American Airlines Flight 327

American Airlines Flight 327

An American Airlines Convair CV-240, similar to the aircraft involved
Accident
Date	January 6, 1957
Summary	Controlled flight into terrain
Site	Near Tulsa, Oklahoma, US
Aircraft
Aircraft type	Convair CV-240-0
Aircraft name	Flagship Mount Vernon
Operator	American Airlines
Registration	N94247
Flight origin	T. F. Green Airport in Providence, Rhode Island
Stopovers	Logan Airport in Boston LaGuardia Airport in New York City Hancock Airport in Syracuse, New York Rochester Municipal Airport in Rochester, New York Willow Run Airport in Detroit Midway Airport in Chicago Lambert Municipal Airport in St. Louis Springfield Municipal Airport in Springfield, Missouri Joplin Municipal Airport in Joplin, Missouri
Destination	Tulsa Municipal Airport, Tulsa, Oklahoma
Passengers	7
Crew	3
Fatalities	1
Injuries	7
Survivors	9

American Airlines Flight 327 was a scheduled flight between T. F. Green Airport in Providence, Rhode Island and Tulsa Municipal Airport in Tulsa, Oklahoma, with intermediate stops in Boston, New York City, Syracuse, New York, Rochester, New York, Detroit, Chicago, St. Louis, Springfield, Missouri, and Joplin, Missouri. On January 6, 1957, the Convair CV-240-0 performing the flight crashed during an instrument approach to the Tulsa Municipal Airport, killing one of the occupants and injuring seven. Weather conditions in the area were poor, and the aircraft descended through dense clouds and fog. As it approached the runway, it flew lower than the intended path and crashed into the ground 3.6 miles (5.8 km) north of the approach end of the runway. The probable cause of the crash was determined to be the captain's lack of alertness in allowing the first officer to continue an instrument descent to an altitude too low to permit terrain clearance.

Background

Flight 327 was a regularly-scheduled flight between T. F. Green Airport in Providence, Rhode Island and Tulsa with intermediate stops at Logan Airport in Boston, LaGuardia Airport in New York City, Hancock Airport in Syracuse, New York, Rochester Municipal Airport in Rochester, New York, Willow Run Airport in Detroit, Midway Airport in Chicago, Lambert Municipal Airport in St. Louis, Springfield Municipal Airport in Springfield, Missouri, and Joplin Municipal Airport in Joplin, Missouri. It was operated by American Airlines using one of the company's 40-passenger Convair CV-240 twin radial engine aircraft. The airline had operated this type of aircraft on its short-haul routes between 1948 and 1964.

On January 5, 1957, The scheduled flight's first legs between Providence to Chicago were uneventful, but its takeoff was delayed as maintenance technicians in Chicago worked on a problem with the plane's fire alarm warning system, that caused the warning flights to blink and the warning bell to ring. Technicians repaired the problem, and outbound flight to St. Louis left one hour and forty minutes late. The flight crew reported that the previous issue did not occur again after the repairs. The aircraft departed Joplin at 11:23 P.M. Central Standard Time, en route to Tulsa, with seven passengers, two pilots, and one flight attendant.

Accident

At 11:47 P.M., as the flight approached Tulsa, the crew contacted the Tulsa approach controller, who reported the weather conditions that included a ceiling of 600 feet (180 m), a visibility of 2.5 miles (4 km), very light drizzle and fog, and calm winds.. As the aircraft approached the airport, the crew asked the controller if they should expect any delays, and were told that the only local traffic was then making an ILS approach. Shortly after that, the controller advised the flight that the visibility had dropped to 1.75 miles (2.8 km) and that the United States Weather Bureau was checking the ceiling. He asked if the pilots would prefer the Owasso straight-in approach to runway 17, or if they would prefer an ILS approach, and the pilots responded that they would make the Owasso approach. At midnight, the flight was cleared to land on runway 17L. Two minutes later, an updated weather report was transmitted to the flight, giving a measured ceiling of 200 feet (61 m), visibility 1.75 miles (2.8 km) and very light drizzle and fog. This transmission was not acknowledged by the pilots and all other attempts to contact the flight were unsuccessful. At one minute after midnight on January 6, crashed into a hillside west of Owasso, Oklahoma, 3.6 miles (5.8 km) north of the approach end of the runway.

The aircraft first hit the top of a tree, then it hit the ground, leaving deep tire marks and marks from the propellers in the ground. The landing gear collapsed and the aircraft slid along the ground, jumped a ravine, and finally came to rest 540 feet (160 m) from the initial point of impact. The aircraft came to rest under a high voltage power line, leaking aviation fuel, but there was no fire. The wings were ripped loose of the aircraft, and the engines torn off and found near the main wreckage. The nose section of the fuselage was crushed, and both pilot seats in the cockpit were torn from their sliding tracks., There was substantial damage to the rest of the fuselage, including buckling of the structure in the cabin area, distorting the cabin floor, causing seats to detach. There was no fire after the crash.

The accident was the first fatal accident that American Airlines had experienced since August 1955, when American Airlines Flight 476, also operated by a Convair 240, crashed while attempting to make an emergency landing in Fort Leonard Wood, Missouri, killing all 30 occupants.

Aftermath

After the crash, the passengers and crew were able to open two of the three exits on the aircraft and evacuated, except for one badly injured passenger who was pinned inside the plane and unable to get out. The copilot exited from the side window of the cockpit.

The copilot of the plane and one of the passengers separately left the accident scene to seek help. The two were picked up by a vehicle that had been driving towards the hill after seeing lights on it. The air traffic controller, having lost contact with the aircraft, notified the Oklahoma Highway Patrol that the plane was missing and asked them to check out the area near the Owasso checkpoint. Ambulances and emergency equipment arrived and transported the occupants of the aircraft to two hospitals in the area.

The Civil Aeronautics Board (CAB) sent two investigators to Tulsa to lead the investigation alongside local officials. The officials met with officials from American Airlines to set up teams in various areas of investigation and later announced that team members had been forbidden to talk with reporters until the investigation was complete.

That injured passenger, a 70-year-old woman from Tulsa, ended up dying from her injuries. One of the injured passengers was released from the hospital in the days following the crash, but the rest remained for a week or more.

Aircraft

The aircraft was a Convair CV-240-0 piston aircraft, serial number 104, registered as tail number N94247. Construction had been completed on October 7, 1948. Named "Flagship Mount Vernon", it had been flown for a total of 18,062 hours. It was powered by two Pratt & Whitney R-2800 Double Wasp 18-cylinder engines.

With a capacity of 40 passengers, American Airlines's Convair CV-240 fleet was used on short-haul routes, and the company placed an initial order for 100 of the aircraft in 1946, later reduced to 75. The company promoted the speed of the performance of the aircraft, offering the same speeds and climb rates as the 52-passenger, 4-engine Douglas DC-6 aircraft the company used on its long-haul routes. It was slated as a replacement of company's aging fleet of Douglas DC-3 aircraft.

Passengers and Crew

The flight carried seven passengers and three crew members, all residents of the United States. One of the passengers died in the crash and the remaining passengers were hospitalized.

The captain of the flight, Wesley G. Mims, was 35 years old. He had been employed with the company for near fourteen years. At the time of the accident, he had a total of 8,655 flying hours, including 4,100 hours in Convair aircraft. He suffered cracked ribs and severe facial cuts in the crash. The first officer, 34-year-old Paul H. Johnson, had been employed with American Airlines since June 1946. At the time of the crash, he had a total of 2,170 flying hours, including 924 in Convair aircraft. He suffered severe bruises and rib fractures in the crash, and could not remember anything that happened immediately before the accident.

Investigation

In the immediate aftermath, CAB officials stated that they expected the investigation into the crash to take about a week. They quickly ruled out the possibility of mechanical failure and the aircraft was cut up for scrap metal and American Airlines officials estimated that the wreckage would be cleared from the site on January 11th.

The CAB held two days of public hearings in Tulsa starting on February 27, 1957.. During the hearings, the board heard testimony that the altimeters on the plane may have been defective. The CAB safety investigator who headed the probe testified that the captain's altimeter read −200 feet (−61 m) when it should have read zero, and the co-pilot's altimeter read 220 feet (67 m) when it should have read 647 feet (197 m). However, the investigator could not make any statement of whether the altimeters were functioning correctly before the crash. Captain Mims testified that after the flight from St. Louis to Springfield, he noticed that his altimeter read −100 feet (−30 m) on the ground when it should have read zero, but that he forgot to report the incident. Company regulations required corrective actions before takeoff when such inaccuracies are noted. Captain Mims testified that during the last flight, the flight crew had double checked the plane's two altimeters against each other several times during the flight. After receiving approach clearance, he said he extended the landing gear and instructed Johnson to descend at a rate of 1,000 feet (300 m) per minute.

During the flight, the first officer's altimeter was adjusted to show elevation above mean sea level, whereas the captain's altimeter was set to show the elevation above the Tulsa airport ground level of 674 feet (205 m) above sea level. Captain Mims testified that he last recalled observing a reading of 700 feet (210 m) on his altimeter just before the crash.

The first officer, Paul Johnson, testified that he and the captain had taken turns flying each of the legs on the flight, and on the leg between Joplin and Tulsa, it was the first officer who was in command of the aircraft. The day's flight had been the first time that Mims and Johnson had flown together, and it was also the first time Johnson had flown an instrument approach into Tulsa. The investigation revealed that the crew had originally reported to work at Tulsa at 8:50 A.M. on January 5, and that they had been on duty for fifteen hours on the day of the crash.

On March 7, 1957, the CAB suspended the flying permits of Captain Mims for six months, stating that even though First Officer Johnson had been flying the aircraft at the time of the crash, it was the Captain's responsibility to supervise the flight, and said that the captain had been careless in listening to the first officer as he conducted the landing approach. The suspension meant that Mims could continue to fly as a first officer, but not as a captain.

In January 1958, the CAB released its final report. It concluded that a "lack of alertness" on the part of Captain Mims probably caused the plane crash. It said that Mims permitted the aircraft to be flown too low to clear the terrain in the area. The investigation concluded that it was likely that when Mims instructed the first officer to descend to 700 feet (210 m), he was not clear that he meant 700 feet above ground level, which would have been read on the captain's altimeter, or 700 feet above sea level, which would have been indicated on the first officer's altimeter. A descent to 700 feet above sea level would have placed the aircraft at or near ground level. The investigators faulted the captain for his failure to notice that the aircraft descended below the minimum safe altitude in time to prevent the crash.