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This package was compiled by the FAA Alaskan Region Public Affairs Office in Anchorage and sent to FAA managers with a memo from Paul Steucke dated March 5, 1987. It gathers material on the November 17, 1986 sighting by the crew of Japan Air Lines flight 1628: a news release, pilot and controller transcripts, crew interviews and radar analysis. The FAA concluded that it could not confirm the event. It attributed the second radar target to a split, uncorrelated return from the JAL Boeing 747 and planned no further investigation.
“Gordon”20 pages
ANALYSIS OF UNCORRELATED PRIMARY AND BEACON TARGETS (JAL-1628, 11 / 17 / 86 AKST) Approximately 61 minutes of data was extracted from the EARTS CDR printouts relating to the November 18 incident involving JAL-1628 and the alleged UFO sighting. Review of the data involving this incident did not show any abnormalities that could be associated with any type of target as indicated by the pilot of JAL-1628. Radar returns from the aircraft and surrounding terrain vary with the different segments of the flight, but are considered normal for the area. Returns relating to the incident can be categorized as three types: primary radar reinforced by a beacon reply (primary radar returns and beacon returns are both evident in the same 1/4 mile range cell), beacon only reply and beacon with an associated radar reply. Seventy-two percent of the replies were radar with beacon reinforcement (same range cell) which is normal for the Murphy dome radar system. Approximately 25 percent were beacon only and of those that registered as beacon only, 90 percent of those had a primary only reply within 1/8 of a mile, either ahead or behind the beacon target (5 behind, 12 ahead). Th ese uncorrelated primary returns are not uncommon, due critical timing associated with the delay adjustments aircraft transponder for beacon systems and the correlation circuitry within the radar equipment. to the in the target Whe n an aircraft is being interrogated as it passes through the beginning of adjacent range cells the intricate timing between t h e t wo systems very often is off just enough to declare both a beacon and a radar target in different range cells, resulting in uncorrelated radar replies. Th e data derived from the JAL-1628 flight is representative of t h e data from another aircraft in the same general area and is con s i dered normal. February 25, 1987 -us .'"Dennis R. Simantel ZAN-AAL-ARTCC
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