CASE FILE US-1986-001

Japan Air Lines Flight 1628 Events

17 November 1986 · Interior Alaska, along the Fort Yukon–to–Anchorage air corridor · Location generalized (Regional) · US

Official finding

"Unable to confirm object" — the FAA's investigation did not identify what the crew reported; radar anomalies recorded during the encounter were attributed by investigators to possible split or beacon radar returns and clutter, without ruling out other causes.

Federal Aviation Administration

Federal Aviation Administration records — Japan Air Lines Flight 1628 (17 November 1986)

Anomaly Index assessment

Unresolved: insufficient data

Radar coverage of the reported encounter was sparse and inconsistent across the systems available that night, with most returns either absent, momentary, or later attributed by the FAA to clutter or split beacon artifacts rather than a confirmed independent target. Only the JAL1628 crew reported a sustained visual sighting; a nearby United Airlines flight and a military aircraft diverted to the area reported seeing nothing unusual. A celestial misidentification (Jupiter and Mars, both above the horizon in the reported direction) has been proposed and is plausible for at least part of the sighting, but it does not fully account for the captain's description of sustained close-range pacing, and the public record does not contain the corroborating instrumented data needed to resolve the discrepancy.

Anomaly Index assessments are editorial evaluations of the public record. They are not official government determinations.

Unresolved means that the available evidence does not support a reliable identification. It does not imply extraterrestrial or nonhuman origin.

What was reported

On 17 November 1986, Captain Kenju Terauchi and the crew of Japan Air Lines cargo flight 1628, en route from Reykjavik to Anchorage over interior Alaska, reported two small lighted objects that approached from below and paced the Boeing 747 in close formation for an extended period, followed by what Terauchi described as a much larger object that remained visible at a distance. Terauchi reported feeling heat from the objects and requested clearance to maneuver away from them; Anchorage Air Route Traffic Control Center relayed the reports and coordinated with military radar facilities. First Officer Takanori Tamefuji and Flight Engineer Yoshio Tsukuba corroborated seeing lights but were less certain than Terauchi that the lights were not stars or reflections. Air traffic controllers stated that a radar target appeared intermittently in the aircraft's vicinity on at least one ground radar display and briefly on a military radar at Elmendorf Air Force Base, though the two systems did not produce a consistent, corroborated track. No other aircraft in the area, including a nearby United Airlines flight and a U.S. Air Force aircraft that responded to the area, reported seeing anything unusual.

What is verified

The JAL1628 crew reported unidentified lights near their aircraft to Anchorage Air Route Traffic Control Center on 17 November 1986.[1]
The FAA opened a formal investigation, interviewed the crew, and compiled a case file including radar-facility statements and internal analysis memoranda.[1]
Radar returns associated with the reported objects were brief and inconsistent across the ground and military radar systems available that night.[1]
A nearby United Airlines flight and a U.S. Air Force aircraft diverted to observe the area reported no unusual sightings.[2]
Jupiter and Mars were both above the horizon in the general direction Terauchi described at the time of the sighting.[2]

Evidence ledger

Evidence items documenting this case
Type	Description	Originality	Source organization	Released	Raw or edited	Metadata	Provenance	Known limitations	Source
Official document	FAA case-file records on the incident, including radar-facility correspondence, crew interview summaries, and internal analysis of the radar returns.	Original	Federal Aviation Administration	1986-1987	Unknown	Partial	Compiled by the FAA during its investigation; released in full to researcher John Greenewald after a multi-year FOIA process and mirrored on the Internet Archive as public-domain records.	Some material was reported destroyed or unavailable at the time of the original FOIA requests; the surviving file documents the FAA's internal handling more thoroughly than it resolves what the crew saw.	[1]
Radar	Intermittent primary radar returns recorded near JAL1628's position by Anchorage ARTCC and, briefly, by U.S. Air Force radar at Elmendorf Air Force Base.	Derivative	Federal Aviation Administration; U.S. Air Force	1986-1987 (described in FAA case file)	Unknown	Partial	Radar-facility logs and controller statements summarized in the FAA case file; original raw radar tapes are not confirmed to survive.	Returns were sporadic, did not form a consistent independent track, and were attributed by investigators to possible clutter or split beacon returns rather than confirmed as a discrete target.	[1]
Eyewitness account	Captain Kenju Terauchi's detailed account of objects pacing the aircraft, including descriptions of light color, apparent distance, and perceived heat.	Original	Japan Air Lines	1986-11-17 (reported); elaborated in later interviews	Unknown	No	Given to Anchorage air traffic control at the time and to FAA investigators afterward; expanded in media interviews in subsequent years.	The first officer and flight engineer described a less detailed and less certain sighting than Terauchi; Terauchi had reported two earlier unrelated sightings, one of which was later attributed to diffused ground lighting.	[2]

Proposed explanations

Celestial misidentification (Jupiter and Mars)

Proposed by Philip J. Klass (aviation journalist and UFO skeptic)

Supporting: Jupiter was roughly 10 degrees above the horizon in the direction Terauchi first reported the lights, which Klass argued could appear to an experienced pilot to be at cruising altitude; Mars was also in the vicinity.

Contradicting: Terauchi described objects that maneuvered, paced the aircraft at close range for an extended period, and produced perceptible heat — details not explained by a fixed celestial object.

Plausible

Radar clutter and split or beacon returns

Proposed by Federal Aviation Administration investigators

Supporting: The intermittent, non-repeating character of the ground and military radar returns is consistent with known clutter and beacon-splitting artifacts rather than a discrete, independently maneuvering target.

Contradicting: Investigators did not rule out other causes, and the returns coincided in time and rough position with the crew's visual reports, which some researchers argue is a stronger correlation than clutter alone would predict.

Plausible

Unidentified craft pacing the aircraft

Proposed by Captain Kenju Terauchi

Supporting: Terauchi's detailed, consistent core narrative and his professional experience as a pilot are cited by proponents as weighing against a simple misidentification.

Contradicting: No independent aircraft, ground observer, or reliable instrumented record corroborates a discrete maneuvering object; the first officer and flight engineer's accounts were markedly less certain.

Disputed

Why this classification?

This case is classified as Unresolved: insufficient data because the available radar record is too sporadic and internally inconsistent to confirm or rule out a discrete object, the sighting rests substantially on a single crew's visual account without independent aircraft corroboration, and more than one conventional explanation remains plausible for different parts of what was reported without fully accounting for all of it.

What remains unknown

Whether any additional military radar data from the encounter beyond what appears in the released FAA file still exists.
Why the first officer and flight engineer's accounts differed significantly in detail and confidence from the captain's.
Whether the reported perceived heat from the objects can be explained by cockpit conditions or was solely subjective.

Classification history

1987
Unable to confirm object; investigation closed without identification — Federal Aviation Administration
1987
Likely celestial misidentification combined with radar clutter — Philip J. Klass / Committee for the Scientific Investigation of Claims of the Paranormal
Independent skeptical assessment, not an official government finding.
2023
Full FAA case file released to the public after a multi-year FOIA effort — The Black Vault (FOIA release)
2026
Unresolved: insufficient data — Anomaly Index
Editorial assessment; see index_assessment.rationale and dossier.why_classification.

Sources

Primary source: Tier A
Federal Aviation Administration records — Japan Air Lines Flight 1628 (17 November 1986) (opens in new tab)Federal Aviation Administration, U.S. Department of Transportation · 1986-1987 (FAA investigation records)
Source provenance note
Public-domain FAA case-file records concerning the 17 November 1986 sighting reported by the crew of Japan Air Lines cargo flight 1628 over Alaska, including radar-facility correspondence, crew interview summaries, and internal FAA analysis memoranda. Obtained through a multi-year FOIA effort by researcher John Greenewald (The Black Vault) and mirrored in full on the Internet Archive as public-domain U.S. government records. A partial scan of the same file set also circulates via NICAP (nicap.org/docs/861117_flight1628.pdf).
Credible secondary source: Tier B
What Really Happened to Japan Airlines Flight 1628 in 1986? (opens in new tab)The Debrief · 2021-06-07
Source provenance note
Investigative journalism piece synthesizing the FAA case file, contemporary radar-system limitations, and skeptical analysis (Philip Klass) alongside Captain Terauchi's account. Used here for narrative context and to cross-check details in the primary FAA file; it does not independently qualify the case for inclusion.