ALLEGED INTRUSION OF PRC AIR SPACE

• Document Type: CREST
• Collection: Library of Congress
• Document Number (FOIA) /ESDN (CREST): LOC-HAK-110-10-1-6
• Release Decision: RIPLIM
• Original Classification: S
• Document Page Count: 5
• Document Creation Date: January 11, 2017
• Document Release Date: February 25, 2010
• Sequence Number: 1
• Publication Date: June 9, 1972
• Content Type: MEMO

No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
OSD Review Completed
SANITIZED
COPY
FOLLOWS
ON-FILE NSC RELEASE
INSTRUCTIONS APPLY
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
25X1
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
25X1
?,
flEC No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
Astrity
.14,400k, Date 4,,=.34-0/
fr.,?.../tomprommoomosmoovi....woss
'4004,,kaougoord0
SECRET
THE SECRETARY OF DEFENSE
WASHINOTON. 0 C. 20301
"
9 JUN 'WW2
MEMORANDUM FOR THE DEPUTY ASSISTANT TO THE PRESIDENT
FOR NATIONAL SECURITY AFFAIRS
SUBJECT: Alleged Intrusion of PRC Air Space
This is in reply to your request for a written investigative repot
concerning the alleged intrusion on 4 June 1972 of four tl.S. military
aircraft into the airspace of the Peoples Republic of Chula in the
vicinity d'Ping Hsiang, K.wang Si Province.
Three strike flights of four F-4 airc:raft,each, aleng with a number
of escort aircraft, struck the Northeast Railroad and a nearby high-
way segment during the period of the alleged violation, However, a
review of aircraft flight paths, aircrew procedures, flight monitoring
systems and available intelligence indicates that there was no violation
of the PRC border.
The strike flights which penetrated North Vietnam during the period
of the alleged violation began their ingress by overflying two prominent
island checkpoints off the coast of North Vietnam. The weather
was such as to permit visual recognition a these initial checkpoints,
and in addition, both were excellent aircraft radar checkpoints.
From the second island checkpoint, the strike flights assumed a track
of 309 true course until theY reeetted North Vietnam's Highway 13B,
at which point they proceeded to the target on a course Of 316? for
26N14. Upon, arriving at the Nor theast Railroad, the Strike flights
proceeded southwest and struck their assigned targets.
Throughout the period of ingress to the target area, aircrew rnembers
cross-checked aircraft heading, inertial navigation systems and visual
reference points. The possibility of track error by this number of
aircraft, all with fully operable navigation aids, is virtually nonexistent.
EXEMPT PROM GENERAL DECIASSirICATION
sca*DUX.z OW EXECUTIVE ortncR 11652
EXEMMON CATEGORY
SECRET Sec Dsg 0010t kr,
99
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
Atittalori
Inwriroin, t
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6
SECRET
o.reover a11 aircrew members had been briefed prior to flight on
a ion.
the absolute necessity of avoiding a border v
The flights which conducted the strike in North Vietnam during
period of the alleged violation were accompanied by escort airc
whose ftnuttion was to protect the strike force from enemy fighters.
The escort aircraft were under posi.ti,ve radar control throughout the
ogress and egress of North Vietnam, and the radar controllers confirm
that these aircraft at no time approached the MC border.
Certainairborne and shiphorne radar facilities also monitor all
US air traffic over North Vietnam for the purpose, inter alia, of
?issuin varnings when border violations are imminent. Warnings of
PC are,broacleast over emergency frequencies monitored by all
ots, and they include a suggested egress heading which will guide
aircraft in question away from, the border. No warnings were
ued to any of the aircraft overilyin.g North Vietnam during the
period of the alleged violation.
In addition to the facts disc ed above, inteiligence sources ?
that Chinese radar tracking often. has been in error. Radar is
particularly likely to provld? erronepus information when there
eeneiderable roeuntainous terrain between the tracking station and the
radar target, as was the case when the alleged violation occurred.
In sum y all availableevidence indicates that the claimed border
violation did not occur, and that Chinese radar tracking error was
the most likely cause of this incident,
No Objection to Declassification in Part 2010/02/25: LOC-HAK-110-10-1-6