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As the captain of TW 42 sighted the other aircraft, he also believed he was on a collision course with it, made an immediate right bank and pulled back on his yoke. He testified that he realized the bank to the right would not allow his aircraft to pass clear of the other aircraft and he attempted to reverse the direction of bank and pushed the yoke forward. There was insufficient time for the aircraft to react to this central reversal and the aircraft's left wing, outboard of the No. 1 engine, struck the right horizontal stabilizer of EA 853.
The flight recorder data indicate that approximately 13 seconds prior to impact, TW 42 was maneuvered in a manner which produced a +2.5 "g" load. This time period correlates with the testimony of the TW captain that as he sighted EA 853, it assumed a climbing attitude, and the TWA captain rolled into a right bank, and pulled back on the yoke. This is compatible with the time required for EA 853 to climb the thousand feet or portion thereof, separating the two aircraft. The left wing of TW 42 sliced through the right horizontal stabilizer of EA 853 from a point near the leading edge of the right hand vertical fin and horizontal stabilizer exiting near the center of the trailing edge of the elevator. The swath through the stabilizer formed a relative angle of 12 degrees forward of the stabilizer rear spar.
The Board does not have sufficient information to determine the exact pitch, roll, and yaw attitude in reference to the horizon of each aircraft at the time of the collision. However, the scuff marks and break-up pattern indicate a collision angle of 74 degrees between the longitudinal axes of the two aircraft. By plotting the geometries of the impact angle With the heading of TW 42 established from the flight recorder readout as approximately 139 degrees, it was determined that EA 853 was on a heading of 213 degrees and at an approximate airspeed of 140 knots.
Flight test data from the Lockheed L-1049C test flight and data supplied by the aircraft manufacturer indicate that the expected decay of airspeed from the estimated 210 to 215 knots cruise speed of EA 853 during a rapid pullup of 1,000 feet would result in airspeed of from 130 to 150 knots.
As TW 42 passed under and toward the rear of EA 853 the No. 1 engine cowling and a portion of the left wing of the former struck the underside of the main fuselage of the latter. This impacting tore out the hydraulic boost package and the control cables to the rear empennage of EA 853, effectively rendering the elevator and rudder flight controls inoperative.
The pilots' abilities to effect visual separation in the short time of visual contact provided insufficient response time for collision avoidance. Analysis of the cloud conditions, the positioning of the two aircraft, and the reactionary evasive maneuvers attempted, left no opportunity for a frame of reference to the horizon. The up-slope effect of the cloud coverage resulted in a misjudgment by the crew of EA 853 of their altitude separation, the resultant evasive maneuver, and the subsequent reactionary evasive maneuver by TW 42 ended in collision.
2.2 Conclusions
(a) Findings:
1. Both aircraft crewmembers were properly certificated and trained for the operation involved.
2. TW 42 was properly certificated, maintained, and dispatched for the flight.
