UH-1 Hueys of the 1st Air Cavalry Division fill the sky over South Vietnam during Operation Pershing in 1967. Te Vietnam Helicopter Pilots Association estimates that over 4,800 helicopter pilots and crew members were killed in action, out of the more than 100,000 who served. Many veterans returning from the war elected to stay in aviation, and the influx of thousands of highly trained and experienced veteran pilots and maintainers affected the civil industry for decades to come.