The Saber Launcher is homing explosive weapon used by the Doombringer class in Tribes: Ascend. It fires missiles that will seek their target. It appears to be heat seeking, as it can only target airborne enemies and Grav Cycles, Beowulfs and Shrikes (large heat signatures).
To fire, the Saber Launcher must first lock onto a target, which can be either a vehicle or a player in flight. Lock-on takes 3 full seconds. While attempting to lock-on the player must maintain line-of-sight with the target and if that target touches a surface the lock-on timer restarts. Once lock-on has been achieved, the missle may be shot down by the target or obscured by the terrain.
The Saber Launcher can only be fired when locked-on, but it's tracking system will identify potential targets all over the Doombringers field of vision to a certain distance. Even if no targets can be fired upon, this can help identify potential flag cappers and allow the player to call targets to the team even if he has not yet seen them himself.