Prior Permission Request. In aviation, you normally need to obtain permission before landing at an airfield. To do so, a PPR form needs to be completed and the information given to the airfield in advance of your arrival. You'll need to tell them things like your time of arrival, aircraft type, whether you require fuel, how long you'll be staying, your aircraft's callsign etc.

The PPR is normally a formality, but an airfield would be perfectly within its rights to refuse permission to land.