Daniela Toman, Gütersloh airfield tour guide, said: "Once the phone lines open group bookings sell out within 30 minutes – visits are always on a Saturday and individual tickets are usually gone in four hours.
"At first it was a huge surprise for those of us involved. We didn’t know what to expect. We had a feeling there would be interest but weren’t sure."
The base started life as a Luftwaffe base in the 1930s, with evidence of its past still standing.
A huge ground-level compass contraption which pilots would have used to set their own compasses remains - believed to be one of the only two surviving examples.
There is also an airfield museum with aircraft that once flew from Gütersloh on display.