This subsystem works with the TBAD system of the LBT through a delay unit and the laser interlock hardware. When the TBAD system detects an air plain it sends a signal to the delay unit. This unit sends the signal to aircraft avoidance service (basdard) which has 2 seconds to nicely pause the AO system and stop laser propagation. Due to time constraints, this basdard is connected directly (and not via its subsystem controller) to the aircraft avoidance interface of the arbitrator. If the software fails to stop laser propagation within the mentioned time, the laser interlock is activated, closing the laser shutters.