Question: The 1963 Ankara mid-air collision involved an airplane from a company with a head office in what city? 
Sentence (from "Traffic collision avoidance system"): A traffic collision avoidance system or traffic alert and collision avoidance system (both abbreviated as TCAS, and pronounced tee-kas) is an aircraft collision avoidance system designed to reduce the incidence of mid-air collisions between aircraft.
Relevant evidence: No