It depends on the level of altertness an "Alarmrotte" has. That can range from 5 to 15 minutes from "beeing on the ground" to "flying to destination".

If you look at this map of German airforce bases, one of the biggest is in Cologne (Köln-Wahn), so its no surprise that they were this quick

http://www.luftwaffe.de/portal/a/luftwaffe/start/team/stan/!...