The interrogation signal doesn't get aimed either. Depending on many factors, the interrogation signal from the TCAS equipped aircraft could reach aircraft lower than the 'scan' range, which would have your light blinking. And ofcourse, your xponder responding to it, which may or may not be received by the TCAS aicraft (again depending on many factors). Only if it is received, THEN will it be filtered if it is outside the scan range
