ARMY SECURITY AGENCY
MISSION AND SACRIFICE
ORIGINS OF THE ARMY SECURITY AGENCY AND
The U.S. Army has supported its fighting forces with signals
intelligence since World War I. The first permanent organization to do
this was established in1930 as the Signal Intelligence Service. During
world War II, the SIS (renamed the Signal Security Service in 1943 and
later the Signal Security Agency—SSA) exploited the communications of both
Germany and Japan, shortening the war and saving many thousands of Americans
The SSA was reorganized as the Army Security Agency (ASA) at
Arlington Hall Station, Virginia, on 15 September 1945. Operating under
the command of the Director of Military Intelligence, the new agency had a
sweeping charter. It exercised control functions through a vertical
command structure, ASA established a worldwide chain of fixed sites—"field
stations"- while maintaining large theater headquarters in the Far East
and in Europe.
In 1949, all three military cryptologic services were centralized
under the new Armed Forces Security Agency (AFSA), the precursor of today’s
National Security Agency. ASA transferred most members of its large
civilian headquarters staff to AFSA in this process. However, because of
the need once again to support troops in actual combat in the Korean War, ASA
again expanded, deploying tactical units on a large scale to support the Army
in combat. For the first time, ASA grew to include groups and battalions
in its force structure.
In 1955, ASA took over electronic intelligence (ELINT) and
electronic warfare functions previously carried out by the Signal Corps.
Since its mission was no longer exclusively identified with intelligence and
security, ASA was withdrawn from G-2 control and resubordinated to the
Army Chief of Staff as a field operating agency.
In the 1960’s, ASA was again called upon to assist US forces in the
field. On 13 May 1961, the first contingent of Army Security Agency
personnel arrived in south Vietnam (setting up as organization at Tan Son Nhut
Air Base) to provide support to the U.S. Military Assistance Advisory Group and
help train the South Vietnamese Army. During the early years of conflict,
ASA troops in Vietnam were assigned to the 3rd Radio Research Unit. Their
primary mission was to locate Viet Cong transmitters operating in the
south. This mission was in its early stages when one of their direction
finding (DF) operators, SP4 James t. Davis, was killed in a Viet Cong ambush on
a road outside of Saigon. The date of the ambush, 22 December 1961, made
Davis the first American soldier to lose his life during the Vietnam War.
The death of Davis brought home to the ASA the dangers of proceeding into
the jungle with short-range equipment to locate VC transmitters that might be
only a few miles away. Since radio wave propagation in Southeast Asia
required that DF equipment be very close to the transmitter, the obvious answer
was to go airborne. ASA engineers began working on the problem, and by
March 1962 they had their first airborne DF platform, a single engine aircraft
that flew low, slow and had room for only a few people.
In the fall of 1962, one veteran arrived in Vietnam assigned to the
3rd Radio Research Unit. He recalls that after Davis was killed operating
a jeep-based PRC-10 direction finding unit, someone decided that this function
could be better handled from the air. Within days, soldiers in the unit
were calling it TWA (Teeny Weeny Airlines).
With the introduction of large U.S. ground combat elements into the South
Vietnam in 1965, the ASA organization in-country expanded. The 3rd RRU
was replaced by the 509th Radio Research Group, which commanded three
battalions and company-size direct support units assigned to tall Army
divisions. One of the 509th’s subordinate battalions was the 224th
Aviation Battalion (Radio Research), which pioneered in the introduction of
Special Electronic Mission Aircraft (SEMA) to the battlefield. At the
height of the war, the 509th Radio Research Group commanded some 6,000 ASA
personnel in-country. Meanwhile, the agency itself had greatly expanded,
reaching a strength of 30,000 and attaining the status of a major Army field
command in 1964.
However, the massive drawdown of the Army after the Vietnam War led to pressures to achieve economics by the consolidation of intelligence functions. In 1975, the Army Chief of Staff accepted the recommendations of the Intelligence Organization and Stationing Study and agreed to a wholesale reorganization of Army intelligence. The3 decision was made to create multidisciplinary military intelligence organizations within the Army at both the tactical and departmental levels. As a result, ASA was effectively dismembered. ASA’s tactical units were resubordinated to the local commander, its functional responsibilities for training and research and development spun off to other major army commands (MACOMS), and its headquarters and fixed sites used as the nucleus of a new intelligence and security MACOM. On 1 January 1977, Headquarters, U.S. Army Security Agency, was redesignated as Headquarters, U.S. Army Intelligence and Security Command.
AIRCRAFT USED FOR
SPECIAL ELECTRONIC MISSION AIRCRAFT (SEMA) IN VIETNAM
Following World War II, little was done in the Army’s airborne
signal intelligence arena. Through the 1950’s ASA operators flew
electronic reconnaissance missions in the Navy EA-3B Sky Warriors. In the
early 1960’s ASA crews again flew on board the EA-3B’s within a project called
FARM TEAM. It was at this point that the Army had made a decision to
invest manpower and funds in order to have its own ability to expand its
intelligence coverage of enemy forces within a theater of operations which
appeared to be increasing in both size and complexity.
The early days of Vietnam truly marked the beginnings of the Army
airborne signals intelligence. The Army’s U-6 Beaver was one of the first
platforms converted from a utility mission to take on intelligence collection
efforts from the air. As a result, it was officially redesignated as the
RU-6. This, in effect, initiated the process wherein most of the remaining
Army aircraft which eventually became incorporated within the emerging fleet of
signals intelligence platforms, were also redesignated with a reconnaissance or
"R" prefix designator.
The RU-6 aircraft was a relatively simple and basic platform equipped
with on-board mission receiver equipment for homing in on signals emitted from
enemy forces. The data returned were only as accurate as the pilots’
navigational skills. With no Doppler/inertial navigation system (INS) or
global positioning system, the pilots relied on landmarks and dead reckoning to
determine their known location from which to calculate the intercepts.
One veteran recalls his early days in Vietnam flying in a Caribou with
experimental system. The operators hung a long wire out the back of the
aircraft for a crude direction finding antenna. Crews in hot, humid
conditions in very loud aircraft. Missions were often four hours long,
but could be longer depending on the operational tempo of the forces in
contact. It has been said that air missions produced as much as one third
of the intelligence known to ground forces.
The single-engine companion Army platform, the RU-1 Otter, was similarly
configured with personnel and equipment, but it was an expanded platform.
However, it wasn’t until the introduction of the Army’s RU-8D Seminole that a
significant advance was made in the SEMA fleet and in the contribution these
intelligence platforms were providing the theater tactical commanders. In
addition to having on-board mission equipment similar that found initially on
both the RU-6 and the RU-1A, the RU-8D aircraft were equipped with the Marconi
Doppler navigation system. This required the copilot to manually plot the
ARDF fixes (locations) on large pads of scale graph paper on his lap.
(Masking tape was applied to the aircraft doors to prevent the plotting sheets
from beings sucked out of the aircraft.) Also, The RU-8Ds were equipped
with blade antennas on the wings, which gave them the capability to home in on
a transmitter and fly a standard flight pattern to achieve the geometry
necessary to obtain several lines of bearing (LOB’s) and to create a fix of the
Although overflight of the actual target sometimes occurred, the
procedure for flying the pattern for triangulating the target tried to prevent
overflight whenever possible. Additionally, some of the aircraft were
configured with radio fingerprinting to further enhance signal
identification. The mission gear on board these RU-8d aircraft were known
by the nicknames WINEBOTTLE, CEFISH PERSON, and CHECKMATE. These
aircraft, with the on-board systems and crews, truly became the new workhorse
of the Army’s SEMA fleet primarily due to a combination of the improved
capability, each contributing to expanding and improving the unit’s mission
coverage in several dimensions.
In 1968, a project known as LAFFIN EAGLE entered service with the
Army and with in Vietnam. It used the Army RU-21 aircraft with
additionally improved mission gear to include an automated direction finding
capability as a result of the use of an on-board inertial navigation system.
With the follow-on introduction of three JU-21 LEFT JAB into
Vietnam, the Army now had the first airborne collection system to give 360-degree
direction finding coverage. It was also the first system to use a digital
computer to store the calibration tables for the DF system and to calculate
emitter locations from the LOBs generated by the "Spaced Loop" DF
antenna and aircraft position data furnished by the on-board INS. In
essence, what the RU-6a, the RU-1A, and, most importantly, the RU-8D had
provided and accomplished as the Army’s initial trio of signals intelligence
platforms was now resident in the proliferating fleet of RU-21s in both Vietnam
Finally, a truly special unit was formed and deployed to Vietnam
using Army pilots, Army ASA mission operators on board a Navy P-2V Neptune
four-engine aircraft. This Army project was a significant leap in both
mission coverage and overall mission capability. As with most of the
other platforms, these aircraft were redesignated specifically as RP-2E
aircraft with an associated mission project name of CEFLIN LION or CRAZY CAT.
The remaining platforms which also contributed to the Army’s
airborne signal intelligence were six specially configured UH-1
helicopters. These aircraft were redesignated as EH-1 LEFT BANK aircraft
and were assigned to directly to the tactical war-fighting divisions in
Vietnam. These LEFT BANK assets were manned and maintained by ASA
operators, also found with the same divisions. Their flight profiles
included both high and low extremely low altitude operating enveloped necessary
to locate and target tactically oriented enemy threats of immediate and
Often, the ultimate customers for the information did not understand the
capabilities of the systems. They expected to be able to go to a given
location and find the enemy at that location speaking on the radio. There
were some constraints with the systems, in that the location of the target
could be depicted as an elliptical core - not a pinpoint target.
Therefore, the emitter was not always exactly where the report indicated.
RADIO RESEARCH UNITS IN VIETNAM
Radio Research units (RRU) operated in Vietnam under the direction of the U.S. Army Security Agency (ASA) Group. During this time, these operations were classified and operated under the auspices of the 3rd RRU, activated on 23 May 1961. Its ASA nomenclature was the 400th USASA Operations Unit (provisional) until 23 September 1961 when it was redesignated the 82nd USASA Special Operations unit. The 3rd RRU assets included detachments specifically incorporated the RU-6a, RU-1A, and the RU-8D platforms, mission gear, and crews. On 1 November 1964, the unit was redesignated as the 53rd USASA Special Operations Command and on 1 June 1966 was again redesignated as the 509th USASA Group and as the 509th Radio Research Group (RRG).
On 1 June 1966, the 224th Aviation Battalion (Radio Research) was activated under the command of the 509th RRG. It consisted of four companies:
· the 138th Aviation Company (RR) at Da Nang in support of I Corps
tactical zone of operation
· the 144th Aviation Company (RR) at Nha Trang in support of II Corps tactical zone of operation
· the 146th Aviation Company (RR) at Saigon in support of III Corps tactical zone of operation
· the 156th Aviation Company (RR) at Can Tho in support of IV Corps tactical zone of operation
On 3 July 1967, the 1st Radio Research company (Aviation) was
assigned to the 224th Aviation Battalion (RR) to provide direct support to the
U.S. Military Assistance Command, Vietnam (MACV), flying six RP-2E aircraft
from Cam Ranh Air Base, Vietnam, on 13-hour missions.
By June 1969, the 224th Aviation Battalion (RR) with its
headquarters company and five operational aviation companies had over 1,100
personnel and eighty aircraft. This battalion and the LEFT BANK elements
within the two radio research companies supporting the 1st Cavalry Division and
the 4th Infantry Division comprised the initial fleet of the Army airborne
signals capability in Vietnam.
THE RU-8D AND ITS SIGNIFICANCE TO
The U-8 Seminole was first introduced into the Army’s inventory
during the Korean War. This twin-engine aircraft was used for
transportation of commanders and staff officers.
ASA first used the plane as airborne direction finding platform in
Vietnam. The system became operational in January 1963. The RU-8
offered advantages over the RU-6 Beaver. For the first time the 3rd Radio
Research Unit had an all-weather capability.
Wit it’s ability to carry three crew members (pilot, copilot and
intercept operator), the plane had enough room for navigational
equipment. Unlike the RU-6, a crew would no longer be dependent upon
visual landmarks to conduct operations.
The RU-8 was one of the most flexible and efficient aircraft in the
ASA’s inventory. Because it could operate in mountainous regions, obtain
greater altitude, and offered increased speeds, the RU-8 quickly became the
workhorse in ASA’s airborne direction finding effort in Vietnam. In
Vietnam, there was twice as many RU-8’s as any other platform in ASA’s inventory
and as such they became the backbone of Army airborne direction finding in
Vietnam, Laos, and Thailand. In 1968, forty-four systems were scattered
among three companies: 138th Aviation company (RR), 144th Aviation
company (RR), and the 146th Aviation company (RR).
By 1971, unit drawdowns were beginning. On 30 September 1971 the 144th Aviation Company at Nha Trang was deactivated. More followed with the relocation of the 156th Aviation Company from Can Tho to Fort Bliss, Texas. By 1 May 1972, this left the 224th Aviation Battalion with two companies, the 138th and 146th.
When the word was received from the Commander USMACV in June 1972
that support to Allied forces was still needed, the 224th was in the process of
turning in its remaining RU-8D’s. For the next several weeks the emphasis
was upon retrieving planes from turning in and cannibalizing others for spare
parts. But within ten days the first U-8 was back in the air, and within
three weeks the level of missions had returned to normal.
The RU-8s continued operating until the 28 January 1973 cease-fire
and were among the last platforms to leave Vietnam. Following Vietnam,
the RU-8s would remain as part of the 138th Aviation company (USAR) stationed
in Orlando, Florida.
Three Army crews made the ultimate sacrifice while flying signals
intelligence aerial reconnaissance missions under enemy fire. All three
were lost in the was in southeast Asia and were the only ASA crews killed by
hostile fire during the Cold War.
Thirteen U.S. Army personnel were lost to hostile fire while
performing sensitive airborne intelligence collection missions. Of the
thirteen, seven were U.S. Army Security Agency intercept operators and six were
flight crew personnel. Six of these thirteen are still listed as Killed
In Action/Body Not Recovered. One is listed as Died While Missing/Body
Recovered. The others are listed as Killed In Action.
The first ASA aircraft lost in Vietnam was a LEFT BANK EH-1H
assigned to the 1st Cav Division. The loss took place on 29 November 1969
near Landing Zone Buttons in Phuoc Long Province, III Corps. The mission
of this crew was airborne intercept and location of enemy transmitters directly
threatening the 1st Cav’s area of operations. The aircraft was shot down
by ground fire, and the crew was killed on impact. The aircraft was later
destroyed by tactical airstrikes to prevent compromise of on-board mission
equipment. Those lost were:
CW2 Jack K. Knepp from Big Bear City,
WO1 Dennis D. Bogle from Oklahoma City, OK KIA
SP4 Henry N. Heide II from West Palm Beach, FL KIA
SP4 James R. Smith from Moore, OK KIA
A second LEFT BANK aircraft from the 1st Cav Division was lost on 1
March 1971 near Dambe, Cambodia (approximately five miles inside
Cambodia). Those lost were:
WO1 Paul V. Black from Central Valley,
WO1 Robert D. Uhl from San Mateo, CA KIA/BR
SP5 Gary C. David from Pottstown, PA KIA
SP4 Frank A. Sablan from Phenix City, AL KIA
These mission crews on board the two LEFT BANK aircraft were
assigned to the 371st Radio Research Company. Originally designated as
the 371st ASA Company, it was formed by the United States Army Security Agency
in 1962 and was attached to the 1st Cavalry Division. It was with this
division that the company saw wartime service ion the Republic of Vietnam from
1966 to 1971. The mission of the 371st was to provide combat information
to the division commander in pursuit of his tactical war-fighting
mission. The company served well and faithfully, earning two Presidential
Unit Citations, four Meritorious Unit Commendations, and one Valorous Unit
Award. It was redeployed to Fort Hood with the division in 1971 where it
served with pride until deactivation in 1981. Its lineage and colors are
now perpetuated by Company A, 312th MI Battalion, Fort Hood, Texas.
The last ASA aircraft lost to hostile fire was a U.S. Army JU-21A
LEFT JAB assigned to the 138th Radio Research Company based at Phu Bai, near
the DMZ. On 4 March 1971 it took off on an intelligence-gathering
mission. The aircraft headed northwest towards the DMZ between North and
South Vietnam. Reportedly, the aircraft’s mission was to collect
intelligence regarding surface-to-air missile sites, either in the DMZ or just
north of it. Shortly after departure, the JU-21A, tail #67-18065, was
The crew was declared missing in action. A search effort to
locate the aircraft along its known flight path produced no findings.
Those lost were:
CPT Michael W. Marker from Wichita Falls,
WO1 Harold L. Algaard from Fosston, MN KIA/BNR
SP6 John T. Strawn from Salem, OR KIA/BNR
SP5 Richard J. Hentz from Oshkosh, WI KIA/BNR
SP5 Rodney D. Osborne from Kent, WA KIA/BNR
Retired CW2 Joseph Hayes recalls that day: "I was
scheduled to fly on that aircraft. I had previous morse and DF
experience. That morning, I was just climbing in, when someone came running
up to the plane and told me that I had been bumped. SP6 John T. Strawn
jumped on in my place. My duty assignment as briefing team chief just
took priority over this mission. The CG ASA Pacific, General Wolf was
coming in and a briefing was required. I was put on the next C-130 out of
Phu Bai for Tan Son Nhut. Sp6 Strawn and the rest of the crew took off
shortly thereafter and they never landed."
RECOGNITION IN NATIONAL VIGILANCE PARK
National Vigilance Park stands to honor those "silent
warriors" who risked their lives performing airborne signals intelligence
missions during the Cold War. The RU-8D addition to Vigilance Park,
dedicated on 12 May 1998, represents Army soldiers who were lost while
performing aerial reconnaissance.
The Transportation Museum, Fort Eustis, Virginia, donated the
aircraft, which is completely restored. The symbol on its tail, the
Lonely Ringer, represents the 224th Aviation Battalion. (The wings on the
crest represent Army Aviation and what it stands for. The lightening
bolts portray the strategic striking capability of the battalion.
"Lonely Ringer", the original battalion’s classified mission in
The RU-8D mission equipment is removed from the aircraft and is on
permanent display inside the National Cryptologic Museum. Both of these
exhibits are a fitting tribute to our vigilant servicemen and women who were
lost and to those who continue to serve in this vital mission to our country.
Special thanks to Dennis Buley and Mark Scott of the ASA Veterans Association, James Gilbert, INSCOM historian, for input and review of this brochure, and to COL. (ret.) Carlos Collat and COL (ret.) Richard Mitchell.