The Defence Intelligence Staff report titled Unidentified Aerial Phenomena in the UK Air Defence Region is dated December 2000.1 The Ministry of Defence later released the report in response to a Freedom of Information request.2
The Buoyant-Plasma Hypothesis
The report's executive summary attributes many UAP reports to meteorological, astronomical, and other familiar causes.1 For a remaining set of observations, it proposes naturally occurring buoyant charged bodies in the atmosphere as a possible explanation.1
The proposed model was used to explain reported lights, rapid apparent motion, and abrupt directional changes.1 The report presents the model as an assessment drawn from available reports rather than direct physical measurement of a UAP.1
Radar and Defence Implications
The executive summary states that atmospheric plasmas could produce radar returns and be mistaken for solid targets.1 It treats possible military applications as a subject for further research.1
Pilot Safety and Conclusions
The report concludes that the available UAP information had no significant Defence Intelligence value and did not indicate a threat to the United Kingdom.1 Its recommendations advise aircrew who encounter an unusual phenomenon against attempting to outmaneuver it, apart from placing it behind the aircraft when possible.1