Grand Canyon Airlines Flight 6 was a de Havilland Canada DHC-6 Twin Otter that collided with a Bell 206 helicopter call sign Tech 2 over Grand Canyon National Park on June 18 , 1986 . All 25 passengers and crew on board the two aircraft were killed . It remains the deadliest accident involving a helicopter on United States soil , surpassing the crash of Los Angeles Airways Flight 841 in 1968 , which killed 23 people
Los Angeles Airways Flight 841
Los Angeles Airways Flight 841
Grand Canyon Airlines Flight 6