UAP and UFO Glossary: The Terms, Programmes and Cases Explained
Plain-English definitions of the terms used in UAP reporting: AARO, AATIP, UAPTF, transmedium, Nimitz, GIMBAL, Project Blue Book and more.
- AARO
The All-domain Anomaly Resolution Office: the US Department of Defense office set up in July 2022 to investigate unidentified anomalous phenomena. It collects reports from military and now some civilian sources, analyses sensor data, and reports to Congress.
AARO succeeded the UAP Task Force and an earlier Pentagon office. It states that it has found no verifiable evidence of extraterrestrial technology, while acknowledging that some cases stay unresolved for lack of data.
What the Pentagon’s UFO office has actually found · Official site
- AATIP
The Advanced Aerospace Threat Identification Program: a Pentagon programme run from 2007 to 2012 that studied reported UAP encounters, funded with around $22 million secured by Senator Harry Reid.
AATIP became public knowledge in 2017, when the New York Times reported on it alongside the release of three Navy videos. Parts of its work continued under later offices.
- All-domain
A term now built into official language: anomalies are considered wherever they appear, in the air, in space, on or under the sea, not only in the sky.
- Anomalous
In official use, “anomalous” means the report does not match what sensors or witnesses expect — not that it has been shown to be extraordinary. Most anomalies resolve into ordinary objects or incomplete data.
- Belgian UFO wave
A series of reports across Belgium between November 1989 and April 1990, mostly of large triangular formations of lights. The Belgian Air Force released its investigation files and F-16 radar recordings in 1990.
The wave is often cited on both sides of the debate: witnesses and radar recorded something, while investigators pointed to misidentified aircraft, planets and police vehicles.
- Blue Book, Project
The US Air Force’s longest-running UFO study, operating from 1952 to 1969 at Wright-Patterson Air Force Base. It examined 12,618 reports, of which about 700 remained unexplained.
Blue Book’s 1968 close-out report, prepared with the University of Colorado (the Condon Report), concluded that further study was unwarranted. The files are now public through the US National Archives.
- Close encounter
A classification system introduced by astronomer J. Allen Hynek in 1972: “close encounter of the first kind” is a sighting within about 150 metres; the second kind leaves physical traces; the third kind involves reported beings.
- Condon Report
The 1968 University of Colorado study of UFOs, formally titled “Scientific Study of Unidentified Flying Objects” and led by physicist Edward Condon. Its conclusions that the phenomenon deserved no further study shaped the closure of Project Blue Book.
- Crash retrieval
The claim, made publicly and under oath by former intelligence officer David Grusch in 2023, that the US government operates a decades-long programme to recover and reverse-engineer craft of unknown origin.
Grusch has not publicly provided evidence for the claim, and AARO’s 2024 historical review reported finding no verifiable evidence of such a programme. It remains a claim, not an established fact.
- FLIR, GIMBAL and GOFAST
Three videos recorded by US Navy fighter aircraft sensors, released officially by the Pentagon in April 2020. They show objects tracked by infrared cameras; the Navy confirmed the footage was genuine but did not characterise what the objects were.
Independent analysts have proposed conventional explanations for each video, including line-of-sight error, parallax and atmospheric effects. The debate over them is a good example of why sensor context matters.
- GEIPAN
The Groupe d’Études et d’Informations sur les Phénomènes Aérospatiaux Non-identifiés: the French space agency CNES office that investigates UAP reports and publishes its case database openly, including a classification of each case by how well it is explained.
GEIPAN’s public database is one of the best open resources for comparing how national programmes classify sightings.
- GEPAN
The predecessor of GEIPAN, founded in 1977 as the Groupe d’Études des Phénomènes Aérospatiaux Non-identifiés — the first government office anywhere dedicated to systematic UFO investigation.
- Gimbal video
A 2015 US Navy infrared video from the US East Coast in which pilots react to an object that appears to rotate. Analysists disagree about whether the rotation is real or an artefact of the camera’s internal optics.
- Halt memo
Lt. Col. Charles Halt’s January 1981 signed memorandum “Unexplained Lights”, written for the UK Ministry of Defence, documenting the Rendlesham Forest events of December 1980. It is one of the few primary military documents in the field.
- Interstellar object
A small body detected passing through the Solar System on a path that indicates it came from outside it. Two have been confirmed: ‘Oumuamua in 2017 and Comet 2I/Borisov in 2019. Claims about earlier interstellar objects remain contested.
- Line-of-sight error
The most common reason a moving object seems to perform impossible manoeuvres. If something crosses your field of view at a steady speed, its apparent direction and speed change wildly without it turning at all.
This effect explains many “instant acceleration” reports, and is a leading explanation for behaviour in some Navy videos. It needs no exotic physics — only a viewer without a fixed frame of reference.
- MUFON
The Mutual UFO Network: a civilian membership organisation founded in 1969 that trains volunteer field investigators, mostly in the United States. Its case database is searchable by members.
MUFON is independent of any government. Its quality varies by region, as it depends on volunteers.
- Nimitz incident (the “Tic Tac”)
The November 2004 encounter off San Diego in which US Navy F/A-18 crews from the aircraft carrier Nimitz tracked and chased an object described as smooth, white and roughly the size of a combat jet, moving between altitudes at speed. The FLIR1 infrared video of the encounter was released officially in 2020.
Commander David Fravor and Lt. Cmdr. Alex Dietrich were among the pilots who reported it. Radar operators aboard the Princeton also tracked objects over several days.
- NUFORC
The National UFO Reporting Center: a civilian reporting database founded in 1974 and based in Washington State. Anyone can submit a report, and its tallies are widely used as a rough measure of public interest.
NUFORC counts are unverified submissions, so spikes in them usually reflect news coverage as much as sky activity.
- Phoenix Lights
The mass sighting of 13 March 1997 across Arizona and parts of Nevada and the Mexican state of Sonora: a slow-moving V-formation of lights seen by thousands, followed later that night by flares dropped by Maryland Air National Guard A-10s training over the Barry M. Goldwater Range.
Investigators treat the two events separately: the earlier formation remains disputed, the later flares are explained.
- Preliminary Assessment (ODNI, 2021)
The June 2021 Office of the Director of National Intelligence report on 144 military UAP reports mostly from 2004–2021. It identified one case with confidence as a large deflating balloon and concluded that the rest needed better data.
- Project Sign, Grudge and Blue Book
The three consecutive US Air Force UFO studies: Sign (1947–1949), Grudge (1949–1951) and Blue Book (1952–1969). Together they examined thousands of reports and produced the bulk of the early US government record on the subject.
- Robertson Panel
A 1953 CIA-convened group of scientists that reviewed Blue Book data. It concluded the cases posed no direct threat but recommended public education to reduce the reporting of panic-prone incidents.
- SETI
The Search for Extraterrestrial Intelligence: the scientific effort to detect signals from other civilisations, usually by radio telescope. SETI studies the sky; UAP investigations study individual reports — the two are separate fields that rarely overlap.
- Transmedium
A term used in official reports for objects alleged to move between domains — air, space and water — without apparent difficulty. It describes a claimed capability, not an established one.
- UAP
Unidentified Anomalous Phenomena: the term US government agencies use instead of UFO. It covers anything observed that cannot be immediately identified — in the air, in space, at sea or underwater.
The change of name was partly about dropping the cultural baggage of “flying saucer”. It does not imply a single phenomenon, and officials are explicit that most reports resolve to ordinary objects.
- UAP Task Force (UAPTF)
The US Navy-led task force established in 2020 to study UAP reports, the successor to a Pentagon programme revealed in 2017 and the predecessor of AARO.
- UFO
Unidentified Flying Object: an object observed in the sky that cannot be identified at the time by the observer. Most resolve to aircraft, satellites, planets, meteors or balloons once checked.
The term carries decades of cultural weight, which is why official use shifted to UAP. On Track the Unknown, “UFO” simply means “not yet identified”.
- USO
Unidentified Submerged Object: the marine counterpart of a UFO report — something seen in or emerging from water. The 1967 Shag Harbour incident in Nova Scotia is the best-known example.
- Witness corroboration
Independent accounts from separate witnesses of the same event at the same time. Corroboration is the single most useful element in a sighting report, and the reason to point it out to anyone nearby while it is still in the sky.