 On 6 June 1971 , Hughes Airwest Flight 706 , a McDonnell Douglas DC @-@ 9 @-@ 31 collided in mid @-@ air with a United States Marine Corps F @-@ 4B Phantom above the San Gabriel Mountains , while en route from Los Angeles International Airport to Salt Lake City . All 49 on board the DC @-@ 9 and one of the crew on the F @-@ 4 were killed . 
