(WBIR - Knoxville) For more than 20 years, Stan Brock has taken to the skies from the Downtown Island Airport in Knoxville in an old Douglas C-47 aircraft.

Brock and other volunteers with the group Remote Area Medical (RAM) have used the plane as a heavy lifter to deliver the gift of healing medicine from above.

"There's no such thing as a routine flight in this aircraft," said Brock. "It gives us the ability to parachute a team of medical workers into some isolated area along with medical supplies."

Brock launched Remote Area Medical in the early 1990s as part of a personal mission to provide free medical services to isolated and rural areas where people are in desperate need of healthcare.

The volunteer group now has several aircraft at its home base in Knoxville. The donated C-47 is the first, the biggest, and the oldest plane in the fleet. It originally served as a wartime workhorse when it was built in 1943.

"It was built in the time when airplanes were really built to last. This was built during World War II. You'll remember 'Rosie the Riveter' and those ladies worked on these planes and made such a huge contribution to the war effort. This is the original cockpit and the same 1,200 horsepower radial engines. You get the same rumble of power when you push the throttles forward on this airplane. It flies as well now as it did back in June 6th, 1944, with the 9th US Air Force."

Brock has a long and interesting history of his own. The philanthropist was one of the famous faces on Mutual of Omaha's Wild Kingdom as a daredevil wildlife expert. He lived in remote regions across the globe, but began his life in England where he experienced the horrors of constant attacks by German bombers as a child. It was during that era he first saw the C-47 hard at work as he witnessed the military build-up to D-Day.

"I was a school boy living in place called Bournemouth on the south coast of England. I remember watching these young American boys not much older than me. They were playing baseball and throwing footballs in the lawns of these places that were resorts during better times before the war. Not even 24 to 48 hours later, all of those boys were going to be climbing into C-47s, climbing into boats, climbing aboard landing craft, and crossing the channel in the greatest invasion the world had ever seen," said Brock.

Brock said he knew there would be an invasion, but did not know if the American forces were there to protect England from a German invasion or if the Allies would be doing the invading. The latter proved true on June 6, 1944.

"When the invasion started, I mean the air was just filled with airplanes. And the channel was filled with hundreds and hundreds of ships," said Brock.

Brock said the C-47 donated to RAM was sent to England prior to D-Day and in all likelihood took part in the invasion. However, there is no way to know exactly what role it played. The C-47 performed a wide variety of tasks during Operation Overlord.

"It could have been towing gliders or dropping 27 paratroopers," said Brock as he walked in the back portion of the RAM C-47 where the original troop seat configuration is still in place. "Each paratrooper would have been sitting here and there was a cable that went along the side. When it was time to jump they would hook on their cables, get up, and go out that door to whatever their destiny was on that terrible night."

Brock tries to veil his emotions, but becomes slightly choked up when he reflects on the young men he saw playing ball prior to D-Day. A large portion of the soldiers likely perished.

"So many of those guys didn't make it. That's what we have to remember today. The reason why we're here and enjoying our freedoms is because of the boys who flew in airplanes like this C-47. We must remember the lives and the sacrifices that were given in order to make our freedom possible," said Brock.

The Allies made it through a murderous German defense and build a lasting legacy of freedom. They did it with help from planes that were built to last and built to make a difference. The C-47 continues to make a difference in the lives of people who need help today.

"This airplane has 71 years of continuous service. Just imagine how many tens of thousands of landings, some of them probably heavy landings, and it is still in tip-top flying condition," said Brock. "But now it's on a totally different mission. It is a museum piece and it is still standing by for that fateful day when we'll see another Katrina or we'll see another earthquake. We can all rush out here, load our supplies, load our doctors, and and fly out to get out there and do the job."

RAM D-Day Service, Saturday, June 7, 2014

You can see the C-47 for yourself on Saturday, June 7, 2014, at 10:00 a.m. at the Knoxville Downtown Island Airport. Remote Area Medical is hosting a D-Day service to honor the service and sacrifice of those who took part in the war effort. The event is free and will feature music and fly-overs.

"It is an absolutely wonderful time with fantastic music," said Brock. "We hope everyone will come out and help us honor those who gave so much for all of us."