Douglas DC-8-63F accident at US, 27 Jul 1970

Accident narrative

On July 27, 1970, Flying Tiger Line Flight 45, a Douglas DC-8-63F cargo aircraft, crashed into the water approximately 2,200 feet short of Runway 18 at Naha Air Base in Okinawa, Ryukyu Islands. The four crewmembers, who were the only occupants on board, died as a result of the accident. The aircraft was destroyed.

**The flight** Flight 45 was a regularly scheduled international cargo flight from Los Angeles, California, to Da Nang, Republic of Viet Nam. The crew took over the flight in Tokyo, Japan, departing for Naha at 0929 local time.

The flight proceeded without reported difficulty and was cleared for an en route descent to 1,000 feet mean sea level to make a precision radar approach to Runway 18 at Naha. The final approach controller established radar contact 18 miles northwest of the airport. The weather was generally good with bright areas of noonday sunlight, but a heavy, localized rain shower sat directly on the final approach path just north of the runway.

**The approach** The controller advised the crew of construction equipment near the runway and that there was reduced visibility on final, noting that the approach and strobe lights were on. The cockpit voice recorder captured the crew completing the landing checklist, including flaps, radio altimeters, gear down, and spoilers armed.

At slightly less than 5 miles from touchdown, the flight was instructed to begin its descent onto the glidepath and was cleared to land. At 1135:07, a sound similar to the blowing of the pneumatic rain removal system began and continued steadily to the end of the recording.

The controller provided heading changes and glidepath updates, advising at 1135:14 that they were dropping slightly below the glidepath with a 10-knot tailwind. At 1135:34, the controller advised the crew that they were on the glidepath.

Flight data recorder correlation showed the aircraft leveled off at about 325 feet for seven seconds, during which engine power was reduced. Following this brief level flight, the aircraft began an uninterrupted descent averaging 1,150 feet per minute.

At 1135:42, an unidentified person in the cockpit called out, "Hundred feet." One second later, the controller transmitted, "At minimum altitude, going well below glidepath, too low..." While the controller was transmitting, the unidentified cockpit voice called, "Seventy feet," and then, "It's fifty feet."

The aircraft struck the water at 1135:45.5. Ground witnesses reported seeing the aircraft emerge from the heavy rain and low clouds at an estimated altitude of 75 to 100 feet before it crashed.

**What the investigation found** The main wreckage was located in water varying from 6 to 70 feet deep. The Board noted the accident was survivable; the cockpit section came to rest inverted and partially submerged. Two crewmembers survived the impact and spoke to rescuers, with the first officer stating, "Everything was okay until we hit." Both subsequently drowned before they could be extracted, as rescuers were unable to cut through the fuselage due to fears of igniting aviation fuel on the water. The captain died from head injuries and the navigator from asphyxiation.

The Board found no evidence of engine, system, or structural failure. The first officer was flying the approach while the captain handled communications. Company procedures required the pilot not flying to call out 500 feet and 100 feet above minimums, but neither call was made. The investigation noted a lack of clear understanding between the pilots regarding the decision height: the first officer's radio altimeter bug was set to 300 feet, while the captain's was set to 200 feet.

Simulator tests indicated that the high rate of descent was likely caused by a combination of a sudden decay of the 10- to 15-knot tailwind, the application of minimal control forces, and the reduction in engine power.

The Board analyzed the visual conditions as the aircraft passed through the rain shower. Bright sunlight illuminating the rain from behind would have created a "veiling glare" or "Ganzfeld" phenomenon—a homogeneous visual field that obscures contrasting objects and causes severe visual disorientation. This glare would have made it extremely difficult for the pilots to see the runway or their instruments. Furthermore, the pneumatic rain removal system's efficiency was reduced because of the low engine power setting during the final descent.

The investigation also found that the final approach controller transmitted the minimum altitude warning one second after the "hundred feet" call in the cockpit. The aircraft was actually at about 85 feet when the controller called the 214-foot minimum altitude. The Board noted that the controller's continuing attention to azimuth displays might have limited his observation of the elevation display, and the delayed warning negated its alerting effect.

**Probable cause** The National Transportation Safety Board determined that the probable cause of this accident was "an unarrested rate of descent due to inattention of the crew to instrument altitude references while the pilot was attempting to establish outside visual contact in meteorological conditions which precluded such contact during that segment of a precision radar approach inbound from the Decision Height."