1959 — May 12, Capital Airlines Flight 75 disintegration in storm, near Chase, MD — 31

— 31 AirDisaster.Com. Accident Database. Accident Synopsis 05121959.
— 31 CAB. AAR. Capital Airlines…Vickers…Viscount…Near Chase, MD, May 12 1959.
— 31 Kimura. World Commercial Aircraft Accidents 3rd Ed., 1946-1993, V.1. 4-11-1994, p.3.6.

Narrative Information

Civil Aeronautics Board: “Synopsis About 1613, May 129 1959, Capital Airlines Flight 75 disintegrated in flight over an area near Chase, Maryland. All occupants, 4 crew and 27 passengers, were killed. The aircraft, a Vickers-Armstrongs Viscount, N 7463, was destroyed.

“From all of the available evidence the Board believes that the inflight disintegration was caused by aerodynamic loads imposed on the aircraft which exceeded its design strength and which were generated by an excessive airspeed combined with turbulence and maneuvering loads. Based upon the evidence the Board concludes that there was a loss of control in extreme turbulence in the area of thunderstorms and, after a steep involuntary descent during the subsequent recovery, loads beyond the design strength of the aircraft occurred.

“Following the preparations for Flight 75 Capital Airlines dispatch had received additional weather information affecting the route of flight. This information was the first that delineated the location of a potential squall line along the route and indicated that the severity of thunderstorms along the line was increasing. Although it was known that Flight 75 did not have the assistance of operable radar no action was taken by dispatch to ensure that the flight had received this information. The Board considers this information would have been valuable to the flight.

“Investigation On May 12, 1959, Capital Airlines Flight 75 was scheduled from La Guardia Field, New York, to Atlanta, Georgia, departing at 1500 and arriving at 1755…. At 1610 the flight advised, “Ah, Washington Center, this is Capital 75, we’ve reduced to one seven zero knots account rough air.” This was the last message from the flight on the center recorders and the last which could be determined as having been made.

“According to the evidence. just prior to the disintegration the aircraft was flying southwest at an altitude estimated as between 3,000 and 7,000 feet. A majority [of witnesses] believed it was flying in a straight and level attitude and at a normal speed. At the time of disintegration it was in a clear area between clouds and near large thunderstorm buildups….

“The main wreckage was located about 2 miles northeast of Martin Airport near Chase, Maryland. The area is 49 nautical miles from the Westchester…. The heaviest portions of structure were found concentrated in a localized area showing an instantaneous breakup of most of the aircraft, although many lighter and smaller pieces were drifted by northwest winds and deposited along a southeast path about 2-1/2 miles long. Some of this latter structure fell into swamp and heavily wooded areas and some into shallow inlets of Chesapeake Bay. An exhaustive search, greatly assisted by several civil and military organizations, resulted in recovery of about 90 percent of the aircraft structure which was then moved to a hangar, laid out, and given meticulous examination….

“The fuselage broke up in flight into three principal sections. These, in general. were the cockpit and forward passenger cabin, the cabin rearward to the last row of seats, and the aft fuselage from the last row of seats to the area below the vertical stabilizer. Much of the fuselage shell and overhead structure tore away in small pieces. These were found scattered over the full 2-1/2-mile long wreckage path….

“The wreckage was…examined for evidence of a lightning strike. It was not possible to conclude that lightning did not strike the aircraft; however, it was conclusively established that there was no significant damage to the aircraft as a result of a lightning strike….

“Autopsies were performed on all of the crash victims according to provisions of the law of the State of Maryland. At the public hearing the Chief Medical Examiner testified relative to the findings in order that the Board could avail itself of every facet of information relevant to the accident. The findings indicated that all of the occupants of the plane were killed by impact with the ground, although about 20 passengers had sustained ante-mortem injuries. The majority of the ante-mortem injuries were described as scalp injuries of the type and degree which suggested heavy bumps on the head by contacting overhead structure. Others were seat belt injuries and two or three suggested forces applied downward on the body forcing it into the passenger seat. The findings showed that some passengers were exposed to an intense flash fire which contained droplets of flaming liquid. At least 10 passengers revealed an elevated level of carbon monoxide; the highest was about 10 percent, not normally a disabling amount. The medical Examiner said the time required to attain the levels found was difficult to determine. Depending on several factors. the time could vary from eight seconds to several minutes. He indicated that the relatively few bodies showing carbon monoxide was consistent with a short period of exposure during which some passengers were affected while others in the immediate area were not. The medical findings indicated none of the persons was struck by lightning….

“At 1415 the Idlewild Weather Bureau office issued the following flash advisory. “Line of scattered thunderstorm activity near Martinsburg-Harrisburg-Poughkeepsie northeastward is moving eastward about 20 knots accompanied by severe turbulence and conditions locally below 1,000, visibility 2 miles. This line will move to near Providence-New, York City-Philadelphia by 1800 increasing in intensity during afternoon. Valid until 1815.” The Capital meteorologist located in Washington marked off the areas covered by the advisory on a blackboard chart located on one wall of the dispatch office. The advisory was also available on the teletypes at the dispatch sectors positions in the office.

“During the afternoon radar reports were issued about hourly from Andrews AFB weather. These reports described the locations of the thunderstorms and indicated they were increasing in intensity during the afternoon along the New York Washington route of Flight 75. These reports were also on teletype machines located in Capital dispatch at the sector positions.

“About 1548 the cold front passed the Baltimore-Chase area. It was indicated by a pronounced wind shift in about two minutes, a pressure jump of .08 inches of mercury in 20 minutes, and wind gusts to about 45 knots. According to the Civil Air Regulations and the Capital Airlines Operations Manual, dispatch may cancel or divert a flight on the basis of existent or anticipated adverse weather conditions. The captain of a flight has this authority and under emergency conditions may take such action as he considers necessary in the interest of a safe operation. Dispatch is also required to furnish the en route pilot any additional available information concerning meteorological conditions which may affect the safety of a flight.

“No action was taken by dispatch to furnish the flash advisory or radar information to Flight 75. Dispatch did not know if Captain Paddack had received the advisory prior to departure. It was stated by dispatch personnel that they believed the flash advisory indicated improved conditions over those previously forecast and that all of the weather data indicated the thunderstorms were scattered. thus circumnavigable….

“Following the accident a study of the weather conditions prevailing in the accident area at the time of the accident was made by a U. S. Weather Bureau research meteorologist. The results of this study showed there were large rapidly developing thunderstorms in the vicinity of Martin Airport, located about 2-1/2 miles southwest of the accident area. Utilizing several techniques it was also determined that extreme turbulence 3 most probably existed at 14,000 feet in the thunderstorm cells and areas around them. It was also shown that extreme turbulence may exist not only in the thunderstorm cell but up to five miles around it.

“Analysis On the basis of all the available evidence it is the Board’s analysis that the inflight disintegration occurred as the result of loads imposed on the aircraft which exceeded its design strength. It is the Board’s opinion that the forces were from a high indicated airspeed in turbulence. The Board believes that this airspeed was generated during an involuntary descent from 14,000 feet which followed loss of control of the aircraft in extreme turbulence. The Board is convinced that no preexisting weakness or condition contributed to the breakup and that no malfunction or failure of the aircraft, its systems or its components led to the circumstances under which the disintegration occurred….

“Because Flight 75 was released at 1435 with 1400 weather attached to the release and because the crew was apparently at the aircraft considerably before flight time, the Board believes that Captain Paddack did not receive the 1415 flash advisory. While the flight was en route no action was taken to ensure the flight had this information or to provide it with available radar information concerning thunderstorms along the route. The advisory would have delineated the position and movement of the line of thunderstorms along the route and would have indicated that they were expected to increase in intensity. Radar information could have indicated the individual positions of the thunderstorm. While it is not possible to state the action Captain Paddock would have taken had he received the information the Board believes it would have supplemented substantially what he could see, thus providing him with more information on which to base his decisions. Certainly, according to the carrier’s operations manual, this information fitted the description of information which should be furnished a flight.

“Conclusions From all the evidence the Board concludes that Flight 75 deviated at the Westchester omni to circumvent thunderstorm which were visible on the airway of intended flight. At 14,000 feet and at reduced airspeed a course of about 240 degrees was followed which closely paralleled a line of thunderstorms associated with a cold front. The Board concludes that the flight penetrated an area of extreme turbulence in the immediate vicinity of a severe thunderstorm which resulted in loss of control of the aircraft. This resulted in an involuntary descent during which high airspeed was generated. Aerodynamic loads from the airspeed, recovery, and turbulence then exceeded the design strength of the aircraft, causing it to disintegrate….

“The Board fully recognizes that there are many factors in adverse weather phenomena that are difficult to assess accurately. The Board has therefore advocated every practical assistance to pilots transporting the public. The Board believes that aircraft radar has proved to be such an assistance, particularly in modern high-performance aircraft. While it is impossible to predict precisely the action which would have been taken by the captain had the airborne radar been operable, there is evidence to indicate the likelihood that the area of turbulence could have been avoided through the use of airborne radar. The Board therefore concludes that the provision of airborne radar on such aircraft would enhance aviation safety.

“The Board determines that the probable cause of this accident was a loss of control of the aircraft in extreme turbulence resulting in an involuntary steep descent following which aerodynamic loads from high airspeed, recovery, and turbulence exceeded the design strength of the aircraft.” (CAB. Capital Airlines…Vickers…Viscount…Near Chase, MD, May 12 1959.)

Sources

AirDisaster.Com. Accident Database. Accident Synopsis 05121959. Accessed at: http://www.airdisaster.com/cgi-bin/view_details.cgi?date=05121959&reg=N7463&airline=Capitol+Airlines

Civil Aeronautics Board. Aircraft Accident Report. Capital Airlines, Inc., Vickers-Armstrongs Viscount, N7463, Near Chase, Maryland, May 12 1959. D.C.: CAB, 23 Oct 1959, 11 p. At: http://dotlibrary1.specialcollection.net/scripts/ws.dll?file&fn=8&name=*P%3A%5CDOT%5Cairplane%20accidents%5Cwebsearch%5C051259.pdf

Kimura, Chris Y. World Commercial Aircraft Accidents 3rd Edition, 1946-1993, Volume 1: Jet and Turboprop Aircrafts. Livermore, CA: Lawrence Livermore National Laboratory, Risk Assessment and Nuclear Engineering Group. 4-11-1994.