UFOINTEL
Radar Report
Unclassified Complete
733667-001-011-0012
National Archives and Records Administration
Confidence
85%
Credibility
80%
View original document ↗ hosted at the official government source
Intelligence summary
The document discusses the phenomenon of uncorrelated radar returns from aircraft, specifically detailing the differences between primary radar signals and secondary transponder signals.
Tags & topics
Extracted timeline
Jun 15, 1987
Document Date (year hint)
Document Date (year hint) for 733667-001-011-0012
Jun 16, 2026
Ingestion Date
Ingestion Date for 733667-001-011-0012
Jun 16, 2026
Document Record Date
Document Record Date for 733667-001-011-0012
Jun 16, 2026
Update Date
Update Date for 733667-001-011-0012
Entities mentioned
Full document text
813 characters, transcribed via OCR. Errors reflect the source scan. Compare with the original ↗
. -
|
~
— - . ad ~
“ ‘ . «
nn Oe en ees a wo a ome « bt w dp ee wo - ww )
A
5
A
ly
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.
= f\—
-~-RADAR COMPUTER CELL, 1/4 MILE-- RADAR CELL
SAME AIRCRAFT
\ (Cross{ng Cell)
— Ur =i Yy,
RADAR <a,
RETURN
WN
-
-- RADAR CELL, 1/4 MILE--
(Beacon)
(Transponder )
/—
PRIMARY
RADAR
RETURN
(Skin-
Surface)
=PRIMARY RADAR RETURN
=SECONDARY RADAR RETURN
x =CORRELATED RETURN
(Combined Return)
Drawing by Paul Steucke
March 5, 1987 =UNCORRELATED RETURN