From AMS Glossary
(Or FIDO.) A system for dissipating fog artificially, in which gasoline or other fuel is burned at intervals along an airstrip that is to be cleared of fog.
The name was formed from the four initial letters of the project name: Fog Investigation Dispersal Operations. Fido systems were used at many bomber bases in England during World War II, and commercial transports have been brought into fog-covered airports in the United States using similar methods.