Red-alert

red-alert

   red-alert
   Causes Red Alert status in a mission. This function ends the current mission, and moves to the next mission
   in the campaign under red alert status. There should only be one branch from a mission that uses this expression.
   Takes no arguments.

Comments

Despite what the SEXP description says, red-alert has been tested with a simple branching campaign and it appears that you can branch off of a red-alert mission.

Regardless, red-alert missions often cause errors in retail and SCP FreeSpace, so avoid them if it all possible. This can be done using campaign-persistent variables to "remember" the status of various craft just before the player departs.

If you want to make a red-alert occur as the player jumps out, create an event that waits for the player to hit ALT+J. Chain to it an event that causes the red-alert to occur once the ship has reached jumpout velocity (40 m/s) to give the red-alert a few seconds to go into effect.