[SNAFU]

No, that works, but you have to clear the trigger again, after it was triggered.

If you have the following for the trigger:

 if (("RedIntercept1".Equals(shortName) && active) && (CountAIAirplanes(1) <= maxRedAI)) 
          { 
                AiAction action = GamePlay.gpGetAction("RedIntercept1");
                if (action != null)
			MissionTimer1Int.Restart();
			MissionTimer1IntA.Start();			
			GamePlay.gpLogServer(null, "Intercept 1 triggered ", new object[] { }); //Testmeldung
                {
                     action.Do();
                }
                GamePlay.gpGetTrigger(shortName).Enable = false;            
          }

You can clear the trigger again by something like this:

if (MissionTimer1IntA.Elapsed.Minutes >= 30)   			//wieder freischalten des Triggers
    {
	GamePlay.gpGetTrigger("RedIntercept1").Enable = true; 
	MissionTimer1IntA.Reset();					
	GamePlay.gpLogServer(null, "Trigger 1 clear", new object[] { }); 		//Testmeldung
	}