EFFECTS OF WEATHER ON TACTICAL AIR OPERATIONS OVER NORTH VIETNAM AND LAOS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP84-00825R000100090001-6
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 43
• Document Creation Date: December 9, 2016
• Document Release Date: February 22, 2001
• Sequence Number: 1
• Publication Date: April 1, 1966
• Content Type: REPORT

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DIRECTORATE OF, INT,II~r
Approved, For` Release 2001/08114 ":" ClA-RDP.84-0QO.25 0 00
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This material contains information affecting
the National Defense of the United States
within the meaning of the espionage laws.
Title 18, USC, Secs. 793 and 794, the trans-
mission or revelation of which in any manner
to an unauthorized person is prohibited by law.
GROUP 1
EXCLUDED FROM AUTOMATIC DOWNGRADING
AND DECLASSIFICATION
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FOREWORD
This report, prepared in the Office of Basic Intelligence, describes
and assesses seasonal weather conditions in North Vietnam and Laos
and the effect of those conditions on tactical air operations. Tactical
air operations, in this sense, include low-level aerial reconnaissance
as well as low-level bombing and combat air support and supply. For
the most part the report is not pertinent to high-altitude operations,
nor is it suitable for use in support of specific air operations. Data
used are derived from climatological observations made over a period
of many years and, therefore, constitute averages. Individual weather
conditions may vary suddenly and considerably from the norm.
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EFFECTS OF WEATHER ON TACTICAL AIR OPERATIONS
OVER NORTH VIETNAM AND LAOS
Summary
The monsoonal airflows that control weather conditions in Southeast
Asia are strongly affected by terrain barriers such as the Chaine
Annamitique that separates Laos from North Vietnam and South Vietnam.
Different weather conditions, accordingly, prevail in different parts
of Laos and North Vietnam.
From mid-May to mid-September, low closely packed clouds sweep out
of the southwest, dumping torrential rains and limiting air-to-ground
visibility over Laos. Air-support operations may have to be curtailed
during this period. Across the Chaine Annamitique in North Vietnam,
conditions are only slightly better for tactical air operations. Cloud-
iness still prevails and operational conditions are fair at best.
From mid-October to mid-March, when prevailing winds are out of the
northeast, the contrast in climatic conditions is more pronounced. Through-
out Laos and in northwestern North Vietnam skies are frequently clear and
tactical air operations can be planned with relatively little fear of
interference from the elements. In the rest of North Vietnam, however,
the crachin -- a low and continuous cloud cover accompanied by drizzly
rain -- prevails during the latter part of the period and operations
requiring air-to-ground visibility may not be possible for days at a
time.
In general, the most favorable periods for tactical air operations
in the various regions of North Vietnam and Laos are mid-October to mid-
March in Laos and northwestern North Vietnam; mid-September to mid-October
in the rest of northern North Vietnam; and mid-March into August in
southern North Vietnam.
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I. General Climatic Background*
North Vietnam and Laos have a tropical monsoon climate characterized
by two major seasons -- that of the southwest monsoon, usually prevailing
from mid-May to mid-September, and that of the northeast monsoon, usually
prevailing from mid-October to mid-March. These major seasons are sepa-
rated by two short transitional periods -- the autumn transition, from
mid-September to mid-October, and the spring transition, from mid-March
to mid-May. This seasonal alternation of wind direction controls almost
every aspect of the weather, with marked local variations determined by
the situation of mountain ranges, especially the Chaine Annamitique,
which lies at right angles to both monsoonal airflows and which forms
most of the border between North Vietnam and Laos.
During the southwest monsoon, warm moist air sweeps in from the
Indian Ocean, bringing frequent precipitation to the region. Much of
this summer precipitation is intercepted by the southwest-facing slopes
of the Chaine Annamitique. Rainfall is heaviest on the exposed mountain
slopes in eastern Laos, but even the leeward coastal areas to the east
receive some moisture. The northern part of North Vietnam receives
considerable precipitation during the southwest monsoon from winds that
after crossing the Chaine Annamitique turn northward and pick up moisture
from the Gulf of Tonkin before flowing back in over the land.
In contrast to the ocean-born southwest monsoon, the northeast mon-
soon originates over central Asia and reaches the region after traversing
the southern part of China. At this time of year, relatively dry condi-
tions prevail over much of the region. The southern part of North Vietnam
is an exception. This area receives heavy precipitation during autumn
and early winter from the moisture accumulated as the northeast monsoon
passes over the Gulf of Tonkin. Again, the C:haine Annamitique acts as a
barrier to these moist winds but at this season receives most of the
precipitation on its east-facing slopes.
North Vietnam and Laos are tropical regions, and temperatures and
humidities are high all year. A slightly cooler period is experienced
in the north during the northeast monsoon season, but this is only a
relative change from the sultriness of the other seasons. Temperatures
are still high, and humidities are often very oppressive. Low temper-
atures are experienced only in the higher mountains, where they may drop
below freezing.
II. Effects of Weather on Tactical Air Operations
Weather conditions over most of North Vietnam and Laos limit the
conduct of air operations throughout most of the year. No season experiences
* For data on weather conditions in this area, see Tables 1 through 3.
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long periods of clear weather. Cloudiness, low ceilings, fog, and generally
poor air-to-ground visibility are the chief limiting factors. Other phe-
nomena that adversely affect air operations are widespread thunderstorms
and associated turbulence, typhoons, and a period of persistent low overcast
with fog and drizzle that is known locally as the crachin (from the French
word cracher, to spit). Of lesser significance are such conditions as
icing and clear air turbulence.
The most serious limitation is the prevalence of numerous low clouds
and fog and the resultant low ceilings and poor air-to-ground visibility.
Cloudiness prevails throughout the year in most of the region, with only
moderate seasonal fluctuations. Diurnal variations in cloud cover are
probably greater than seasonal variations, and, at certain hours of the
day at any season, relatively clear conditions may exist over a target
for a short time. In many cases, this is a definitely local condition,
and the need for timely information on the current conditions of visibility
over a specific target complicates operational planning. These spotty
local conditions may also influence the selection of the route to and from
a target. If time over the target is critical, the weather en route becomes
a serious factor because it may make detours necessary. Poor visibility
en route also makes it difficult to spot ground checkpoints needed for
navigation. Fog and low ceilings are common and seriously limit low-level
operations. It is hazardous to attempt to fly under low clouds because of
the mountainous terrain. In general, visibility is much better at high
altitudes than at low altitudes.
Thunderstorms occur most frequently during the southwest monsoon
season and in spring, commonly about midday. Most such storms are fairly
short but extremely violent and must be skirted by aircraft in flight.
Severe turbulence is experienced in and around thunderstorms, particularly
during the spring transition season. Thunderstorms often may interfere
with a mission either by obscuring a target or by necessitating long
detours en route to or from the target area.
Occasionally a typhoon may interfere with air operations for a few
days. Such typhoons originate in the South China Sea and may strike the
coast of North Vietnam at any time between July and late November but
are most common in August, September, and October. The direct passage
of a typhoon will force cessation of all air operations. Sometimes a
typhoon that approaches but does not strike the coast of North Vietnam
interferes with air operations. Although 18 typhoons reached the general
area of North Vietnam in the period 19+7-56, only 5 were of typhoon
intensity by the time they reached the coast. The typhoon season in the
South China Sea extends from May into January, but by late November the
track of typhoons usually is too far south to affect North Vietnam.
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The prolonged spell of crachin weather occurs in North Vietnam from
about December through April. This period of light rain or dull and
gloomy drizzle is accompanied by low stratus clouds, mist, and fog,
although the total amount of precipitation usually is small. The crachin
affects air operations seriously, especially operations below about
8,000 feet, because of its limiting effect on air-to-ground visibility,
its widespread character, and its seasonal persistence. Once the crachin
season begins, it dominates weather conditions in North Vietnam until
well into the spring.
Icing conditions and turbulence not associated with thunderstorms
or other convective activity are not serious limiting factors for air
operations in Laos and North Vietnam, but some upper-air turbulence may
be expected. Aircraft icing may occur between 15,000 and 25,000 feet
during the southwest monsoon season, when the air is laden with moisture,
but it can be avoided by flying a few thousand feet higher or lower. Most
of the turbulence experienced over the region is associated with thunder-
storms and other convective activity.
A. Region A -- Laos and the Highlands of Northwest North Vietnam*
1. Southwest Monsoon Season (Mid-May to Mid-September)
This is a poor season for air operations -- the moisture-
laden southwest monsoon brings much cloudiness to Laos. The land, which
gradually rises eastward, presents an upslope to the southwesterly air-
stream and, together with the normal processes of convection, causes a
general lifting of the air. Conditions are poorest in the southern half
of Laos, where the monsoonal flow of air has a tendency to pile up
against the Chaine Annamitique and form dense masses of cumulus and
cumulonimbus clouds. In the north the clouds are less dense because the
originally wet winds have lost some of their moisture as they traveled
long distances over the land. A normal daily pattern is one of scattered
low clouds in the morning increasing to broken clouds or overcast by
afternoon. By mid-afternoon it is very common to have towering cumulus
or cumulonimbus clouds extending above 50,000 feet. After a nocturnal
thunderstorm, clouds frequently dissipate by midmorning.
Ceilings are low at this time of year and air-to-ground visibility
is generally poor. During the early morning the ground frequently is
obscured by fog. Scattered clouds begin to build up later in the morning
and, although in many cases they do not constitute a normal ceiling of
60 percent or more of cloud cover, they are low. They restrict visibility
and make flying difficult. Shower or thunderstorm activity later in the
* Region A Laos and the Highlands of Northwest North Vietnam), Region
B (Northern North Vietnam), and Region C (Southern North Vietnam) are
shown on the accompanying map.
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day would reduce the ceiling and make low-level flying very hazardous.
Probably the best time of day for flying is between 0800 and 1000, after
the fog has cleared and before shower activity has begun.
Turbulence associated with the towering cumulus and cumulonimbus
cloud formations is widespread and can be very severe in thunderstorms.
Minimum turbulence occurs at night after 2200 and before daylight --
except during nocturnal thunderstorms, which are more serious than those
during the day because they are more difficult to see from the air.
2. Autumn Transition Season (Mid-September to Mid-October)
During this season, cloudiness decreases as the drier, cooler
air from the northeast monsoon begins to enter Laos. There is.a marked
decrease in the total amount of low-lying clouds and a corresponding
increase in the frequency of clear days. Thunderstorm activity still
occurs but not as often. Clouds continue to build up toward afternoon,
except along the Mekong River where low clouds that have accumulated
during the night tend to dissipate during the day. Air-to-ground vis-
ibility is markedly better than in the southwest monsoon season. Morning
fog is still very common, but clearer skies and higher ceilings provide
much better visibility. It is possible that the mountainous terrain
would provide enough identifying features above the fog for navigation
checkpoints and that some missions could be carried out despite the
restricted ground visibility. The best time of day for air operations
is from 0800 to 1000, before the general cloud buildup of midafternoon.
From 1700 until dark is generally another period of good air-to-ground
visibility.
3. Northeast Monsoon Season (Mid-October to Mid-March)
The northeast monsoon season is the best time of year for
air operations. Skies are frequently clear and cloudiness is at its
seasonal minimum, although there are considerable variations locally,
especially in the south where moist air enters Laos through low passes
in the Chaine Annamitique and the resultant cloudiness is somewhat heavier
than in the rest of the country. Morning fog still occurs, especially in
the deeply entrenched northern valleys where it is often so thick that as
it lifts, layers of low clouds form. An afternoon buildup of cumulus
clouds is common, but complete overcast even at this time of day is rare.
Weather conditions are generally good, and air-to-ground visibility is
at its best. Near the end of this season the smoke from brush fires
sometimes interferes with air-to-ground visibility.
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Ii. Spring Transition Season (Mid-March to Mid-May)
Cloudiness increases gradually, and visibility becomes poorer
as the spring season progresses. At times, cloud amounts increase rather
abruptly, especially in association with thunderstorm activity. Thunder-
storms are most violent at this time of year, and severe turbulence
associated with them as well as widespread convective activity is common
throughout the country. In late April and early May, the steadily increas-
ing daily amounts of cloudiness are reflected by increased frequencies of
low ceilings. Also early in the season, when it is relatively dry,
air-to-ground visibility is hampered by smoke from brush and grass fires.
The smoke and dust are generally dispersed as thunderstorm activity
increases, wetting down the ground and clearing the atmosphere, but by
this time cloudiness is building up to its summer seasonal peak. In
general, conditions for flying are not as bad as during the summer
southwest monsoon but are much poorer than during the winter northeast
monsoon.
B. Regions B and C -- Northern and Southern North Vietnam
1. Southwest Monsoon Season (Mid-May to Mid-September)
The wet southwest monsoon brings much cloudiness to North
Vietnam, and conditions for air operations during this season are poor
in the north and only fair in the south. Cloudiness is most widespread
in the north, where the mechanical uplifting of the air as it reaches
the mountains combines with the normal convective processes to form large
cumulus or cumulonimbus clouds. On the leeward side of the Chaine
Annamitique south of Thanh Hoa the atmosphere becomes somewhat drier
because of the downslope motion of the airstream after it has crossed
the mountain barrier, and cloudiness is somewhat less than in the north.
Air-to-ground visibility is not good during this season even though
clouds are usually scattered. Fleecy clouds at low elevations commonly
interfere with effective visibility for pilots. During the morning,
cloud bases below 1,000 feet are common, but, as the day continues, low
clouds tend to disappear and the cumulus cloud bases usually form at
elevations of 2,000 to 3,000 feet. During the frequent midday thunder-
storms, which are usually short, ceilings are considerably lower. Com-
pletely clear afternoons over any part of North Vietnam are relatively
rare during the southwest monsoon season. In general, the best time of
day for an air operation during this season is from 0900 to 1100, at which
time the morning fog has burned off and the midday buildup of clouds has
not yet reached its peak. Conditions in the south are slightly better
than in the north. Even at its worst in mid-afternoon, air-to-ground
visibility is still frequently good in the south and definitely better
than in the north. Visibility at night is generally good after midnight.
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Extensive low stratus clouds occur whenever a typhoon enters the
Gulf of Tonkin and approaches within 100 miles of the coastline, and
they reduce visibility considerably. During this season typhoons are
most common from late July on, and the passage of a typhoon over the
country would disrupt all air operations for a few days.
2. Autumn Transition Season (Mid-September to Mid-October)
In autumn, conditions for air operations begin to improve
in the north and deteriorate in the south. This is probably the best
time of year for air operations in the northern part of the country, as
there is a marked decrease in amounts of cloud cover. Conditions are
poor in the southern part of the country, which is on the windward side
of the Chaine Annamitique at this season and receives increasing amounts
of precipitation with accompanying heavy clouds. In the north, low
ceilings are slightly less frequent and air-to-ground visibilities are
slightly better in autumn than during the preceding southwest monsoon
season, mainly because there is less thunderstorm activity. In contrast,
the conditions for air operations in the south have deteriorated from
those of the southwest monsoon season. Afternoon convective activity
combined with the orographic effects of the rising moist airmass from
over the Gulf of Tonkin causes frequent showers, and as a result visi-
bility is reduced. As in the southwest monsoon season, the best time of
day for air operations probably is 0900 to 1100, but conditions are better
in the north than in the south. In the north the period from about 1700
until darkness also offers good conditions for flying. This is the
typhoon season and one of these storms may strike North Vietnam at any
time, totally disrupting operations for a few days.
3. Northeast Monsoon Season (Mid-October to Mid-March)
Although weather conditions become generally good in Laos
during the northeast monsoon season, conditions for air operations in
southern North Vietnam are poor. This is the cloudiest time of the year,
as the frequency of cloud bases at low altitudes increases. Conditions
in northern North Vietnam remain fair with generally favorable flying
conditions until the advent of the crachin in January.
The pattern of favorable conditions in the north and unfavorable
conditions in the south changes about December to general unfavorability
everywhere as the crachin approaches. This period of low persistent
overcast with fog and drizzle and, few, if any, sunny days lasts through
the remainder of the northeast monsoon season and into the spring. During
the crachin, which is most widespread from January until early April, the
persistent low clouds, drizzle, and poor air-to-ground visibilities
frequently make air operations that depend on visual contact with the
ground impossible. Skies are generally clear above 6,000 to 8,000 feet,
but the land is obscured. In general, the crachin is a coastal condition
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and is restricted to the eastern lowland areas, although it does move up
some of the gently sloping valleys and penetrates adjacent upland mountain
areas. Breaks of clear weather during the crachin season are infrequent.
In the southern part of North Vietnam the crachin is not as widespread or
as well developed as in the north, and the chances of good weather for
air operations are slightly better.
4. Spring Transition Season (Mid-March to Mid-May)
During the early part of this season the crachin is still in
evidence, but the forces that create and maintain it are rapidly weakening.
Spring is a season of decreasing cloudiness and increasing thunderstorm
activity. Conditions for air operations are generally favorable, at least
in comparison with the preceding and succeeding seasons. They are much
better than during the latter part of the northeast monsoon and at least
as good as during the southwest monsoon of summer. Conditions in the
south probably are at their best for the year. The best time of day for
air operations probably is late morning, after the morning clouds have
been burned off by the sun, which is almost directly overhead at this
time of year. Thunderstorms are particularly violent at this season,
and turbulence associated with them is severe.
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Laos and North Vietnam
Generalized Seasonal Evaluation of Weather Conditions for Air Operations
Southwest Monsoon
(Mid May to Mid-Sep)
Autumn Transition
(Mid-Sep to Mid-Oct)
Northeast Monsoon
(Mid-Oct to Mid Mar)
Spring Transition
(Mid-Mar to Mid May)
Region A
Laos and Highlands Region B Region C
of Northwest North Vietnam Northern North Vietnam Southern North Vietnam
Fair
Fair Fair a/
Good 1
Fair
(Mid-Oct to Dec)
Poor
(Dec to Mid Mar)
Fair to Poor Fair to Poor
a. Best season for air operations.
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Fair 1
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Table 2
Xeos an:. _oort1i Vie t:ai,:
can ~10uciness
Station
man
Feb
':ar
'
Hanoi
77
84
87
82
Ldo Kay
85
83
77
71
`ion Cay
77
87
87
83
Nam Dinh
82
86
go
31
Dong Hoi
78
78
77
Vinh
34
87
84
74"
Luang Pracang 53
34
32
36
Pakse
40
39
45
60
Thakhek
19
32
37
.,entiane
3!
39
35
a
J n
Jul
"a
Ser.
Oct O
Nov
c
75
78
78
77
68
6o
67
68
68
73
74
71
68
73
76
75
75
7;
76
74
65
56
60
65
73
71,'
79
70
73
61
66
68
-
66
73
a,
71
73
73
74
77
76
33
83
51
59
69
69
54
47
50
52
73
32
38
36
36
68
61
48
71
31
31~
14
76
48
33
25
48
73
3_
98
34
73
51
39
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North Vietnam
Mean and Maximum Number of Days with Crachin Weather
Feb
Mar
Apr
May
Jun
Jul
Aug
SL
Oct
Nov
Dec
Hanoi
Mean
11
12
19
13
1
_/
0
a/
0
1
3
8
Max
18
20
23
20
3
1
0
0
3
9
17
Mon Cay
Mean
11
12
16
12
a
0
0
0
0
1
5
8
Max
16
18
25
19
1
0
0
0
0
2
13
21
Nam Dinh
Mean
10
13
19
12
1
0
0
0
a
1
5
8
Max
15
18
27
18
3
0
0
0
2
3
10
16
Dong Hoi
Mean
9
9
10
4
0
0
0
0
0
1
7
8
Max
17
18
16
9
0
0
0
0
0
1
14
17
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Generalized Seasonal Evaluation
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of Weather Conditions, by Region
7
Phan Thiet
-~ AIGON
SEASON A B C
SW MONSOON Poor Poor Fair
on MYT o
AUTUMN Fair Fair* Poor
Xuyen ) Vung Tau
NE MONSOON Good* (to Dec) Poor
i
Sa c
Fa
r
(after Dec)
Poor
DAD HU QUOC Can
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Loi
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0 50 100 150Kilometers
CON SON
I P 0
NAMES AND BOUNDARY REPRESENTATION
ARE NOT NECESSARILY AUTHORITATIVE
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20 April 1966
Distribution List for CIA/BI GM 66-3, Effects of Weather on
Tactical Air Operations Over North Vietnam and Laos Only
(Destroy this List after Distribution is made)
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Room 4D825 Pentagon
1 - Edward Van Sant
Office of Foreign Economic Affairs
Department of Defense
Director of Defense Research and
Engineering
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Department of State
Director of Intelligence and Research
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Department of State
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National Indications Center
Room 1E821 Pentagon
NSA (via GB-31 Hqrs.) STATINTL
National Security Council
Information Liaison
Room 369 Executive Office Building
National War College
Fort Lesley J. McNair
Classified Recrods Section
USIA, IRS/A, Room 1002,
1750 Pennsylvania Avenue, N.W.
Attn: Warren Phelps
DIASA-2C, Room 2D233 Pentagon
Attn: Chief Jonas
DIAXX, Room 1+A1088 Pentagon
Lt. Gen. A. J. Goodpaster, Jr.
Assistant to the Chairman
Joint Chiefs of Staff
Department of Defense
Room 2E873 Pentagon
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
INTERNAL DISTRIBUTION
No. of Copies
Recipient
DDI/CGS/HR/Ops, Room 1-G-81 Hqs.
DDI/CGS/SIGINT/Guide, Room 6-G-28 Hqs.
D/OBI, Room 1002, Magazine Building
OCR/BR, Room 1-H-61+ Hqs.
OCR/DD/AB/IPI, Room GE-47 Hqs.
OCR/GR, Room 1-E-1+810 Hqs.
FIB/SR/CR, Room 1-G-27 Hqs.
OCR/LY/DOC, Room 1-H-1107 Hcjs.
D/OCI, Room 7-G-15 Hqs.
DONE, Room 7-E-1+7 Hqs.
Oper. Center, Room 7-F-33 Hqs.
DCS/SD, Room 811 Key Building
OCR/FDD, Room 1+15 Key Building
D/OSI, Room 6-F-1+0 Hqs. STATINTL
NPIC/CSD/REF, Room 1S518,
1-B-1+021+ Hqs.
DDI/CGS/HR/T, Room 3-E-56 Hqs.
DDS&T/OSA, Room 6-B-1+0 Hqs.
OS/SRD/CAB, Room GE-31 Hqs.
OTR/IS/IP, Room 532, 1000 Glebe
VMR, A-18
ORR, Room GH-0915 Hqs.
OCR/DD/Standard Distribution
COS, Saigon
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 Approved For Release 2001J08/14~ CIA-RDP84-00825R000100090001-6
Distribution List for CIA/BI GM 66-3, Effects of Weather on
Tactical Air Operations Over North Vietnam and Laos Only
(Destroy this List after Distribution is made)
EXTERNAL DISTRIBUTION
No. of Copies
17
Recipient
Defense Intelligence Agency
DIASQ-3 Building A.
Arlington Hall Station
Assistant Secretary of Defense, ISA
Room 1tD825 Pentagon
1 - Edward Van Sant
Office of Foreign Economic Affairs
Department of Defense, 3a~ two=
Director of Defense Research and Engineering
Room 3D139 Pentagon
Department of State
Director of Intelligence and Research
Room 6531. State Department Building
Department of State
INR Communications Center
Room 6527, State Department Building
National Indications Center
Room 1E821. Pentagon
NSA - (via GB31 Hqrs.) STATINTL
National Security Council
Information Liaison
Room 369 Executive Office Building
National War College
Ft. Lesley J. McNair, Classfied Records Section
USIA, IRS/A, Room 1002, 1750 Pe msylvania Ave.,NW
Attn: Warren Phelps
DIASA-2C, Room 2D233
Pentagon
Attn: Chief Jonas
DIAXX, Room )4A1088, Pentagon
Lt. Gen. A. J. Goodpaster, Jr.
Assistant to the Chairman
Joint Chiefs of Staff
Department of Defense
Room 2E873, Pentagon
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 Approved For Release 2001/08/14: CIA?RDP84-00825R000100b9000'I-6
k
D .st ribt ion
ist f?r CIA/$I GM. 66-3,
E'fectpo
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 Approved For Release 2061/08/14: CIA-RDP84-00825R000100090001-6
INTERNAL DISTRIBUTION
Recipient
DDI/CGS/SIR/Ops, Room 1G81 Hgrs.
DDI/CGS/SIGINT/Guide, Room 6G28
D/OBI, 1002 Magazine Building
OCR/BR, Room 1H64 Hqrs.
OC R/DD/AB/IPI, Room GE47. Hq~s.
OCR/GR, Room lE4810 Hors.
FIB/SR/CR, Room 1G27 Hqrs.
OCR/LY/DOC, Room 1H1107 Hqrs.
0/OCI, Room 7G15,Hgrs.
D/ONE, Room 7E47 Hgrs.
Oper.Center, Room 7F33 Hqrs.
DCS/SD, 811 Key Building
OCR/FDD, Room 415 Key Building
D/OSI, Room 6F40 Hgrs.
NPIC/CSD/REF, Room 15518,
1B4004 Hqrs.
DDI/CGS/HR/T, Room 3E56 Hqrs.
DDS&T /OSA, Room 6B40 Hqrs.
OS/SRD/CAB, Room GE31, Hqrs
0TR/IS/IP, Room 532, 1000 Glebe
VMR, A-18
Office of Research and Reports,
OCR/DD/Standard Distribution
Room GH 0907 Hqrs.
350
Hqr,
2 Director
1 CD/BI
2 ED/BI
5 GD/BI
2 NLD/BI
2 PD BI
Room GH0915 Hqrs.
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
Standard Form 63
Novombor 1961
GSA FPMR (41 CFR) 101-11.6
MEMORANDUM OF CALL
^ RETURNING YOUR CALL
0 IS REFERRED TO YOU By:
'LEASE CALL
LEFT THIS MESSAGE:
U.B. GOVERNMENT FAINTING OFFICE ; IYI5 OF-755_153_Ip=-
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 ,Approved For Release 2001/08/14 :
9,10
"Approved For Release,2, 001/08/14: CIA_RDP84-00825R000100090001-6
THE SITUATION IN SOUTH VIETNAM
SECRET
WEEKLY
Recipient
Special Asst. to the President for
National Security Affairs
The White House
The Vice President
The White House
Lt..Col. Richard Bowman
Military Asst. to Special Asst. to the
President for National Security Affairs
Via: Information and Liaison Staff, NSC
Room 365, 3;xecuti.ve Office Bldg.
Deleted ]4 April 1966
St(~3ex,~r~~X~c
The Hon. Dean S. Rusk-
Secretary"of State
Mr. Averell Harriman
Ambassador -at -Large
Department of State
Ambassador Leonard Unger
Special Asst. for Vietnamese Affairs
Department of State
Mr. Thomas L. Hughes
Director, Intelligence-and Research
Department of State
Mr. William P. Bundy
Asst. Secretary for Far Eastern Affairs
Department of State
Mr. Samuel D. Berger
Deputy Asst. Secretary for Far Eastern
Affairs
Department of State
 Approved For Release 2001/0,8/14:4-00825R000100090001-6
i o For F2eleas '.200-1108/14.; GJA-RDP84.0082 9060.100090001-6
Mr. William C. Trueheart
Director, office of'Southeast Asian
Affairs
Bureau of Far Eastern Affairs.
Department of State
Mr. David C. Cuthell
Director, Office of Southwest Pacific
Affairs
Bureau of Far Eastern Affairs
Department of State
Mr. Robert W. Barnett
Deputy Asst. Secretary for. Far Eastern
Economic Affairs
Bureau of Far Eastern Affairs
Department of State
Miss Ruth Bacon
Office of Regional Affairs
Bureau of Far Eastern Affairs
Department of State
Mr. Robert A. Fearey
Director, Office of East Asian Affairs
Bureau of Far Eastern Affairs
Department of State
Mr. Harold U. Jacobson
Director, Office of Asian Communist
.
,
Affairs
Bureau of Far Eastern Affairs
Department of State
Mr. Richard L. Steider
Public Affairs Adviser
Bureau of Far Eastern Affairs
(Department of State
Mr. Robert H. Miller
Director, Vietnam Working Group
Bureau of Far Eastern Affairs
Department of State
'Mr. Henry B. Cushing
Assistant to Deputy Director for
Lepartment of State
 Approved For Release 2001/0.8/1A:ZJA-:I P84-00825R000100090001-6
Mr. Jeffrey C. Kitchen
Deputy Assistant Secretary
Politico-Military Affairs
Deputy Under Secretary for Political
Affairs
Department of State
Mr. George A. Furness, Jr.
Office of Research and Analysis for
Far East
Bureau of Intelligence and Research
Room 7421
Department of State.
Mr. Donald Q. Coster
O/FSI/IS
Room 109
State Annex - 3/W
Mr. Walt W. Rostov
Counselor of the Department and
Chairman of the Policy. Planning Council
Room 7261
Department of State
Mr. Robert H. Johnson
Policy Planning Council
Room 7517 A
Department of State
Mr. Joseph J. Fisco
Assistant Secretary
.Bureau of International Organizations.
Affairs
Room 6323
Department of State
Mr. Bruce M. Lancaster
Director, Operations Center
Room 7516, Department of State
Mr. Llewellyn E. Thompson
Ambassador-at -Large
Room 7207
Department of State
Mr. John E. Merriam
Secretariat Staff, Executive Secretariat
Room 5239 C
Department of State
-.Approved. For Release 20b1/0& 'P4- CIA-RDP84-00825R000.100090O01-6
 Deputy-Asst. Secretary of'State
Public Affairs
Room 6804 A
Department of State"
'Mr. Mr . Paul M. ICatte nbur
'Office of Southwest Pacific Affairs
Bureau of Far Eastern Affairs
Department of State
Mr. George Aldrich
Asst. Legal Adviser`
Far Eastern Affairs,
Room 6420
Department of State
Mr. David E. Bell
Director, Agency for
Development
Mr. Walter Stoneman
Deputy Assistant Administrator
East
AID
Room 6212, Department of State
Mr. William S. Mazzocco
Director, Office of. Vietnam Affairs.'
AID
Room 3317, Department of State
Mr. Curtis Farrar
Director, Office of Southeast Asian
Affairs
AID, Room 5212
Department of State
The Hon. Robert S. McNamara
Secretary of Defense
The Ron. Cyrus R. Vance
Deputy Secretary of Defense
The Hon. John T. McNaughton
Assistant Secretary of Defense
(International Security Affairs)
Office of Secretary of Defense
orRelea~~e\2001108/14 CIA-RDP84-008 5 OQ h0009
rS..-..~ Sd~n ~
Approved For? Release 2001/08/14: O4A RD 00825R000100090001-6
 Approved For Release 2001/08/14 : t1ARDP84-00825R000100090001-6
Mr.-Peter Solbert
Deputy Assistant Secretary
(International Security Affairs)
Office of Secretary of Defense
The Hon. Alain Enthoven
Assistant Secretary of Defense for
Systems Analysis
Office of Secretary of Defense
Rear Adm. Francis J. Blouin
Far East Region
Director
,
(International Security Affairs)
Office of Secretary of Defense
Capt. V. G. Hoizappel, USN
Acting Chief, Coordinating Division
Policy Planning Staff.
(International Security Affairs)
Office of Secretary of Defense
OSD Cable
Office of Secretary of Defense
Lt. Gen. Joseph F. Carroll
Director, Defense Intelligence Agency
Via: DIASA-2C, Room 2 D 233,.Pentagon
Maj. Gen. Robert Taylor
Defense Intelligence Agency
Via: DIASA-2C, Room 2 D 233, Pentagon. PROM
DIAAP-2C, Room
Via.: DIASA-2C, Room 2 D 233, Pentagon
Chief, Yankee Team Task Force
DIAXX-3, Room I D 918
Via: DIASA-2C, Room 2 D 233, Pentagon.
Major Gen. John J. Davis
Assistant Chief of Staff for.Intel,
ligence
Department of Army
Via: DIASA-2C, Room 2 D 233, Pentagon'
Brig. Gen. Jack E. Thomas
Assistant Chief of Staff, Intelligence
United States Air Force
Via: DIASA-2C, Room.2 D 233, Pentagon .
Approved For Release 2001/08/14"`'ClA-RDP84-00825R00010b090001.-6
A t1l f~ ~~ ~~ ~l
 Approved For Release 2001/08/14t,.ClA RED~P84-00825R000100090001-6
Rear Admiral Rufus L. Taylor''
Assistant Chief of Naval Operations
(Intelligence)
Department of Navy
Via: DIASA-2C, Room 2 D.233,'Pentagon
Colonel It. C. Berkeley
United States Marine Corps
Via: DIASA-2C, Room 2 D 233, Pentagon.
Major Robert Rolf
Intelligence Support Facility, USASSD
Via: DIASA-2C, Room 2 D 233,.Pentagon
Rear Adm. W. F. A. Wendt
Director, Strategic Plans Division
Room 4 E 566
Via: DIASA-2C, Room .2 D 233, Pentagon
Rear Ada. Walter F. Schlech, Jr.
Director, Politico-Military Policy Div.
Room 4 E 572
Via: DIASA-2C, Room 2 D 233, Pentagon
Lt. Gen. V. P. Mock
Deputy Chief of Staff for Military
Operations
Room 3 E 648
Via: DIASA-2C, Room 2 D 233, Pentagon
Eastern Division,
Intelligence Support and Indications
Center
Defense Intelligence Agency
Via: DIASA-2C, Room 2 D 233,'Pentagon
Gen.. Earle G. Wheeler
Chairman
Joint Chiefs of Staff
Maj. Gen.. William R. Peers .
Joint Chiefs of Staff (SA.CSA)
Room I E 962,, Pentagon
Lt. Gen. David.A. Burchinal
Director., Joint Staff
,Joint Chiefs of. Staff
`Ma j;. Gen.. :Ashton -5 .. Manh.Vt
Secretary,, ,Jo.int Chiefs ,of .;Staff
For Release; 2,001/08/1 +??lA-RDP84-00825R000100090001-6
 Approved For Release 2001/08/141A-R.LP84-00825R000100090001-6
Col. John B. Kidd
Chief of Pacific Division,,
Joint Chiefs of Staff
Room 2 B 920, Pentagon
Mr. Dichran Y. Hovsepian
Chief, Geographic Branch
Mapping and Geodesy Division
Office of Chief of Engineers
Room 1336, Bldg. 77, Gravely Point
Via: DIASA-2C, Room 2 D 233, Pentagon
Lt. Gen. Marshall S. Carter
Director, National Security Agency
Fort George G. Meade, Maryland
Via: CIA Liaison Staff
Mr. Howard C. Brown, Jr..
Assistant General Manager
istration
Atomic Energy Commission
Germantown, Maryland
Mr. William C. Sullivan
Assistant to the Director
Federal Bureau of Investigation
Room 1018, 315 9th St.,'N.W.
xrector,
1 E 821, Pentagon
EYES ONLY - PERSONAL
CIA Representative
National Military Command Center
Room 2 D 901A, Pentagon
DCI
DDCI
EXECUTIVE DIRECTOR
Approved'For 'Release.2001'/08/14: CIA-RDP84-Q085}OO0100090001-6
~1
 Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
25)1A
87'62
net ~.tPd 4[8]6.6
'25XiA,
25X1A
25XIA
--llar~ ~i-sr
Western- Hemisphere- -: iv.
25X:1 A.
,25X1A.
.--MH/C-GS
PjDDP-r _ I
I nnm riG..27O8 i grs-..,,:.$J.dgw
5&,._}I&j - Bldg.
6
Approved For Release 2001./08/14: CIA-RDP 4-00825800010009.0001-6
Room. 5 D 3123, Hdgrs.? Bldg.
Room 4 D 14, Hdqrs... Bldg.
Room 4 D 01119 Hdqrs. Bldg.
 Approved For Release 2001/08/14 A:FibP84-00825R000100090001-6
25X1A.
Rv?m y, mat . : B~:dg.
119--121 Special Asst-for Vietnamese Affairs
Eff. 4/5/66
25X1A
COMUS MACV
Via: DIASA-2C ATTN:
oom 2 D 233, Pentagon
Colonel Patterson
25X1A
CINCPAC J-2
Via: DIASA-2C ATTN:
Room 2 D 233, Pen agon
11
Ambassador Elbridge Durbrow
Air War College
Maxwell Air Force Base, Alabama
Via: INR Communications Center
Room 6527, Dept. of State
Approved For Release 2001/08/L4)_CIA-RDP84-00825R000100090001-6
25X1A
 Mr. Melvin L. Manfull
American Embassy, Saigon
Via: INR Communications.Center
ATTN: Mr. S. Solomonson
Room 6527, Department of State
(DO/II will forward)
Mr. Robert H. Miller Eff. 25 March 1961
Director, Vietnam Working Group
Bureau of Far Eastern Affairs
Department of State
Mr. Robert T. Burke 3/29/66
State Department Advisor
Ft. Bragg, North Carolina
VIA: INR Communioatfbpus Center
Room 6527
Department of State
Mr. Robert K. German 4/13/66
Bureau of Intelligence and Research:.:.
Office of Research and Analysis for
Soviet Bloc
Room 7422, Department of. State
AUL (AUL3T-66-D3)
Maxwell AFB, Ala. 36112
VIA: DIASA-2C
ATTN:
Approved For Release 200110a144: CIA-RDP84-00825R000100090001-6,
Approved For Release 2001/0$/'1T:"d RDP84-00825R000100090001-6.
 Approved Felease 2001/08/14: CIA-RDP84-008000100090001-6
DISTRIBUTION LIST
TITLE OF REPORT
DATE
REPORT NO.
/ _ '31
PROJECT NO.
1
CLASSIFICATION
CONTROL
NAME OF REQUESTER
NAME OF ANAL
YST
BRANCH
GRAPHICS
RECIPIENT
DATE SENT
4
,r.
IF
STATINTL
STATINTL
B
S -t-
~~ L.7
STATINTL
6E R
19
~-`- 7
FORM
12.64 2362
 Approved For~Release 2001/08/1tCgcp84-00828 00100090001-6
Effect of Weather on Air Opr. in Laos and North Vietnam pN 61.2286
Revi6es GB 65-17)
DD/I
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
&M:66-3
 Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
GM 66-3
GM 66-3 is not to be disseminated.,
on order from DD/I and D/OBI.
For earlier study, see GB 65-17?
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 Approved F Release 2001/08/14: CIA-RDP84-008 58000100090001-6
NOW,
GM 66-3
20 April 196b Report ready for dissemination. 10 copies picked up from PSB.
Brammell said to hold.
Apparently DD/I wants to know changes made that
make this report different from the earlier one:
Changes in one paragraph, 1 additional footnote;
the foreword, and the summary -- GRW says.
22 April 1966 Report to be held and not disseminated, so says
Bramwell. All copies (except above 10 mentioned)
to be sent here by PSD.
Approved For Release 2001/08/14: CIA-RDP84-00825R000100090001-6
 12Apr66
]J Apr66
~s'GL
22Apr66
PROJECT PROPOSAL Written; re rc
is eaovrFc(ru~~le eBO~(~ : CIA-
typing today. STATINTL
Bramwell told that Smith
does not wan is released (report
not materially changed from the
former one); all copies to be sent
here.
:DP84-00825R00 00 90001-6
/3 '7)
Approved For Release 2001/08/14: CIA.
61.22_$6 _Effcot of Weather/Air Opr.,Laos,No.Vietnaii DD/I
 ?roVect N70.
Fe a e t r
61,
DeadlAna 'or Deliv ry to.
the Requester -/-"
ra ch Cie
~,,
3pse1al -A-sat, p,.~- r-
Division ief R ?' r-
Ldi tLn Rev ,ew
Editor
Approved For Rek5- ": k
k aly,3t
S~ Q!
4-8 2 '90100090001-6
E3itor/yat
Typist (final)
Proofreaders
-nralyst
For Ditto
03s Bond with
Other
Viler lnatruc: ti Gns cad Cr taai; is
+,rC33?p' 3~R? g.C::, Sran 't
Final Editorial Approval
Before Reprod wtl oa and
Distribution
ADMMS t S w lh .L ti OI
Le+si,oatfcs4