In contrast, the other units at Celle may perform only general maintenance for the Bölkow Bo-105 and Bell UH-1D. At present, other types of aircraft cannot be maintained but only served. The dimensions of the runway generally allow landing and take-off of nearly all existing aircraft. Until now, the largest aircraft to land at and take off from Celle was a Lockheed C-5 Galaxy in 1972. Use Being a military airbase within NATO Celle is generally available for aircraft of the German armed forces, Allied forces and the German Police but restricted by a so-called "PPR" (Prior Permission Request) regulation. This means that pilots intending to approach Celle need a permission prior to departure from their original base. This regulations aims to protect the population living near the airbase from noise pollution made by military aircraft. For arrival and departure of civilian aircraft a prior request and permission in writing or a contract for using the airfield is needed, the exception being aircraft in distress. Additionally to the flying and support units, other military units are based at Celle Air Base, using the military infrastructure but not necessarily need an airfield to perform their tasks. Flying units Aviation Training Centre C Celle Air Base is mainly used as a training airfield for prospective helicopter pilots and therefore part of the German Army Aviation School whose headquarters is in Bückeburg. The training by Army Aviation Training Centre C (Heeresfliegerausbildungszentrum C) is performed on Bell UH-1D and Bölkow Bo-105 and contains the following tasks: training of prospective pilots in simulated emergency situations such as engine failure, autorotation, failure of rear rotor and failure of hydraulic or other systems retraining of pilots who had piloted only other helicopter systems training of prospective flight instructors special helicopter courses training of own pilots disaster relief Following the reorganisation/reduction of the German Armed Forces this unit will be disbanded. Flight support units Geo-Information Service Unit Celle The Geo-Information Service Unit Celle (Geoinformationsberatungsstelle Celle) functions predominantly as the local Met Office of Celle Air Base. The unit is responsible for weather information which is passed on to air traffic control, and weather forecasts for pilots. The unit is permanently on duty even when the airfield itself is closed. Around the clock weather observations are fed into a worldwide data system. Celle Air Base Fire Services Celle Air Base Fire Services (Heeresflugplatzfeuerwehr Celle) is given the task of