face when you bring their mother or father back from the edge of death - it's quite powerful."
In one rescue in the four-part series, the Duke captains an aircraft called to save a boy who has fallen off an old railway bridge and on to rocks.
He describes his role once the call comes in: "As captain, you're trying to play out the entire rescue, the transit to the rescue and back again in your mind, and pick up any circumstances or problems you can foresee, and try and fix them on the ground before you get airborne."
The programme will be the first to show extensive footage of the Duke's work as a search and rescue pilot, a BBC spokesman said.
This is the second series of Helicopter Rescue, the first showing on BBC Wales in February 2012 before being transferred to BBC Two.
:: Helicopter Rescue starts on Monday April 8 at 8.30pm on BBC One Wales.