UFOINTEL
Radar Report
Unclassified Complete
733667-001-020-0003
National Archives and Records Administration
Confidence
85%
Credibility
90%
View original document ↗ hosted at the official government source
Intelligence summary
The document discusses the phenomenon of uncorrelated radar signals, specifically detailing the differences between primary radar returns and secondary beacon returns. It includes a diagram illustrating how these signals can appear on a radar screen when they do not match up in time or location.
Tags & topics
Extracted timeline
Jun 15, 1987
Document Date (year hint)
Document Date (year hint) for 733667-001-020-0003
Jun 16, 2026
Ingestion Date
Ingestion Date for 733667-001-020-0003
Jun 16, 2026
Document Record Date
Document Record Date for 733667-001-020-0003
Jun 16, 2026
Update Date
Update Date for 733667-001-020-0003
Entities mentioned
Full document text
798 characters, transcribed via OCR. Errors reflect the source scan. Compare with the original ↗
UNCORRELATED RADAR SIGNALS
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 thah the beacon (secondary) transponder signal and the
two do not match up as being at the same place or same computer radar
cell. |
—_ Vn : f\—
--RADAR COMPUTER CELL, 1/4 MILE-- RADAR CELL
z SAME AIRCRAFT
4 (Crossing Cell)
: . 4
y= Sy
4
a SECONDARY UP
RADAR
a RETURN
3 (Beacon)
! (Transponder)
<,
Vy
PRIMARY
RADAR
RETURN
(Skin-
Surface)
)
4
wy) ’
,
Wi,
4
=PRIMARY RADAR RETURN
(A) =SECONDARY RADAR RETURN
94 FAA
KG
LAA RADAR
=CORRELATED RETURN
(Combined Return)
Drawing by Paul Steucke
March 5, 1987 =UNCORRELATED RETURN