TechnicalPc
Collision Probability
The estimated likelihood that two space objects will collide during a predicted close approach, the key metric for deciding whether to manoeuvre.
Collision probability (often written Pc) quantifies the risk that a conjunction between two objects results in a collision, computed from their predicted relative geometry and the uncertainty in each object's position.
Operators compare the Pc reported in a conjunction data message against an action threshold; if it exceeds the threshold, a collision-avoidance manoeuvre is planned. Because Pc depends on covariance, fresher and more accurate tracking data generally yields more reliable decisions.