Douglas DC-3C accident at LaGuardia Airport, New York, 4 Jan 1971

Accident narrative

On January 4, 1971, at 1832 e.s.t., a Federal Aviation Administration Douglas DC-3C, registration N7, crashed approximately 2,000 feet short of the approach threshold of Runway 4 at LaGuardia Airport, New York. The aircraft was attempting an Instrument Landing System (ILS) approach in instrument meteorological conditions at night. The two pilots, who were the only occupants, received serious injuries, and the aircraft was destroyed.

### The flight

The DC-3 was returning from an administrative flight that had provided transportation for FAA personnel from LaGuardia to Johnstown, Pennsylvania, with an intermediate stop at Pittsburgh. After a delay of just over an hour at Johnstown, the flight departed for LaGuardia.

The pilot-in-command was an experienced pilot of the DC-3. The copilot had approximately 9,160 hours, with 470 hours in the DC-3. Both pilots held Airline Transport Pilot certificates and DC-3 type ratings.

### The sequence of events

Arriving in the New York area, the flight was radar vectored to the ILS final approach to Runway 4 via the Prospect Intersection. The LaGuardia weather observation provided to the pilots reported a 600-foot overcast, 1-1/2 miles visibility in light rain and fog, and surface winds from 060 degrees at 11 knots.

The pilot stated he maintained a relatively high airspeed approaching the Prospect Intersection to prevent delaying traffic behind them. He used one-quarter flaps approaching the intersection and one-half flaps from there on, planning to maintain airspeed until reaching visual conditions. He planned a descent rate of 300 to 500 feet per minute.

The copilot stated that as they broke out of the clouds between 600 and 700 feet, the ILS instrument showed approximately a two-thirds scale "fly right" for the localizer and a one-dot "fly down" indication for the glide slope. He called this to the pilot's attention. The pilot recalled seeing the approach and runway lights at this time, though he noted they looked fuzzy, which he attributed to either glaze ice or fog. He did not turn on the windshield wipers.

At about 400 feet, clear of the clouds in a right turn, the copilot attempted to contact the tower for a landing clearance. Unable to establish communication, he directed his attention into the cockpit to determine the cause of his difficulty. The FAA manual required the pilot not flying to make altitude callouts at 500 feet, 100 feet above minimums, and at minimums. The copilot stated he made no altitude calls after calling the runway in sight because they were "visual."

The pilot considered going around due to the visibility but rejected the idea because he had the runway in sight and was aligned with the centerline. He estimated he divided his attention equally between the windshield and the instruments.

The copilot's next recollection was receiving a landing clearance, looking out to see the lights ahead, and feeling the aircraft was too low. He remembered seeing a telephone pole as he looked up. At an altitude of 53 feet and approximately 2,747 feet short of the threshold, the aircraft struck a street light. It traveled another 700 feet, damaging approach lights and utility poles, before coming to rest inverted against a residence. Ground witnesses reported the aircraft was very low and made a turn back to the left just before the crash.

### What the investigation found

Examination of the wreckage, powerplants, and systems showed no evidence of failure or malfunction prior to impact. The navigational aids were operating within established limits, and the aircraft's altimeters were tested and found capable of normal operation.

The Board noted that a warm front between the Kennedy and LaGuardia airports created strong southwesterly winds aloft and relatively gentle northeasterly surface winds. Winds aloft recorded at Kennedy International Airport showed a 46-knot wind from 224 degrees at 2,000 feet. Other flight crews making the approach reported encountering a tailwind that required high descent rates to stay on the glide slope, with the tailwind effect decreasing at about 400 to 600 feet above the ground.

The Board's analysis indicated the DC-3 passed the outer marker slightly above the minimum altitude. From the outer marker to the crash site, the aircraft averaged a groundspeed of 128 knots and a descent rate of approximately 770 feet per minute. The pilot stated he was not aware of any wind shear.

The Board believes the aircraft broke out of the clouds with a higher-than-normal rate of descent due to the unreported tailwind. The pilot initiated visual corrections—a right turn and an increased descent rate—to return to the ILS centerline and glide slope. As the aircraft descended and the wind shifted to a headwind, the requirement for a high descent rate was reduced. However, because the pilot was not devoting full attention to the flight instruments and was likely distracted by the copilot's communication troubleshooting, he apparently did not notice the change in the glide slope indication. The Board also noted that moisture on the windshield without wipers operating can cause refraction, making outside objects appear lower than they really are.

No evidence of a power application was found. It appears that by the time the pilots realized they needed power, it was too late to apply it before striking the approach lights.

The Board considered whether the corrective lenses required for both pilots played a part in the accident. The captain was wearing his required near-vision glasses, and the copilot was not wearing his, but medical evaluations indicated these conditions would not have compromised distance vision or the ability to read cockpit displays.

### Probable cause

The Board determines that the probable cause of this accident was: "The failure of the pilot to recognize the wind shear condition and compensate for it; the lack of crew coordination in that the copilot did not monitor the approach due to a self-induced communications problem and failed to warn the pilot that the aircraft was too low; and the diversion of the pilot's attention from his primary task of completing the approach and landing. These conditions resulted in a mismanaged ILS and landing approach and the continuation of the descent into ground obstructions."