TAB A
“FLATHEAD EVENT
OPERATION REDWING
1, The FLATHEAD Shot was fired at 06264, 12 June 1956 on a barge
Jocated approximately one-half mile South of YUROCHI Island (DOG) in the
BIKINI Atoll.
The cloud reached an estimated 60,000 feet.
The lower
portion of the cloud and stem moved to the West at approximately 15 knots.
2.
The fallout forecast for FLATHEAD was calculate
on the basis
TWO fallout mumary on H+] Day indicated the fallout sector as 2400
through 0504 extending 100 miles with probable hotline on bearing 010°
with an average intensity on the surface of the water of 1 mr/hr.
The
plus 18-hour summary gave same sector with hot line definitely fixed on
bearing of 310°.
Program TWO surveys confirmed the fallout forecast to be
within the acceptable error of forecasting.
3.
DNA
Cloud penetration aircraft reported the middle and upper portion
of the cloud moving to the northeast at Ht] Hour.
The cloud contimed tc
move in a general north-northeasterly direction throughout H+t3 Hours.
h.
The aerial monitoring (P2V aircraft) reported the ENYU (NAN) air
strip te be free of debris and radiological hazards.
Based on survey
information Reentry Hour was established at 0830M, 12 June.
The initial
helicopter survey at H+3 hours reported fallout still occurring over the
reef and lagoon in the wicinity cf YUROCHI (DOG).
—FTY Jif siveEn S0a—hert
In general, the initial