Page 6 - Ft. Huachuca Scout 6-5-15

6A The Scout
Military Intelligence – Moment in MI history
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Command Historian, U.S. Army Intelligence
and Security Command
When the Army Security Agency, or ASA, initially
arrived in Vietnam, it fully expected that its direction-
finding, DF, mission would be accomplished via a
network of medium-range ground-based sites and
mobile, low-level DF teams. Unfortunately, Vietnam’s
rugged and heavily vegetated terrain and the enemy’s
low-powered radios combined to frustrate ASA’s DF
efforts.
Since the enemy’s radios did not have the power to
push through the dense vegetation, operators bounced
the radio signals off the ionosphere using steeply
angled sky waves. ASA’s ground-based stations had
difficulty establishing accurate bearings on these sky
waves. In the fall of 1961, Lt. Col. William Cochrane,
commander of the 3rd Radio Research Unit (RRU) in
South Vietnam, asked ASA headquarters to find a so-
lution to the DF problem.
In October 1961, Herbert Hovey, an electrical engi-
neer with ASA, and several colleagues visited Vietnam
to gain first-hand knowledge of the problem and local
conditions.
To work out the technical challenges of an airborne
DF system, Hovey and his team chose the U-6 BEA-
VER, a single-engine aircraft that could carry enough
equipment and a crew to man it. The team then solved
how the system could discriminate between direct
and sky radio waves and how to decouple the antenna
from the metal skin of the airplane. They also devel-
oped techniques whereby the DF operator and the pilot
could gain the most accurate bearings.
In March 1962, Hovey and his team returned to
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Vietnam with the airborne radio direction finding In July 1967, the battalion reached its highest
(ARDF) equipment in their luggage. The team im- strength with 1,066 personnel and 80 aircraft. In addi-
mediately installed the equipment on three available tion to aerial direction finders, these aircraft included
BEAVER airplanes. VHF and HF interceptors and electronic warfare jam-
mers.
Within a month, the 3rd RRU had plans to use the
new systems in locating and identifying Viet Cong By mid-1968, 224th assets were contributing nearly
communications that controlled enemy activity in the 4,000 fixes a month to the ground war. Usually used
South. In May, South Vietnamese forces destroyed an as a warning mechanism of pending enemy activity,
enemy command post based on locations gleaned from these fixes helped protect fire support bases and iso-
four days of ARDF collection. lated outposts and often led to targeted air strikes or
artillery fire.
The advantages of airborne collection over ground-
based sites quickly became clear. An airborne operator The 224th crews warned an American convoy of a
and equipment could get close enough to the enemy possible ambush when they discovered an enemy trans-
transmitter with reasonable security, allowing for more mitter with sufficient time for the convoy commander
accurate locations. to react. In one case, the 224th intercepted elements of
the North Vietnamese 1st Division and its plans for an
Since the airborne systems could cover a large area attack in February 1969. Nevertheless, ARDF proved
relatively quickly, they proved more responsive to the most effective when combined with other sources such
needs of the tactical commander in a fluid and mobile as documents, interrogation, aerial photography and
situation. patrols.
Within a year of the introduction of the ARDF sys- In 1971, the battalion began drawing down its pres-
tems, the 3rd RRU was presented with a Meritorious ence in Vietnam, inactivating the 144th Aviation Com-
Unit Commendation — the first unit to be so decorated pany in September 1971 and the 1st RR Company and
in Vietnam. the 156th Aviation Company six months later.
By 1965, ASA had grown its ARDF capability from For the final 10 months, the 138th and 146th com-
three to 30 aircraft. The larger air fleet needed a more panies continued to operate. On Feb, 16, 1973, an air-
robust command and support structure; consequently, craft from the 138th flew the final battalion mission in
on June 1, 1966, the ASA activated the 224th Aviation the vicinity of Pleiku. Two weeks later, the battalion
headquarters and the final two companies had been in-
activated.
When first established, the 224th consisted of four
subordinate aviation companies, with each company From June 1966 to March 1973, the 224th Aviation
directly supporting one of the Corps Tactical Zones in Battalion (RR) had participated in 15 campaigns and
South Vietnam: the 138th at Da Nang in the northern earned three Meritorious Unit Citations and a Viet-
zone, the 144th and 146th from Nha Trang and Saigon, namese Cross of Gallantry with Palm.
respectively, in the center zones, and the 156th in Can
Tho in the southern zone. (Editor’s Note: This article is the sixth in a series
on Military Intelligence in Vietnam marking the 50th
A year later, the 1st Radio Research Company (Avi- anniversary of the commitment of American combat
ation) deployed to Vietnam in direct support of U.S. troops to South Vietnam. It is a combination of two ar-
Military Assistance Command-Vietnam, or MACV. ticles published in the June and July 2010 issues of
The 224th headquarters and staff were stationed near INSCOM’s online INSIGHT journal.)
its parent unit, the 509th Radio Research Group, on
Tan Son Nhut Air Base in Saigon.