Reconstruction of Pan Am Orleans accident

An improved technique has been developed for reconstructing the trajectory of an aircraft based upon the analysis of five channel flight data recorder (FDR) information. The FDR data of heading, indicated airspeed, pressure altitude, and load factor are combined with engine thrust, aircraft aerodynamic data, and the boundary conditions for the trajectory in order to solve the lift and drag equations of the aircraft. In reconstructing aircraft wind shear accidents, the trajectory of the aircraft, the horizontal wind field, and pitch time history of the aircraft can be determined uniquely. If factors other than wind shear are present that may potentially influence aircraft aerodynamics performance, such as wing ice or rain induced aerodynamic roughness, then both wind shear and roughness penalties can be calculated by imposing additional constraints on the trajectory. The reconstruction technique has been applied to the Pan Am accident in New Orleans July 1982 in which both wind shear and heavy rain were present. Three scenarios were considered—wind shear only, aerodynamic penalties due to heavy rain only, and a combination of wind shear and lift loss and drag increase due to heavy rain. It is suggested that the latter scenario gives results that are most consistent with other evidence concerning the accident.