Allegheny Airlines Flight 485

Investigators from the National Transportation Safety Board analysed the cockpit voice recorder (CVR) and flight data recorder (FDR) for information as to the cause of the accident, and found it was likely Captain Eastridge made several decisions during the course of the flight which indicated the time of the journey was important to him.[8] Prior to take-off from Washington D.C., Eastridge requested an amended flight plan from the Allegheny Airlines flight dispatcher. He asked the dispatcher to remove the planned refuelling at Groton from the flight itinerary, and asked ground crews at Washington D.C. to add more fuel to the aircraft. Investigators found this decision was likely made in case poor weather at the airport forced him to abandon a landing attempt and proceed directly to New Haven.[8]

When the flight departed from the gate, air traffic control (ATC) gave the aircraft permission to taxi to Runway 15. The flight crew then contacted ATC to request the use of Runway 3, which they were closer to. The NTSB report noted, "Time would have been saved if Runway 3 could have been utilized as it is closer to the company gate and more nearly aligned with the routing to be flown after take-off." ATC approved this runway change, and cleared the aircraft for take-off.[8]

Shortly after take-off, the flight crew received clearance from ATC to initiate a 360 degree turn. Eastwood decided to cancel his instrument flight rules (IFR) flight plan, and elected to fly using visual flight rules (VFR).[8] The NTSB report noted, "The captain obviously was aware that if he proceeded VFR via the most direct course time could have been saved. Evidence indicates that this was his plan."[8]

The NTSB noted that the "Eastridge carried out the first portion of the flight exactly as planned."[8] Therefore, upon reaching Groton, where the weather was poor, Eastridge elected not to divert to an alternate airport or proceed direct to New Haven, but circle overhead until conditions improved.[8] About 30 minutes after they began circling above the airport one third of the fuel available for holding had been consumed, and Eastridge approached the airport to attempt a landing. "Thinking ahead," the NTSB noted, "about fuel requirements and down-line scheduled operations, the captain attempted to get his airplane onto the ground."[9] But, because of the poor visibility, Eastridge decided that, to see the runway before landing, he would have to descend to 200 feet (61 m) within 1 mile (1.6 km) of the runway, far below the minimum descent altitude of 510 feet (160 m). The NTSB report stated, "He decided to descend to about 200 feet, calculating that sufficient visibility would be available to permit a safe landing. Although such a procedure was not authorized, the captain believed that he could conduct the approach safely."[9]

The NTSB determined the accident was survivable,[10] and the bodies of 15 of the 27 dead passengers were located near the rear service door, which could be manually opened by passengers. The door lock was found in the closed position. Medical examination was undertaken on 26 of the 27, and all had died from chemical asphyxiation or burns. The stewardess had also obtained fractures to the ribs, left clavicle and her third thoracic vertebrae.[11] The accident report stated many of the passengers may have tried to leave the aircraft, but were overcome in doing so.[12]

Several witnesses stated that, when they first arrived at the accident site, they heard voices of people inside the aircraft and that several violent explosions occurred shortly after impact. The female surviving passenger also recalled seeing seven or eight persons up and moving about the cabin and hearing the sound of a male voice calling, "Try to get to the back."

— National Transportation Safety Board, Accident report, 1972[12]

In their analysis of the accident, the NTSB stated that, "with the exception of the captain, who sustained fatal injuries on impact, everyone aboard this flight could have survived if rapid egress from the fire area had been possible or if flame propagation had been retarded."[13] They found that, because of the position of the bodies of the passengers, an unsuccessful attempt had been made to open the rear service door. The instructions, printed on the inside of the door, would have been difficult to read in the smoke.[13]

Investigators concluded the evacuation could have been more successful had another steward been aboard the aircraft. Although two cabin crew are legally required aboard a Convair CV-580, an exemption had been granted to Allegheny Airlines and several other carriers, permitting them to fly with one cabin crew. The Board stated they believed "the possibility for a greater number of survivors would have existed had a second cabin attendant been aboard this flight."[13]