The name of the airbase is never mentioned. However at one ponint Nick views a press clipping that states the (presumed) hit-and-run driving incident occurred in the village of Brandon. That's in Suffolk, adjacent to the US airbase at RAF Lakenheath. (However, the building Nick is seen parked outside when he asks, and is denied, permission to visit the base commander, is not at Lakenheath, it looks more like RAF Uxbridge which would have been easier to get permission to film at, and is also very close to the Shepperton studio where the film was made.)