Hughes Airwest Flight 706

Hughes Airwest Flight 706 was a regularly scheduled flight operated by American domestic airline Hughes Airwest from Los Angeles, California, to Seattle, Washington, with several intermediate stops. On Sunday, June 6, 1971, the McDonnell Douglas DC-9 serving as Flight 706 departed Los Angeles just after 6 p.m. en route to Seattle as a McDonnell Douglas F-4 Phantom II of the United States Marine Corps was approaching Marine Corps Air Station El Toro near Irvine at the end of a flight from Naval Air Station Fallon in Nevada. The two aircraft collided in midair over the San Gabriel Mountains near Duarte, killing all 49 aboard the DC-9 and the F-4 pilot; the F-4 radar intercept officer ejected and survived.

The crash of Flight 706 prompted the United States Armed Forces to agree to reduce the number of military aircraft operating under visual flight rules in civilian air corridors and to require military aircraft to contact civilian air traffic controllers.

Flight histories

Flight 706 was a scheduled passenger flight from Los Angeles International Airport, California, to Seattle–Tacoma International Airport, Washington. The McDonnell Douglas DC-9-31 aircraft had accumulated more than 5,500 airframe hours since entering service in 1969. It was operating under the livery and name of Air West; the airline had been recently purchased by Howard Hughes and rebranded Hughes Airwest. The aircraft was piloted by Captain Theodore Nicolay, age 50, who had logged about 15,500 hours of total flying time, with more than 2,500 hours in DC-9s. His co-pilot was First Officer Price Bruner, age 49, who had over 17,100 total hours' flying time and almost 300 hours in DC-9s.

Flight 706 departed from Los Angeles at 6:02 pm PDT, bound for Salt Lake City, Utah, the first of the five intermediate stopovers, followed by Boise and Lewiston in Idaho, and Pasco and Yakima in Washington before ending at Seattle. Control of the flight was transferred to Los Angeles Air Route Traffic Control Center at 6:06 pm, four minutes after takeoff, and passed through 12000 ft at 6:09 pm and instructed to head 040 (magnetic) until receiving the Daggett VOR, then direct. Flight 706's acknowledgement of this instruction was the last radio transmission received from the aircraft.

The U.S. Marine Corps McDonnell F-4B-18-MC Phantom II, Bureau Number (BuNo) 151458, coded '458', had been in operation since April 15, 1964. At the time of the accident, it was assigned to Marine Fighter Attack Squadron 323, Marine Aircraft Group 11, 3rd Marine Air Wing, though it had been operated by various squadrons prior to that. The fighter plane was piloted by First Lieutenant James R. Phillips, age 27. The radar intercept officer was 1st Lt. Christopher E. Schiess, age 24. Between them, the crew had more than 1,000 total flight hours. The jet and its crew were based at MCAS El Toro in Orange County, near Irvine.

'458' was part of a cross-country flight of two aircraft when its radio failed while landing at Mountain Home Air Force Base in southwest Idaho. According to routine orders, the aircraft was to effect repairs at Mountain Home AFB and then return to MCAS El Toro. Diagnostic tests at Mountain Home revealed the aircraft had an inoperative radio, an inoperative transponder, oxygen system leak, and a degraded radar system. Maintenance personnel were able to fix the radio and confirm the oxygen leak, but the base did not have the necessary personnel to repair either the transponder or the radar.

Despite the inoperative transponder, Phillips received permission from his superiors to fly the F-4B anyway. As the fighter proceeded to NAS Fallon in Nevada, the oxygen leak deteriorated until the system was disabled completely, and the pilot was instructed to fly at low altitude. The Phantom II departed NAS Fallon at 5:16 pm following a flight plan routing across the Fresno, Bakersfield, and Los Angeles air corridors.

Flight 706 was operating under instrument flight rules (IFR). Under IFR procedures, the pilot guides the aircraft using the cockpit's instrument panel for navigation, in addition to radioed guidance from air traffic controllers and ground radar. BuNo 151458 was operating under visual flight rules (VFR). At the time of the accident, VFR required pilots to "see and avoid" other aircraft, a doctrine that dates back to early aviation. The "see and avoid" rule requires pilots of all aircraft flying in VMC to maintain vigilance for other aircraft flying in their vicinity, in addition to traffic advisories from ATC.

Collision

Near the Bakersfield Flight Service Station, the crew of '458' decided to deviate east from their flight plan to avoid heavy air traffic in the Los Angeles area. Phillips was forced to climb to 15500 ft from 1000 ft because of deteriorating weather conditions. Meanwhile, shortly after takeoff, Flight 706 received two radar traffic advisories, neither of which indicated the presence of '458'.

Soon after reaching 15500 ft, the fighter's DME (radio) showed MCAS El Toro was 50 nmi away. The pilot of '458' then performed an aileron roll, a flight maneuver that rolled the aircraft 360° to allow the pilot to observe any air traffic above or below the aircraft. Schiess, the radar intercept officer, was operating the fighter's radar, which was unable to detect any aircraft due to its deteriorated condition. Because of the stowed position of the scope, he had been leaning forward and looking downward at the instrument. Between three and ten seconds prior to the collision, he glanced up, suddenly observed the DC-9 in his peripheral vision and shouted a warning to the pilot. The pilot attempted an evasive roll, but was unable to clear the oncoming airliner.

Around 6:11 pm, Flight 706 and '458' collided at about 15150 ft altitude, over the San Gabriel Mountains in the vicinity of Duarte. The collision tore the F-4's tail off, and the DC-9's cockpit was similarly ripped off as a result. The stricken airliner "cartwheeled" through the air and plunged downwards. Witnesses in nearby Duarte described hearing a loud noise and seeing two flaming objects falling from the sky. A second explosion shook the area as the DC-9 struck the mountain. Schiess ejected from the F-4B and parachuted to safety; Phillips, the pilot, could not eject and was killed in the crash. The F-4B crashed on Mount Bliss, about 1 mi from the airliner wreckage. Burning debris from the collision and subsequent crashes set off numerous small brush fires in the area. Wreckage was scattered across a mile of nearly inaccessible terrain in the Angeles National Forest.