Incident Overview
A DC-10 captain responded to a Traffic Collision Avoidance System (TCAS) alert by executing an aggressive pitch change. During the maneuver, the airplane decelerated, and the captain felt a slight buffet. This resulted in wrinkling of the elevator skins.
ATC and Traffic Situation
Air Traffic Control (ATC) instructed a DC-9 crew to maintain visual separation, and the crew accepted the instruction. The two airplanes were approximately 7 miles apart under night conditions on converging courses. The DC-9 was descending out of 5,000 feet, while the DC-10 was climbing through 3,800 feet. The controller had to repeat instructions to the DC-10 crew, as well as to other crews. One crew informed ATC that their radio transmissions were weak.
Relevant Documentation
Douglas Flight Operation Letter AOL, C1-E60-HHK-L033, dated January 21, 1988, explained probable resultant damage to aircraft components when speed was reduced to buffet speeds indicated on the Cruise Buffet Onset Boundary Chart as presented in the DC-10 Aircraft Flight Manual. It noted that in some cases this buffeting resulted in wrinkled outboard elevator skins. The letter emphasized that speed reduction down to or near the clean configuration stalling speed greatly increased the chance of experiencing elevator damage.