F.I.D.O. (Fog, Intense Dispersal Of)

The Risk

The long cold winter nights rolled in, this was the time the adverse weather set in.  Bomber crews, Tired after long op’s over enemy territory wading through flak, Searchlights, night fighters and extreme cold.  Then the crews faced another enemy upon their return to England.

There foe now was the cold winter fog!!

Before FIDO

Before the introduction of FIDO, fog had been responsible for losses of a number of aircraft returning from operations. Often large areas of the UK would be simultaneously fog-bound and it was recommended procedure in these situations for the pilot to point the aircraft towards the sea and then, while still over land, for the crew to bail-out by parachute, leaving the aircraft to subsequently crash in the sea. With raids often consisting of several hundred aircraft, this could amount to a large loss of bombers.


The Solution

They needed to find an answer to this problem, and The FIDO system was developed at the department of chemical engineering of the University Of Birmingham.  The invention of FIDO is formally attributed to Dr John David Main-Smith.

Fog Investigation Dispersal Operation, or “Fog, Intense Dispersal Of” FIDO for short.

The system involved pumping petroleum (mixed with alcohol) along a

Continuous line of pipes installed on both sides of the main runway. When

Ignited, huge flames shot into the sky where the resultant heat created a thermal effect, which in turn lifted the fog away from the runway.

When fog prevented returning Allied aircraft from locating and seeing their runways to land, they would be diverted to FIDO equipped aerodromes. RAF night bombers which were damaged on their missions were also diverted to FIDO airfields due to the need to make certain they could land when they arrived. 

How FIDO Works

The device consisted of two pipelines situated along both sides of the runway and through which a fuel was pumped along and then out through burner jets positioned

at intervals along the pipelines. A jeep with a flaming brand lashed to its rear drove fast down both sides of the runway to ignite the fuel at the outlets in the pipes. The burners were sometimes ignited by men on bicycles or by runners on foot, the vapours when lit produced walls of flame.  Now runway could be seen for a great distance from the air.  The heat from the flames evaporated suspended fog droplets so that the Allied aircraft could have suitable visibility to find the airfield and land.

Once an aircraft had landed, the crews could relax whilst their planes would be refuelled and, if needed, repaired before flying back to their normal bases the next day.

The FIDO installation usually stored its fuel in four circular upright tanks built at the edge of the airfield with a low brick bund wall in case of leakage. The tanks were usually encased in ordinary brickwork as protection from bomb splinters or cannon fire.

FIDO used huge quantities of fuel, as much as 100,000 gallons per hour. Over twice this amount was used by airfields with longer runways such as RAF Carnaby. Large fuel storage tanks filled with low-grade petrol and possibly kerosene and other fuel were connected by pumps to provide this fuel to the runway pipes. Although extravagant in the use of fuel consumed, the device more than made up for the costs involved in the reduction in aircraft losses.

Only fifteen airfields would receive this expensive but lifesaving system.

RAF Carnaby and RAF Melbourne where two was of those selected.

Above: Aircraft landing at RAF Graveley using FIDO

Above: A plan of FIDO at RAF Melbourne ©Kenneth Durkin

FIDO Facts

RAF fields equipped with FIDO


RAF Blackbushe / Hartford Bridge

RAF Bradwell Bay

RAF Carnaby – Emergency Landing Ground

RAF Downham Market, Norfolk

RAF Fiskerton

RAF Foulsham

RAF Graveley

RAF Ludford Magna

RAF Manston – Emergency Landing Ground

RAF Melbourne

RAF Metheringham

RAF St Eval

RAF Sturgate

RAF Tuddenham

RAF Woodbridge – Emergency Landing Ground



The last FIDO-equipped airfield at which a system was maintained was RAF Manston, the system being available for emergency use as late as 1952. Due to the high costs involved use had to be reported to the Air Minister.

Initial installation of FIDO was designed and constructed along Runway 1 at London Heathrow Airport but the pipes and other fittings were never installed.