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This FAA Alaskan Region Public Affairs Office release, dated March 5, 1987, is a computer printout of recorded FAA radar data for Japan Air Lines Flight 1628 on November 17, 1986. It covers 38 minutes of computer time and lists 105 radar returns. Of these, 86 are usable and 19 are uncorrelated primary returns. The printout records when the pilot first asked about other traffic and when he said he could not see the UFO. It also explains that uncorrelated returns occur when the primary and beacon signals do not match in position.
“Japan Air Lines Flight 1628”3 pages
Read from the scan by GLM-OCR; expect the odd misread word.
An "uncorrelated primary and beacon(secondary) return on a radar screen occurs when the radar energy that is sent up toward the aircraft (primary signal) returns off the surface of the aircraft at a slightly different moment than the beacon (secondary) transponder signal and the two do not match up as being at the same place or same computer radar cell.
Document, cited by the archive. The PDF is mirrored here; the original link is above. The text was read from the page images by GLM-OCR; expect the odd misread word. 179 pages are in the text index: search them above, or from the library's search.