 Volunteer observers at the surrounding Royal Observer Corps posts were specially trained and provided with coloured rocket flares (Code named "Granite") to guide any aircraft lost in thick fog towards the limited number of FIDO equipped stations.The only other airfields in Lincolnshire fitted with FIDO systems were RAF Fiskerton, RAF Ludford Magna and RAF Sturgate and there were only 15 FIDO stations in the UK, mostly on the east coast.RAF Metheringham was utilised in the developmental testing of the experimental programme to assist aircraft landing in foggy conditions (the system eventually known by the acronym FIDO) and the station featured in the official RAF training film.