Boeing 707-331C accident at Jamaica, New York, 12 Dec 1972 (N788TW)

Accident narrative

On December 12, 1972, Trans World Airlines Flight 669, a Boeing 707-331C cargo aircraft (N788TW), crashed during an instrument landing system (ILS) approach to John F. Kennedy International Airport in Jamaica, New York. At 2256 eastern standard time, the aircraft struck a wooden pier supporting approach lights just short of the runway threshold. The three flight crewmembers, the only people aboard, escaped without injury, but the aircraft was destroyed.

**The flight** Flight 669 was a scheduled cargo trip from Friendship International Airport in Baltimore, Maryland, departing at 2225. The crew consisted of Captain John J. Clancy, who had 19,938 total flight hours with 8,400 in the Boeing 707; First Officer Robert W. Jones, who had 4,717 total hours with 2,971 in the 707; and Second Officer Fred P. McIntyre.

A 2251 weather observation at JFK reported an indefinite 200-foot ceiling, obscured sky, half-mile visibility in light drizzle and fog, and a variable runway visual range of 4,500 to more than 6,000 feet. The captain decided to make a Category II ILS approach to Runway 4R using the autopilot, approach coupler, and autothrust systems. This approach authorized a descent to a Decision Height (DH) of 162 feet.

**The approach** During the descent, the autopilot was used. As the aircraft intercepted the localizer and glide slope, the landing gear was lowered and flaps were extended. The captain manually advanced the thrust levers slightly, commenting that he was uncomfortable with the low approach airspeed. At the outer marker, the aircraft crossed at the published altitude of 946 feet, and the first officer reported no instrument warning flags.

As the aircraft descended, the captain called out "500 feet" and the first officer called "speed 130, sink 600." The radio altimeter emitted a two-second warning tone indicating 500 feet absolute altitude. Shortly after, the first officer saw the glow of approach lights through the clouds.

At 2254, 13.2 seconds after the altimeter tone, the cockpit voice recorder captured a distinct click, and the engine noise level decreased. Over the next 20 seconds, the first officer called the approach lights in view, and the captain noted they were 100 feet above DH.

The first officer then warned that the aircraft was low. Less than a second later, the DH alerting tone sounded. The first officer called "Runway lights" and then "Runway in sight." Engine noises increased briefly, but 3.3 seconds later, the copilot called out, "You're too low, man! too low! too low." Engine noises decreased again, and the crash occurred one second later.

The captain later stated he had seen the centerline of the approach lights and believed the aircraft was in position for a normal landing when it struck the pier. The first officer recalled hearing what he thought was the autopilot disconnecting. He stated the aircraft appeared to be on a normal approach path until he noticed a rapid increase in the descent rate and saw a "flattening of the scene" as they descended rapidly toward the red approach lights, prompting his warning.

The captain applied thrust and rotated the aircraft, but it struck the wooden pier and momentarily became airborne again. It touched down on the runway and began to skid to the right. The aircraft left the runway, skidded 800 feet across sandy ground, and pivoted 180 degrees. It came to rest 500 feet from the runway edge. All four engines and the main landing gear separated during the deceleration. There was no fire.

**What the investigation found** The Board examined the weather and noted a 42-knot tailwind component at 1,500 feet that lessened to light winds at 500 feet. The Board determined these conditions were within the capabilities of the aircraft and the autopilot functions. Post-accident checks found the localizer and glide slope facilities were operating within certification standards.

Flightpath data revealed that the aircraft's apparent rate of descent increased to 1,140 feet per minute shortly after the first officer saw the glow of the approach lights, the click was recorded, and engine noise decreased. The Board concluded that the autopilot, and thus the glide slope function, was disconnected before the aircraft reached decision height.

The Board further concluded that after the autopilot was disconnected, the crew did not make additional reference to the electronic glide slope displays to assess their descent path. The captain did not realize the flightpath trajectory had changed, and the copilot did not recognize the change until he saw the scene flatten, leaving too little time to recover. The Board noted that if the autopilot had not been disengaged until the minimum authorized altitude, or if the nonflying crewmembers had continued to monitor the flight instruments, the aircraft would have reached the runway safely.

**Probable cause** The National Transportation Safety Board determined that "the probable cause of this accident was that the captain did not maintain a safe descent path by visual external reference during an instrument landing system approach."