Convair 240 accident at Columbus, Ohio, 27 Jun 1954

Accident narrative

On June 27, 1954, at 2015, American Airlines Flight 572 and a United States Navy SNB collided in mid-air 0.6 mile east of Port Columbus Airport in Columbus, Ohio. Both aircraft were on final approach to runway 27. The Navy SNB caught fire at impact, crashed, and burned, fatally injuring its two occupants and destroying the aircraft. The American Airlines Convair 240 continued its approach and landed. During the landing roll, its damaged nose gear collapsed, and the aircraft slid 4,200 feet along the runway. None of the 32 passengers, including one infant, or the three crew members aboard the Convair were seriously injured.

### The flights

American Airlines Flight 572 was a scheduled visual flight rules (VFR) operation from Memphis, Tennessee, to Cleveland, Ohio. The crew consisted of Captain J. C. Pollard, First Officer J. S. Myrick, and Stewardess M. J. Gunn. The aircraft departed an intermediate stop at Dayton, Ohio, at 1952, with the first officer flying from the right seat.

The Navy aircraft, a twin-engine Beechcraft SNB, was on the return leg of a training flight from West Lafayette, Indiana, to the Port Columbus Naval Air Station. It was piloted by Lieutenant Commander J. R. Hoerath, with Lieutenant Commander D. Edgar acting as observer.

### The sequence of events

At approximately 2007, the American flight contacted the Columbus tower. The tower gave landing information and approved a requested right traffic pattern to runway 27. The Convair began a shallow descent and established a downwind leg northwest of the airport. The tower advised the flight it was number two to land, following a TWA Martin making a straight-in approach to runway 27.

Around 2009, the Navy SNB called the tower for landing information. The tower initially advised the flight to use runway 27, but the SNB requested and was granted permission to use runway 30, subject to traffic. The SNB entered a left downwind leg for runway 30.

The local controller had assumed his position about five minutes before the accident. The tower facility was considered marginally adequate; originally built for weather observation, it featured 140 small glass panes, eight concrete support columns, and a canvas-covered radar installation that required the controller to stand and move continuously to observe traffic. The controller was busy, making 28 transmissions and receiving 43 replies in the eight minutes before the collision.

The controller transmitted simultaneously on the VHF frequencies used by the two aircraft and the UHF frequency used by taxiing military traffic. This allowed both crews to hear all tower transmissions, but because they transmitted to the tower on different frequencies, they could not hear each other.

Realizing that runways 27 and 30 intersected and that spacing was insufficient for the SNB to land on 30 before the Convair landed on 27, the controller instructed the SNB to follow the TWA Martin on runway 27 or circle the field. The SNB acknowledged and reported it was on downwind for runway 27. The controller did not advise the American flight of these instructions, leaving both aircraft sequenced to follow the same TWA flight.

When the SNB reported on base leg for runway 27, the controller could not see it. He advised the SNB to continue its approach but did not ask for its position or inform the Convair, which was seen turning onto its own base leg shortly after. The controller stated he did not issue advisories because the SNB was not in sight and he felt altering either aircraft's position might create a hazard.

The controller next observed both aircraft on final approach about two miles east of the runway. The SNB appeared to him to be below, to the right, and behind the Convair. The controller transmitted: "Navy seven seven three, I have two aircraft on the final approach, one is American Convair high and you appear to be slightly behind and to the right, is that correct?" The Navy crew replied in the affirmative, stated they had the aircraft in sight, and asked if they should go around. The controller instructed the SNB to make a three sixty or circle the field and follow the Convair. The SNB's landing gear was seen to retract, and it began a shallow left turn just before the collision.

Aboard the Convair, about 300 feet above the ground, the crew felt a violent jar and a simultaneous yaw to the left. Captain Pollard took control, noted the left engine had stopped, and landed the aircraft.

Following the gear collapse and slide, Stewardess Gunn opened three right-side window exits and the rear service door. Captain Pollard released the forward passenger door, but because the nose rested on the runway, it could not be used until First Officer Myrick evacuated through the right cockpit window and pulled the stairway ramp outward. Sixteen passengers evacuated using an emergency rope at the rear door, 13 used the forward door, and two used the window exits. The infant was dropped through the rear door to a passenger on the ground. Ten passengers and the stewardess received minor rope burns. Two small friction fires in the Convair were quickly extinguished by ground crews.

### What the investigation found

The accident occurred ten minutes after official sunset during a rapid transition between daylight and darkness. Official weather was scattered clouds at 20,000 feet and 15 miles visibility.

Examination of the wreckage revealed a series of six propeller cuts in the left wing of the SNB, which caused the outer wing panel to separate in flight. The cuts progressed forward from the trailing edge, indicating the Convair's left propeller struck the SNB while passing forward over the wing. The damage pattern showed the Convair closed laterally and vertically at small acute angles, and was actually above and behind the SNB prior to impact. The Board found no evidence of structural or mechanical failure on either aircraft prior to the collision.

The investigation determined that the controller's perception of the aircraft positions was an optical illusion. Flight tests conducted after the accident confirmed that when viewed from a distance at nearly head-on angles in fading daylight, a smaller aircraft appears to be behind a larger one. Because of this error in judgment, the controller believed collision was not imminent when he issued the circling instruction.

The Board believed the SNB crew misinterpreted the controller's traffic information. When they reported having the traffic in sight, they likely saw the TWA Martin, which was landing at that moment, and mistakenly identified it as the Convair.

An engineering study of cockpit visibility showed the SNB crew had a 15-second opportunity to see the Convair while turning onto their base leg. The Convair crew's opportunity to see the SNB began on their base leg, but the Board noted it was improbable they could have seen it from above against the dark terrestrial background. However, during the final approach, the SNB was within visual range and could have been seen by the Convair crew through normal vigilance.

Several witnesses noted the Convair's position and red anti-collision lights were on. Three position lamps from the SNB were examined by the National Bureau of Standards, but filament damage made it impossible to determine if they were illuminated at the time of the collision.

The Board noted that the conflicting approach clearances were broadcast to both crews. Had either crew maintained radio vigilance, the conflicting instructions to follow the same TWA aircraft could have been detected. The Board also believes that the controller should have issued advisory information alerting the crews to the situation, particularly when simultaneous left and right traffic patterns were in use.

### Probable cause

The Board determined that the probable cause of this accident was "a traffic control situation created by the tower local controller which he allowed to continue without taking the necessary corrective action."

The Board found that a contributing factor was "the failure of both crews to detect this situation by visual and/or aural vigilance."