Pan Am Flight 799

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Pan Am Flight 799
Boeing 707-321C, Pan Am JP6922271.jpg

An identical Boeing 707-321C from Pan Am
Accident summary
Accident type Coming off the runway due to non-activated buoyancy aids
place Elmendorf Air Force Base , Alaska , United StatesUnited StatesUnited States 
date December 26, 1968
Fatalities 3
Survivors 0
Aircraft
Aircraft type United StatesUnited States Boeing 707-321C
operator United StatesUnited States Pan American World Airways
Mark United StatesUnited States N799PA
Surname Clipper Racer
Departure airport Los Angeles International Airport , California , United StatesUnited StatesUnited States 
1. Stopover Ted Stevens Anchorage International Airport , Alaska , United StatesUnited StatesUnited States 
2. Stopover Tokyo , JapanJapanJapan 
3. Stopover Da Nang Air Base , South Vietnam
Vietnam SudSouth Vietnam 
Destination airport Cam Ranh Airport , South Vietnam
Vietnam SudSouth Vietnam 
Passengers 0
crew 3
Lists of aviation accidents

Pan-Am flight 799 (flight number: PA799 , radio call sign: CLIPPER 799 ) was a Pan American World Airways charter cargo flight on December 26, 1968, on which the Boeing 707-321C N799PA crashed while taking off from Elmendorf Air Force Base . All three occupants of the machine were killed in the accident.

plane

In the crashed plane, it was a Boeing 707-321C, which in 1964 in the work of Boeing on the Boeing Field in the State of Washington US than the 397. Boeing 707 off the production line with the serial number 18824 was finally assembled. The first flight of the machine took place on December 17, 1964, on December 31, 1964 it was delivered to Pan Am, where it went into service with the aircraft registration N799PA . The machine was given the name Clipper Racer . The four-engine long-range narrow-body aircraft was equipped with four turbofan engines of the type Pratt & Whitney Jt3d-3B equipped.

crew

There was a three-person crew on board the machine, consisting of a flight captain, a first officer and a flight engineer. The flight captain was the 47-year-old Arthur Moen, who had completed a total of 15,207 hours of pilot time including 3,969 hours in the cockpit of the Boeing 707 and had been flying for Pan Am since 1949. First officer was 38-year-old Johannes D. Markestein, who had 9,813 hours of flight experience, 2,813 hours of which he had completed in the cockpit of the Boeing 707. He had been with the airline since 1957. The flight engineer was the 31-year-old James R. Skellenger, who had 3,032 hours of flight experience, including 138 hours in the Boeing 707. The three crew members had not previously flown together in this configuration, although the master and first officer had previously flown together twice From Anchorage.

Flight plan

The flight PA799 was an intercontinental charter cargo flight during the Vietnam War taking place at the time . The numbers of the aircraft registration number of the aircraft used were used as the flight number. The machine carried cargo and mail from Los Angeles to Cam Ranh Bay. For the flight to Cam Ranh Bay, stopovers for refueling in Anchorage and Tokyo were planned. In South Vietnam , the Đà Nẵng Air Base should also be served. During the stopover in Anchorage, a new crew was due to board.

Flight history

The take-off from Los Angeles International Airport went according to plan and there were initially no special incidents on the flight. The plane was then diverted to Elmendorf Air Force Base via Alaska , as Anchorage Airport was closed due to the difficult weather conditions. After landing, the crew found that the thrust reverser of engine no. 4 (far right) was out of order.

the accident

When the weather conditions in Anchorage improved and the crew received clearance to fly to the airport, the plane was two hours late. The engines were started at 5:55 a.m. local time, and at 6:02 a.m. the crew received clearance to taxi for the runway. The pilots received clearance to take off from runway 05. However, they asked to be able to take off from runway 23, as it was longer. Captain Moen had retracted the buoyancy aids to protect them from icing. While the pilots worked through the checklist for takeoff, they were offered a follow-me car that would guide them to the runway. After the machine had reached the runway thanks to the follow-me car, two United States Air Force machines took off in front of it.

The take-off run began at 6:15 a.m. At this time, First Officer Markestein was in control of the machine. Immediately after the machine took off, the stall warning system was activated . The machine then rolled to the right with the wing touching the ground. Just 59.2 seconds after take-off, the machine fell to the ground just beyond the runway end of runway 23 at Elmendorf Air Force Base, exploded and went up in flames, killing all three crew members.

Accident investigation

The National Transportation Safety Board (NTSB) investigated the accident. The direct cause of the accident was found to be the execution of a take-off without activated buoyancy aids . The NTSB found that the deployment of the buoyancy aids was only listed on the checklists for taxiing to the runway, not on the checklists for take-off. It turned out that the captain had initially deployed the buoyancy aids, but then brought them in again in accordance with Pan Am's operating regulations to protect them from icing. As the buoyancy aids were not listed on the checklists for take-off, the pilots were no longer reminded to deploy them. During take-off, the warning system, which was supposed to warn the crew before the take-off was carried out with an incorrect take-off configuration, also failed. This came about because Pan Am had not implemented Boeing's service instruction 2384 of January 31, 1967, which stated that the trigger point of the warning system should be reduced from 42 to 25 degrees of thrust lever position in order to ensure that the system also operates under wintry conditions Conditions works fine. This was because cold air creates more lift and therefore winter takeoffs require less thrust. Pan Am stated without giving any reason that Boeing's service instructions were not applicable to Pan Am's machines.

consequences

After the accident, the NTSB recommended that Boeing's maintenance instruction 2384 should be made mandatory by the Federal Aviation Administration . A corresponding airworthiness directive was published on May 28, 1969. It was also recommended to modify checklists in such a way that critical work steps are listed again on the start checklists. The latter recommendation was only inadequately implemented in US civil aviation, so that on August 16, 1987 on Northwest Airlines Flight 255 another similar accident occurred to a McDonnell Douglas DC-9-82 (MD-82) 155 people were killed and in which inadequate checklists played a role again.

swell

Coordinates: 61 ° 16 ′ 0 ″  N , 149 ° 50 ′ 0 ″  W.