Convair 240 accident at Portland, Maine, 29 Mar 1956

Accident narrative

On March 29, 1956, at 2204, Northeast Airlines Flight 124 landed in deep snow to the left of runway 20 at the Portland, Maine, Municipal Airport. The Convair 240’s nose gear folded back, resulting in major damage to the aircraft. Five of the 32 passengers sustained minor injuries; the crew of three was uninjured.

**The flight**

Flight 124 was a scheduled service from La Guardia Field, New York, to Bangor, Maine, with intermediate stops including Boston and Portland. The crew consisted of Captain Ayres R. Chaves, who had 5,568 flying hours in the Convair 240; Captain Robert A. Lebewohl, acting as first officer, with 2,437 hours in the aircraft; and Stewardess Jean L. Anderson. The aircraft’s takeoff weight was below the maximum allowable.

After an uneventful first segment, the flight departed Boston at 2120 on an Instrument Flight Rules (IFR) flight plan. At 2147, Air Route Traffic Control cleared the flight to descend from 3,000 to 2,000 feet and make an instrument approach to Portland. Weather at the airport was reported as a 900-foot precipitation ceiling, sky obscured, and visibility of 1-1/2 miles in light snow.

The pilots stated they briefly saw the airport from 2,000 feet over the low frequency range station and executed an instrument approach to runway 15. Upon establishing visual reference at approximately 1,000 feet above the ground, the flight was cleared for a circling approach to runway 20, which Captain Chaves selected for its length, grade, and the existing winds.

Captain Chaves stated that while turning onto the final approach, he picked out the runway lights and instructed the first officer to complete the landing checklist. Landing flaps were extended and landing lights turned on. The captain recalled that the area he assumed to be the runway was white and without wheel tracks, which seemed normal due to the falling snow. Approach speed, altitude, and alignment appeared good.

Upon touchdown, the pilots said the aircraft decelerated very rapidly, nosed down as the nose gear collapsed, and stopped abruptly after a short slide. Evacuation through the front door was orderly but slow, as several passengers insisted on retrieving personal belongings despite the captain's objections.

**What the investigation found**

Investigators found that the aircraft had landed parallel to and left of runway 20 in 18 to 24 inches of packed snow. The touchdown point was approximately midway between the left row of white runway lights and a parallel row of white boundary lights. The lateral distance between these two rows of lights was about 168 feet, closely matching the 160-foot distance between the actual left and right rows of runway lights.

The sliding action caused extensive damage to the lower nose section. Both engines remained in place, but the nose section of each engine and its respective propeller were torn off as the aircraft slid forward. Examination of the aircraft and its systems revealed no malfunction or failure prior to impact.

An examination of the airport lighting revealed that ten lights along the right edge of runway 20 were inoperative, broken, or covered by snow. Eight of these were consecutive, beginning at the approach end. The broken lights had been struck by snowplows during previous snow-removal operations and appeared to have been broken for a considerable period. The affected lights covered about half of the runway's 4,260-foot length.

At the time, the City of Portland's policy during the snow season was to defer replacing broken lights until spring unless pilot complaints indicated too many were broken. Tower personnel stated they were unaware of the broken lights because snowbanks obscured the area from their view. Furthermore, Northeast Airlines ground personnel at Portland had sent two field condition reports to the Boston operations office on the day of the accident stating "Lites Normal." The station manager indicated this report was based on the city's snow season policy rather than the actual condition of the lights.

The Board noted that as the pilots made their final approach, they saw the row of field boundary lights and the left row of runway lights. Because these rows were of the same color and comparable spacing, the Board concluded they undoubtedly appeared to the pilots as the left and right rows of runway lights, creating an illusory runway to the left of runway 20. The Board noted that with moderate falling snow restricting visibility and the normal tendency to concentrate on the first third of the landing area, it was understandable why the pilots did not see the operating lights on the far half of the right side.

The Board believed that the airline's field condition reporting procedure was inadequately complied with, and that the City of Portland's policy for maintaining airport lighting was inadequate. The Board believed sufficient inspections should be made to ensure accurate knowledge of lighting conditions so that users are placed on notice.

**Probable cause**

The Board determined that the probable cause of this accident was "inadequate maintenance of runway lights and incorrect reporting of their condition resulting in an illusionary position of the runway under conditions of low visibility."