USAF CONUS Gap-Filler Radar Sites
(AN/FPS-14 and AN/FPS-18), 1957 - 1970

"During the late 1950s another area of progress was the development and deployment of AN/FPS-14 and AN/FPS-18 gap-filler radars. Having a range of around sixty-five miles, these radars were placed in areas where it was thought enemy aircraft could fly low to avoid detection by the longer-range radars of the permanent and mobile radar networks. Gap-filler radar deployment peaked in December 1960 at 131 sites throughout the continental United States. Because the introduction of gap-filler radars alleviated the need for civilians to scan the skies for enemy bombers, the ADC disestablished the Ground Observer Corps on January 31, 1959."

Searching The Skies
USAF Air Combat Command
June, 1997

AN/FPS-18 site layout

The radome pictured here is located in Great Falls Nike Park in Herndon / Dranesville, VA, alongside Utterback Store Road. This Air Force gap-filler radar radome was not actually associated with this former Army Nike-Ajax missile facility (site # W-83L), and how the radome came to be here apparently is not known to present-day park officials in Fairfax County. It is also unknown where this radome was formerly used. However, it is definitely an Air Force gap-filler radar radome, and still has an Air Force serial number (not shown) stenciled on the inside. The radome is situated within the earthen berm where the missiles were once fueled. Panels were cut away on either side of the radome to allow kids to play inside. An eerie echo may be heard inside.

In the USGS aerial image above, from the "TerraServer" website,, the old Air Force gap-filler radar radome is the round white object immediately to the left (east) of the baseball diamond. The Nike earthen berm is the brownish, tree-covered area around it to the east and south.

Here's an excerpt from a newspaper article about Montana gap-filler installations.

Here's a news clipping on gap-filler diesels

Adding a radome to a gap-filler

Photos below contributed by Don Horton

Manned Gap Fillers

[Click to download 185KB PDF file]