FIDO – Setting Runways Ablaze to Enable Foggy Airport Operations

In the midst of World War II, after Royal Air Force pilots deftly escaped harrowing dogfights and deadly bombing missions in enemy territory, they often returned to their home airfields only to succumb to impenetrable fog and smoke that made landing impossible. In extreme cases, such conditions forced crews to point their aircraft out toward sea, away from populated areas, and bail out near the beach. Scores of perfectly good aircraft were lost, and something had to be done.

At the time, no instrument landing systems with the necessary precision and reliability to land in extremely limited visibility had been developed. And even if it had, dirty, round-the-clock industrial operations supporting the war effort were generating smog so thick, it reportedly reduced visibility to mere feet. As the continued loss of perfectly functional aircraft was not sustainable, it took some outside-the-box thinking to come up with a workable solution.

Such a solution came from an unlikely source – a government entity known as the Petroleum Warfare Department. Tasked with developing new and creative ways to utilize various flammable fuels as weaponry, the department combined vast amounts of fuel with a variety of ignition and delivery techniques to conduct a wide variety of destructive experiments.

A worker adjusts the flow of fuel to fine tune flame height along the edge of a runway.

Perhaps while experimenting with such weaponry, an intriguing side effect was observed. In conditions of extremely thick fog and smog, intense flames ignited on a large scale effectively dispersed the obscured air, generating clear conditions in the area. British pilot and civil engineer Arthur Hartley then developed a system called Fog Investigation and Dispersal Operation, or FIDO, that permitted a controlled burning of fuel along each edge of a runway, thus improving visibility and enabling incoming aircraft to land safely.

The system utilized massive quantities of fuel. At airfields with longer runways, it consumed nearly a quarter million gallons of fuel every hour. This amounted to 4,000 gallons per minute, or 67 gallons every second. Nevertheless, it was determined that due to the low cost and ample supply of fuel at the time, the number of aircraft saved would be worth the extreme consumption.

The RAF tested initial FIDO operations in 1942, finding that the system was able to lift parcels of dense fog to a height of 80 feet. While this still presented pilots with a challengingly low ceiling with which to contend, the walls of flame lining each runway edge would have enabled them with effective visual guidance to the runway as they flew the final segment of an approach.

fido diagram
An early illustration explains the FIDO system in detail.
fido diagram
Even light winds altered the effectiveness of the FIDO system

FIDO systems were installed and utilized at a number of airfields across England as well as others in France and the western US during WWII. After the war, a few systems were retained for emergency use, but ultimately, far cleaner and more economical solutions such as improved runway lighting and advanced instrument landing systems were developed as a means of enabling flight operations during periods of extremely limited visibility.

FIDO Fog_Investigation_Dispersal_Operations
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