Document · 25 September 2019
Estimating Flight Characteristics of Anomalous Unidentified Aerial Vehicles (Knuth, Powell & Reali, Entropy, 2019)
Also known as Entropy paper, Knuth paper
A physics paper that treats the reported motions of unidentified craft as data. For four cases (a 1951 airliner encounter near Bethune, the 1986 Japan Air Lines sighting over Alaska and the 2004 Nimitz encounters, from Kevin Day's radar account, David Fravor's sighting and the ATFLIR video) it works out how fast the objects must have accelerated to do what witnesses and sensors describe, using deliberately conservative assumptions so that each figure is a lower bound. The estimates run from about 70 g to well over 5,000 g, far beyond any aircraft or missile, with no sonic boom or heat that such energies should produce.
Its estimates are only as good as the observations: the Nimitz radar figures rest on Day's recollection, not on the radar data, and the masses are assumed. It draws on the Scientific Coalition for UAP Studies' longer forensic report on the Nimitz encounter, of which Powell and Reali were among the authors.
Sources: the paper (Entropy 21(10), 939, open access)
Facts and claims
- documented Published in the peer-reviewed journal Entropy on 25 September 2019 by Kevin Knuth (University at Albany) with Robert Powell and Peter Reali of the Scientific Coalition for UAP Studies, it estimates lower bounds on the accelerations of craft in a handful of well-documented encounters: “Estimated accelerations range from almost 100 g to 1000s of gs with no observed air disturbance, no sonic booms, and no evidence of excessive heat commensurate with even the minimal estimated energies.” Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- documented From Kevin Day's account of radar returns dropping from 28,000 feet to sea level in 0.78 seconds, the paper finds a most probable acceleration of about 5,370 g; assuming a mass of 1,000 kg, the object would have reached about 46,000 mph, some 60 times the speed of sound, and needed a peak power of about 1,100 GW, more than ten times the United States' total nuclear power output. Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- documented The radar figures come from Day's recollection, not from the radar data, which the authors did not have: “Without detailed radar data, it is not possible to know the acceleration of the UAPs as a function of time as they descended to the sea surface”; they estimate a lower bound instead. Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- documented From David Fravor's account that the Tic Tac was gone within about a second, and the limits of human eyesight, it estimates a lower bound with a most probable acceleration of about 150 g and a mean of about 550 g. Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- documented Fitting models to the object's position in the Nimitz ATFLIR video, the best model has it accelerating at about 75.9 ± 0.2 g for about 0.53 seconds; the authors note that it “may have accelerated and decelerated erratically multiple times”. Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- documented For the object that paced Japan Air Lines flight 1628 over Alaska in 1986, it estimates 68 ± 7 g (crossing the circle) or 84 ± 8 g (circling the airliner) from the long-range radar track. Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- documented The authors weigh the alternatives: “The extreme estimated flight characteristics reveal that these observations are either fabricated or seriously in error, or that these craft exhibit technology far more advanced than any known craft on Earth”, and say the number and quality of the witnesses and the equipment favour the latter. Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- documented The paper had no external funding. It appeared in a special issue for the MaxEnt 2019 conference, whose organizers, as guest editors, made the decision to publish on the recommendations of three anonymous reviewers. Source: doc-knuth-2019-entropy-flight-characteristics.pdf
- claimed Knuth says he first presented the work at the MaxEnt workshop at the Max Planck Institute for Plasma Physics; the organizers, as guest editors, decided on publication after review by three referees, not he as editor-in-chief. — Kevin Knuth Source: Estimating the flight characteristics of the 2004 Nimitz encounter: SCU panel with Kevin Knuth, Robert Powell and Peter Reali (2021) at 52:15
Connected files
People
- Kevin Knuth (authored by) — Knuth determined the methodology, wrote the software and performed the analysis
- Robert Powell (authored by) — Co-author, with Peter Reali, for the Scientific Coalition for UAP Studies
- Kevin Day (discusses) — The authors thank Day for answering their questions; the radar estimate rests on his account
Incidents
- USS Nimitz “Tic Tac” encounter (analyses) — Estimates the Tic Tac's accelerations from Kevin Day's radar account, Fravor's sighting and the ATFLIR video
- Japan Airlines flight 1628 incident (analyses) — Estimates 68 to 84 g from the FAA radar track of the object around the airliner
Videos
- FLIR1: the Nimitz “Tic Tac” video (official U.S. Navy release) (analyses) — Fits kinematic models to the object's position in the video: about 76 g for half a second
- Estimating the flight characteristics of the 2004 Nimitz encounter: SCU panel with Kevin Knuth, Robert Powell and Peter Reali (2021) (subject of)
- Physicist Kevin Knuth on the Tic Tac's accelerations: Ross Coulthart (NewsNation Reality Check, 2026) (subject of)
Organizations
- Scientific Coalition for UAP Studies (produced by) — Powell and Reali, both SCU board members, co-wrote it, and SCU is an affiliation of all three authors
Mentioned in this file
- Graham Bethune (Person)
- David Fravor (Person)
More documents
- David Fravor — written statement, House Oversight hearing (July 26, 2023)
- Ryan Graves — written testimony, House Oversight hearing (July 26, 2023)
- GEIPAN case file: « AF3532 » Coulommiers, 28 January 1994
- Trud, 30 January 1985: "At 4:10 Precisely" (Aeroflot flight 8352), English translation released by the CIA
- Spanish Air Force file 670603: aircraft and radar encounter over Montánchez, 3 June 1967
- Statement by the Department of Defense on the Release of Historical Navy Videos (April 27, 2020)