ASN Aircraft accident McDonnell Douglas DC-9-31 N9345 Duarte, CA

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Last updated: 1 December 2021

Status:	Final
Date:	Sunday 6 June 1971
Time:	18:11
Type:	McDonnell Douglas DC-9-31
Operator:	Hughes Airwest
Registration:	N9345
MSN:	47441/503
First flight:	1969
Total airframe hrs:	5542
Engines:	2 Pratt & Whitney JT8D-7
Crew:	Fatalities: 5 / Occupants: 5
Passengers:	Fatalities: 44 / Occupants: 44
Total:	Fatalities: 49 / Occupants: 49
Collision casualties:	Fatalities: 1
Aircraft damage:	Damaged beyond repair
Location:	7 km (4.4 mls) N of Duarte, CA ( United States of America)
Phase:	En route (ENR)
Nature:	Domestic Scheduled Passenger
Departure airport:	Los Angeles International Airport, CA (LAX/KLAX), United States of America
Destination airport:	Salt Lake City International Airport, UT (SLC/KSLC), United States of America
Flightnumber:	RW706

Narrative:
Hughes Airwest Flight 706, a McDonnell Douglas DC-9-31, and a US Marine Corps McDonnell F-4B Phantom both crashed following a mid-air collision 7 km north of Duarte, California, USA.
All 49 on board the DC-9 and the pilot of the Phantom were killed in the accident.

Flight 706
Hughes Airwest Flight 706 was a regularly scheduled flight from Los Angeles, California, to Seattle, Washington, with intermediate stops at Salt Lake City, Utah, Boise and Lewiston, Idaho, and Pasco and Yakima, Washington.
The flight departed Los Angeles International Airport at 18:02 local time and following radar vectors from Los Angeles Departure Control, contacted the Los Angeles Air Route Traffic Control Center (ARTCC) at 18:06. The flight reported leaving 12,000 feet at 18:09, and the controller advised, "Air West seven zero six red, turn left heading zero four zero until receiving Daggett proceed direct." RW706 acknowledged, "OK. zero four zero direct to Daggett." This was the last recorded transmission from the flight.

Phantom
The U.S. Marine Corps F-4B Phantom, 151458, was part of a two-ship formation that had departed the Marine Corps Air Station (MCAS) El Toro, California on June 4, 1971 on an overnight cross-country return flight to McChord Air Force Base (AFB), Washington. During a refueling stop at Mountain Home AFB, Idaho, on the way back, 151458 was grounded for repairs to have mechanical difficulties checked out. The radar and transponder were inoperative, there as an oxygen system leak and the radar system were degraded. Meanwhile the flight leader continued back to MCAS El Toro.
Maintenance personnel replaced a fuse to fix the radio, but they did not have the personnel to check the transponder. They confirmed the oxygen leak, but could not repair it. No attempt was made to restore the radar to peak performance at that time. The crew of 151458 then flew to Naval Auxiliary Air Station (NAAS) Fallon, Nevada, for further repairs.
The maintenance personnel on duty at NAAS Fallon were unable to provide the appropriate repairs, so it was decided that the Phantom should continue to MCAS El Toro at low altitude.
The flight departed at 17:16, climbed initially to 7500 feet, and then climbed to 15500 feet to clear mountains and some clouds. After crossing the mountains, they descended to 5500 feet and later further down to 1000 feet. Due to deteriorating visibility, they again climbed to 15500 feet northwest of Palmdale.
The Radar Intercept Officer (RIO) was operating the radar in the mapping mode, but, due to the extremely degraded air-to-air detection capability, no airborne targets were seen.

Collision
At 18:11 both crew members of the Phantom jet suddenly noticed the DC-9 on their right hand side. The pilot initiated an evasive roll but a collision could not be avoided.
The Phantom struck the forward fuselage of the DC-9, causing the nose section of the DC-9 the separate from the fuselage.
The F-4 began to tumble violently about the lateral axis and the RIO ejected from the aircraft. He parachuted to the ground without injury.
The DC-9 crashed in a wooded canyon with approximately 60° slopes

Probable Cause:

PROBABLE CAUSE: The failure of both crews to see and avoid each other but it is recognized that they had only marginal capability to detect, assess, and avoid the collision. Other causal factors include a very high closure rate, comingling of IFR and VFR traffic in an area where the limitation of the ATC system precludes effective separation of such traffic, and failure of the crew of BuNo458 to request radar advisory service, particularly considering the fact that they had an inoperable transponder."

Accident investigation:

Investigating agency:	NTSB
Status:	Investigation completed
Duration:	1 year and 3 months
Accident number:	NTSB/AAR-72-26
Download report:	Final report

Classification:

Mid air collision
Loss of control

Follow-up / safety actions

NTSB issued 10 Safety Recommendations

Issued: 21-JUL-1971	To:	A-72-200
INSTALL VIDEO TAPE AT ALL FAA ATC RADAR DISPLAYS, BOTH TERMINAL AND EN-ROUTE FOR USE AS AN INVESTIGATION TOOL. (Closed - Unacceptable Action)
Issued: 21-JUL-1971	To:	A-72-201
INSTALL AN OPEN "AREA" MICROPHONE AT EACH TERMINAL AND CENTER SECTOR POSITION TO RECORD ALL CONVERSATION AT THE CONTROL POSITIONS. (Closed - Unacceptable Action)
Issued: 21-JUL-1971	To:	A-72-202
ESTABLISH CLIMB AND DESCENT CORRIDORS EXTENDING FROM THE TOP OF THE TCA\'S TO THE BASE OF APC, TO REMAIN IN EFFECT UNTIL THE BASE OF APC HAS BEEN LOWERED TO THE TOP OF THE TCA\'S. (Closed - Unacceptable Action)
Issued: 21-JUL-1971	To:	A-72-203
ESTABLISH MORE DEFINITIVE PROCEDURES FOR THE GUIDANCE OF CONTROLLER PERSONNEL IN HANDLING CODE 7700 AIRCRAFT. (Closed - Unacceptable Action)
Issued: 21-JUL-1971	To:	A-72-204
REVIEW RADAR PERFORMANCE MONITORING PROCEDURES TO ASSURE THAT ALL RADAR FACILITIES ARE CAPABLE OF RECEIVING CODE 7700 TRANSPONDER RETURNS. (Closed - Unacceptable Action)
Issued: 15-OCT-1971	To:	A-71-48
REVIEW THE FEASIBILITY OF RESTRICTING ALL TYPES OF LOW LEVEL TRAINING, WHICH REQUIRES AIRSPEEDS IN EXCESS OF THE FAR LIMITATIONS, TO DESIGNATED RESTRICTED AREAS AND LOW-LEVEL NAVIGATION ROUTES. (Closed - Acceptable Action)
Issued: 15-OCT-1971	To:	A-71-49
REPHRASE THE WORDING CONTAINED IN YOUR ALTITUDE/AIRSPEED LIMITATIONS AND DELINEATE EXPLICITLY THOSE INSTANCES WHEREIN AIRSPEEDS IN EXCESS OF 10,000 FEET/250 KIAS LIMITATIONS ARE AUTHORIZED. THE BOARD BELIEVES THAT THE EXCEPTIONS SHOULD BE LIMITED TO THE FOLLOWING: A. CLIMBS AND DESCENTS TO TRAFFIC PATTERNS, AUTHORIZED AND/OR DESIGNATED TRAINING AREAS AND LOW-LEVEL NAVIGATION ROUTES. B. THOSE INSTANCES WHERE SAFETY OF EITHER CREW OR AIRCRAFT REQUIRE OPERATIONS IN EXCESS OF THE LIMITATION. (Closed - Acceptable Action)
Issued: 15-OCT-1971	To:	A-71-50
EXPLORE THE FEASIBILITY OF USING THE AIR INTERCEPT RADAR ON ALL MILITARY AIRCRAFT TO PROVIDE COLLISION AVOIDANCE ASSISTANCE(AS AN ADDITIONAL AID TO THE "SEE AND BE SEEN" CONCEPT, AND SHOULD THIS PROVE FEASIBLE, INSTITUTE AND ESTABLISH PROCEDURES TO USE THE RADAR FOR THIS PURPOSE ON ALL FLIGHTS WHERE ITS USE IS NOT REQUIRED FOR MORE URGENT MILITARY MISSION REQUIREMENTS. (Closed - Acceptable Action)
Issued: 15-OCT-1971	To:	A-71-51
INSTITUTE A PROGRAM TO PROVIDE MORE PUBLICITY TO THE EXISTENCE, FUNCTION, AND USE OF THE FAA RADAR ADVISORY SERVICE IN THOSE INSTANCES WHERE VFR FLIGHT IS REQUIRED THROUGH HIGH-DENSITY TRAFFIC AREAS. CONSIDERATION SHOULD BE GIVEN TO MAKING THE REQUEST FOR SUCH SERVICE A MANDATORY PROCEDURE. (Closed - Acceptable Action)
Issued: 09-NOV-1971	To:	A-71-52
COORDINATE WITH THE DEPARTMENT OF DEFENSE, AND, IN AREAS WHERE A LARGE INTERMIX OF CIVIL AND MILITARY TRAFFIC EXISTS, DEVELOP A PROGRAM TO INSURE THAT APPROPRIATE GRAPHICAL DEPICTIONS OF AIRSPACE UTILIZATION AND TYPICAL FLOW PATTERNS ARE PROMINENTLY DISPLAYED AT ALL AIRPORTS AND OPERATIONAL BASES FOR THE BENEFIT OF ALL AIRSPACE USERS. (Closed - Acceptable Action)

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Photos

accident date: 06-06-1971
type: McDonnell Douglas DC-9-31
registration: N9345

Closing diagram of Airwest DC-9 and F-4 Phantom near Duarte, CA

View from Airwest DC-9 flight deck prior to collision with F-4 Phantom

View from F-4 Phantom flight deck prior to collision with Airwest DC-9

accident date: 06-06-1971
type: McDonnell Douglas DC-9-31
registration: N9345

Map

This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Los Angeles International Airport, CA to Salt Lake City International Airport, UT as the crow flies is 943 km (589 miles).
Accident location: Approximate; accuracy within a few kilometers.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.

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DC-9-30

662 built
6^th loss
6^th fatal accident
5^th worst accident (at the time)
17^th worst accident (currently)

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United States of America

35^th worst accident (at the time)
62^nd worst accident (currently)

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