{"type":"events","slug":"1973-cobra-mist-radar-anomaly","title":"Cobra Mist Radar Anomaly","url":"https://disclosdex.com/events/1973-cobra-mist-radar-anomaly","description":"Anglo-American Orford Ness over-the-horizon radar tests in 1973 exposed unresolved clutter-related anomalies and prompted shutdown of the COBRA MIST program.","date":"1973-06-30T00:00:00.000Z","tags":["Radar"],"disclosureRating":6,"status":"unresolved","connectionCount":0,"content":{"markdown":"The Cobra Mist project at Orford Ness was conceived as a high-power Anglo-American over-the-horizon radar program, but its public legacy became the unresolved clutter-noise anomaly documented in declassified technical files.[^1]\n\n## Origin\n\nThe project emerged from early U.S. over-the-horizon experiments and was moved from an initial Turkish option to Orfordness after Turkey declined hosting, when British planners offered a site on the Suffolk coast.[^1][^5]\n\nBy 1966 the Air Force had selected RCA to build the AN/FPS-95 system, classified as a Secret joint Anglo-American operation, with construction beginning in 1967 and operational planning continuing through 1971.[^1]\n\n## Who reported or observed it\n\nAnomalous performance was first documented in the on-site joint program by the Design Verification System Testing (DVST) teams, who reported in late 1972 that a severe “clutter-related noise” occupied range bins where target returns were expected.[^1][^3]\n\nThe anomaly was also seen by the DVST Technical Committee, which then triggered transfer of program control to a civilian scientific director and formation of the US/UK Scientific Advisory Committee (SAC) in January 1973.[^1]\n\n## Narrative evolution\n\nIn December 1972 HQ USAF directed that testing mode change from normal DVST/IOT&E to an investigation of the noise problem because internal hardware remediation had failed to restore required performance.[^1]\n\nThe SAC ran targeted experiments through May 1973 and reported that source elimination remained incomplete, even after expanded hardware checks and environmental testing, though several specific improvements were identified.[^1][^2][^3]\n\nOn 1 May 1973, findings were briefed to US and UK defense leadership; on 29 June 1973 the U.S. and MOD public position announced project termination, and operations were phased out by 30 June 1973.[^1][^4]\n\nAfter deactivation, the radar was dismantled and no operational reuse occurred at that site for surveillance, while the infrastructure shifted to civilian transmission ownership in later decades.[^5]\n\n## References\n\n[^1]: [FOIA documents on the AN/FPS-95 Cobra Mist OTH Radar, Part 1 of 4](https://www.cufon.org/cufon/cobramst.htm)\n[^2]: [FOIA documents on the AN/FPS-95 Cobra Mist OTH Radar, Part 2 of 4](https://www.cufon.org/cufon/cobramst2.htm)\n[^3]: [FOIA documents on the AN/FPS-95 Cobra Mist OTH Radar, Part 3 of 4](https://www.cufon.org/cufon/cobramst3.htm)\n[^4]: [National Archives catalog entry: COBRA MIST (joint US/UK over-the-horizon radar project at RAF Orfordness)](https://discovery.nationalarchives.gov.uk/details/r/C1230794)\n[^5]: [Suffolk Heritage Explorer – ORF 177 Cobra mist](https://heritage.suffolk.gov.uk/monument/MSF34990)","readingTime":"2 min read"},"relatedRecords":[],"citation":{"canonicalUrl":"https://disclosdex.com/events/1973-cobra-mist-radar-anomaly","title":"Cobra Mist Radar Anomaly","publisher":"Disclosdex","retrievedFrom":"https://disclosdex.com/api/v1/events/1973-cobra-mist-radar-anomaly","license":"CC-BY-4.0"},"witnesses":["USAF and RAF operators conducting initial Orfordness trials","Design Verification System Testing technical officers and operators","Scientific Advisory Committee engineers and scientists from the UK and US"],"evidence":["FOIA-released DARPA/USAF correspondence and declassified JDR paper","Internal technical testing records covering radar capability and noise measurements","Site and program records from UK archival and heritage sources"]}