The Traffic alert and Collision Avoidance System (TCAS) is intended to serve as a backup, redundant system that alerts and advises the pilot when all other methods of aircraft separation assurance fail. A flight simulator experiment examined pilot responses to TCAS advisories in a full air traffic environment. This paper discusses two analyses of the pilots' use of information within their environment. The first analysis examined air traffic communications manipulated according to four conditions: traffic call-outs, instructions conflicting with the TCAS advised avoidance maneuver, the ability to over-hear relevant partyline information, and no relevant communications. The second analysis used data from an eye tracker to identify when the pilot examined the traffic situation display provided by TCAS. These patterns of information use are then compared with pilot compliance to the Resolution Advisories provided by TCAS.