A Proximity Alert was the event that a Hovercraft was discovered by Sentinel. A loud shrill alarm would sound to alert the crew, in particular the ship's Captain, Operator, or On duty Redpill. In the event that the alarm was raised while crewmen where jacked into the Matrix the Hovercraft's Operator and all Human born crewmen would then be forced to do one of three things: call all jacked in crew members back to the Real World, activate the ship's Electromagnetic pulse destroying all machines in the area and killing all jacked in crew, or be forced to wait and hope that the ship is not detected. Many ship Captains would find fleeing or powering down a more effective way of survival than risk using shipboard weaponry.