Decades after she thought her son died during the Fall of Saigon in 1975, a woman and a Newton, Massachusetts, man reunited. April 30 marks 50 years since the Fall of Saigon, a day for many Vietnamese Americans to honor lives lost and reflect on those forever changed by the Vietnam War, including David Nguyen, who reunited with his birth mother 40 years after she thought he died during Operation Babylift.Tragedy struck the first plane out of Saigon, killing 138 people, mostly children, in a crash. Nguyen's birth mother thought he was among them. "My birth mother heard the story, and she was just like, 'Oh my God, I think my child, my son was on that plane.' And so for 40 years until the day I showed up in 2015, she thought she had killed her only child," Nguyen said.In 1975, Nguyen was in the care of an American-run orphanage. His single mother, a double-operative in the military, had no choice but to place him in what she thought was temporary care. "She happened to get really sick, and the doctors were saying, 'Oh, bring him over here. The Americans will take care of him while you recover.' So it's almost like they thought it was some sort of day care," Nguyen said. As the fall of Saigon became imminent, President Gerald Ford's administration made the controversial decision to launch the mass evacuation of orphaned children out of the city in early April 1975. Nguyen's birth mother assumed he was on that doomed first flight. "As a parent myself now, I can't even imagine holding that inside of you for 40 years and not telling anybody that you had a child," Nguyen said.Meanwhile, half a world away in Newton, Chuck and Pat Redmon heard the same news and worried the little boy they were in the process of adopting had been in the plane crash. They felt relieved when they found out he would be on the next flight. That little boy became David Redmon when he arrived in the United States and grew up the youngest of four children, living what many would consider an "all-American" life. "I played a lot of sports and had friends and everything," Nguyen said. However, a piece of his identity and culture was always missing. As a young adult, he legally changed his last name back to Nguyen and began searching for his birth mother. "My adoptive mother was always very curious. I mean, both of them were always very curious to know more about the story and know more about Babylift," Nguyen said.He started his search with childhood pictures from the orphanage and a document referred to as a Statement of Relinquishment. A private investigator and a viral post on social media led to Nguyen reuniting with his birth mother in 2015 -- 40 years after she thought he died in Operation Babylift. "So, I land, she's there, and we just embraced for a long time," Nguyen said. "It was like I didn't have that much time to really process it. And so it was like, I hugged her. We held on for a pretty long time, and then I just found myself, we were holding hands."Despite the language barrier, Nguyen said he could feel the love and understood the sacrifice she made in a time of war. "Now that I've reconnected with her, I can feel her sense of loss, and it's a major sense of loss for her, having lost a child and holding it in all these years and everything," he said.Since reconnecting with both his birth mother and his cultural identity, Nguyen has decided to write a memoir about his adoption story and Operation Babylift.