High Quality Content by WIKIPEDIA articles! Automatic Independent Surveillance - Privacy (AIS-P) is a data packet protocol for the TailLight system of aircraft Traffic Collision Avoidance, wherein a single Mode S 64 microsecond message is transmitted by an aircraft ATCRBS or Mode S transponder, and received by aircraft and Air Traffic Control on the ground. This is an augmentation to aircraft transponders which states aircraft position and velocity in such a way as to minimize interference with any other avionics system, maximize the possible number of participating aircraft, while not relying on any equipment on the ground, and protecting aircraft from potential attack. AIS-P and ADS-B are competing protocols for aircraft based surveillance of traffic, a replacement technology for Mode S radar and TCAS.