The language around unidentified aerial phenomena has shifted significantly as governments and defense agencies have adopted formal terminology. "UFO" (Unidentified Flying Object) was the common public term for decades, while "UAP" (Unidentified Aerial Phenomenon, or Phenomena) is the term now used in official U.S. government and defense reporting, emphasizing observation over assumption about what an object might be.
Understanding this vocabulary helps readers evaluate footage in the archive on its own terms. Many records describe observations captured by specific sensor technologies — for example infrared and forward-looking infrared (FLIR) cameras — that record heat signatures rather than visible light. Other entries reference declassified United States Navy recordings that are widely known by nicknames such as "Gimbal," "Go Fast," and "Tic Tac," each corresponding to a separate documented encounter.
The definitions below describe terms as they are used in general and official discourse, not as claims about any particular sighting. They are provided as a reference for browsing the archive: each sighting page records only the documented date, location, source, and footage of an event, without asserting its origin or nature.
The All-domain Anomaly Resolution Office was established within the U.S. Department of Defense in 2022 to coordinate investigation of unidentified anomalous phenomena across air, sea, and space domains, succeeding earlier efforts such as the UAPTF. Its remit includes managing reporting channels and producing consolidated reports to Congress.
officialThe Advanced Aerospace Threat Identification Program was a low-profile U.S. Defense Department effort that investigated reports of unidentified aerial phenomena between roughly 2007 and 2012. It was funded at the request of then-Senate Majority Leader Harry Reid and contracted largely to Bigelow Aerospace. Its public profile rose sharply after 2017 media reporting and the subsequent release of Navy FLIR footage.
officialA tranche of nearly 900 — by some counts 972 — previously classified UFO-related documents released by Brazil's National Archives (Arquivo Nacional) ahead of schedule, reportedly confirming a formal Brazilian government UFO program. The release covers decades of sightings, Air Force investigations, and official correspondence, and is the largest single declassification of Brazilian government UFO material to date.
officialForward-Looking Infrared — an imaging technology that detects heat (infrared) signatures rather than visible light, widely used on military aircraft. Many declassified UAP recordings were captured with FLIR sensors, which is why the objects often appear as bright shapes against a darker background.
technologyThe nickname commonly applied to a declassified U.S. Navy FLIR video showing an unidentified object appearing to rotate against the background. Officially acknowledged and released in 2020 as part of a set of UAP recordings.
officialThe nickname commonly applied to a declassified U.S. Navy FLIR video of a low-altitude, fast-moving object tracked over the ocean. Released in 2020 alongside other officially acknowledged UAP recordings.
officialSpeeds of roughly Mach 5 and above. In UAP reporting, objects described as hypersonic are reported to travel or maneuver at velocities well beyond the performance of known conventional aircraft, often without visible propulsion or sonic signature. Reported speed alone is not proof of anything extraordinary, as estimation of speed and altitude from a single camera is notoriously unreliable.
technologyA portion of the electromagnetic spectrum below visible light, perceived as heat. Infrared sensors detect the thermal radiation emitted by objects, allowing aircraft and other craft to be tracked at night, through cloud, or against a cold sky background. Much declassified UAP footage is infrared imagery, which is why objects often appear as bright blobs rather than detailed shapes.
technologyThe apparent change in the position or motion of an object caused by a change in the observer's position. Parallax is one of the most common sources of misinterpreted UAP footage: an ordinary distant aircraft, filmed from a moving vehicle, can appear to hover, accelerate, or vanish relative to the background when the camera moves.
generalA detection system that transmits radio waves and measures the reflections from objects, used to determine range, bearing, and often velocity. Air-traffic and military radar have produced a large share of the instrumented UAP record, including the 1952 Washington events and many Navy air encounters, because radar records an object's motion even when no visual confirmation exists.
technologyServiço de Informação de Objetos Não Identificados — Brazil's historical unidentified-object investigation effort, which evolved out of the Brazilian Air Force's longstanding UFO record-keeping. SIOANI and its predecessors are among the bodies whose case files appear in the declassified Brazilian National UFO Files.
officialThe nickname for an encounter reported by U.S. Navy pilots in 2004 involving a white, oblong object likened in shape to the breath mint. Associated with the Nimitz carrier strike group and widely cited in public UAP discussion.
officialAn object observed moving between different media — typically from air into water, or vice versa — without an apparent loss of control. 'Transmedium' is used in official U.S. reporting criteria to describe a reported capability that, if genuine, would indicate technology beyond publicly known aerospace systems.
phenomenaUnidentified Aerial Phenomenon — the term used in official U.S. government and defense reporting for an observed aerial object or phenomenon that cannot be readily identified. It emphasizes the recorded observation itself rather than any assumption about what the object is or where it came from.
officialThe Unidentified Aerial Phenomena Task Force was a U.S. Navy-led Department of Defense unit formalized in 2020 to standardize the collection, reporting, and analysis of UAP encounters, particularly those near military training airspace. It issued an unclassified preliminary assessment in 2021.
officialUnidentified Flying Object — the long-standing public term for an aerial object that could not be identified, popularized in the mid-20th century. Largely superseded by 'UAP' in official and scientific contexts.
general