"There's no greater feeling than when you've actually done some good and saved someone's life," the prince, 30, says in an upcoming documentary.
"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."
Flt. Lt. Wales, as he is known in the RAF, appears in a new series called Helicopter Rescue which starts broadcasting on BBC One Wales on April 8.
It is the second series of the show that was first broadcast in 2012. This year follows the crews at William's base on Anglesey and the RMB Chivenor base in Devon, England.
In one scene, William is the captain as the crew is called to an old slate quarry in Blaenau Ffestiniog, Wales, where a boy has fallen off an old railway bridge onto rocks.
"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," William says.
Other crewmen talk about being "scared at times," while winchman Master Aircrewman Richard Taylor adds, "It's a challenging procedure and inherently dangerous to put a man on a very thin piece of wire, hanging underneath nine tons of helicopter that's susceptible to turbulence and problems itself, and may have to fly away."
SAC Faye Storer, MOD
The Sea Kings are being replaced in the search and rescue service, which will is set to be carried out by a private company headquartered in Texas starting in 2015.
William's current posting in North Wales ends later this year, and he is set to reveal soon whether he will sign up for another stint, move to another part of the military or leave the services to start full-time royal duties, or take a different route outside forces life altogether.