In
military tactics,
close
air support (
CAS) is defined as air
action by fixed or rotary winged aircraft against hostile targets
that are in close proximity to friendly forces, and which requires
detailed integration of each air mission with fire and movement of
these forces.
Joint Tactics,
Techniques, and Procedures for Close Air Support (2003).
DoD.
The determining factor for CAS is detailed integration, not
proximity. CAS may need to be conducted not in close proximity to
friendly forces, if the mission requires detailed integration with
the fire and movement of these forces. A closely related subset of
air interdiction,
battlefield air interdiction
denotes
interdiction against units
with near-term effects on friendly units, but which does not
require integration with friendly troop movements. The term
"battlefield air interdiction" is not currently used in US joint
doctrine.
Close air support requires excellent coordination with ground
forces. In advanced modern militaries, this coordination is
typically handled by specialists such as
Joint Fires Observers,
Joint Terminal Attack
Controllers (JTAC)s, and
Forward Air Controllers (FAC).
History
World War I
The use of aircraft in the close air support of ground forces dates
back to
World War I, the first
significant use of aerial units in warfare. Air warfare, and indeed
aviation itself, was still in its infancy - and the direct effect
of rifle calibre machine guns and light bombs of World War I
aircraft was very limited compared with the power of (for instance)
a World War II fighter bomber, but close support aircraft still had
a powerful psychological impact. The aircraft was a visible and
personal enemy - unlike artillery - presenting a personal threat to
enemy troops, while providing friendly forces assurance that their
superiors were concerned about their situation. Most successful
attacks of 1917 - 1918 included planning for co-ordination between
aerial and ground units, although it was very hard at this early
date to co-ordinate these attacks due to the primitive nature of
air-to-ground radio communication. Though most airpower proponents
sought independence from ground commanders and hence pushed the
importance of interdiction and strategic bombing, they nonetheless
recognised the need for close air support.
The British
Royal Flying Corps
and the
U.S. Army Air Service saw "trench strafing"
(as CAS was known) as another task for ordinary pursuit or fighter
aircraft, such as the
DH.5 and
Sopwith Camel, and did not seek out
specialized units or equipment until the late months of the war.
The first British specialised CAS aircraft, the
Sopwith Salamander, was too late to see
action. Since pilots lacked specific training, and their aircraft
were both slow and fragile, they suffered heavy casualties while
flying low over enemy positions. For example,
No. 80
Squadron RAF averaged 75% losses for the last 10 months of the
war. The Germans and French, however, developed tactics, training,
and formations for ground support. Germany also built specialist
CAS aircraft, culminating in the well armoured
Junkers J.I. By spring 1918, Germany had 38
Schlachtstaffeln (battle squadrons, often abbreviated to
Schlasta) trained to bomb and
strafe below 200 feet in support of ground forces..
Inter-War period - Framing the debate
During the inter-war period, airpower advocates crystallized their
views on the role of airpower in warfare. Aviators and ground
officers developed largely opposing views on the importance of CAS,
views that would frame institutional battles for CAS in the 20th
century. The inter-war period also saw the use of CAS in a number
of conflicts, principally Spain and China and the
Banana Wars. Observers and participants from the
major parties of
World War II would
base their CAS strategies on experience and observation from these
conflicts.
The development of the close air support came in between the World
Wars, mostly through the adaptation of
fighter or
light
bombers. Following the end of World War I, the United States
embraced its role of global power and the
United States Marine Corps became
the preferred force for military intervention and where the Marines
went so went
Marine
aviation.
It was while fighting bandits and insurgents
in places such as Haiti
, the
Dominican
Republic
and Nicaragua
that Marine Aviators would begin to experiment with
air-ground tactics making the support of their fellow Marines on
the ground their primary mission. It was in Haiti that U.S.
Marines began to develop the tactic of
dive
bombing and in Nicaragua where they began to perfect it. While
other nations and services had tried variations of this technique,
Marine aviators were the first to embrace it and make it part of
their tactical doctrine.
Corum &
Johnson,
Small Wars, p. 23-40.
Aviators, who wanted institutional independence from the Army,
pushed for a view of airpower centered around interdiction, which
would relieve them of the necessity of integrating with ground
forces and allow them to operate as an independent military arm.
They saw close air support as both the most difficult and most
inefficient use of aerial assets. Close air support was the most
difficult mission, requiring identifying and distinguishing between
friendly and hostile units. At the same time, targets engaged in
combat are dispersed and concealed, reducing the effectiveness of
air attacks. They also argued that the CAS mission merely
duplicated the abilities of artillery, whereas interdiction
provided a unique capability.
Ground officers contended there was rarely sufficient artillery
available, and the flexibility of aircraft would be ideal for
massing firepower at critical points, while producing a greater
psychological effect on friendly and hostile forces alike.
Moreover, unlike massive, indiscriminate artillery strikes, small
aerial bombs wouldn't render ground untrafficable, slowing
attacking friendly forces.
World War II
World War II marked the universal acceptance of the integration of
air power into combined arms warfare as close air support. Although
the German
Wehrmacht led the way,
all the major combatants had developed effective air-ground
coordination techniques by the war's end.
Western Front
Luftwaffe
As a continental power intent on offensive operations, Germany
could not ignore the need for aerial support of ground operations.
Though the
Luftwaffe, like its
counterparts, tended to focus on strategic bombing, the
Luftwaffe was unique in its willingness to commit forces
to CAS.
In
joint exercises with Sweden
in 1934, the
Germans were first exposed to dive-bombing, which permitted greater accuracy
while making attack aircraft more difficult to track by
antiaircraft gunners. As a result,
Ernst Udet, chief of the
Luftwaffe s
development, initiated procurement of close support dive bombers on
the model of the U.S. Navy's
Curtiss
Helldiver, resulting in the famous
Junkers Ju 87 Stuka. Experience in
the
Spanish Civil War lead to the
creation of five ground-attack groups in 1938, four of which would
be equipped with
Stukas. The
Luftwaffe matched
its material acquisitions with advances in the air-ground
coordination. General
Wolfram von
Richthofen organized a limited number of air liaison
detachments that were attached to ground units of the main effort.
These detachments existed to pass requests from the ground to the
air, and receive reconnaissance reports, but they were not trained
to guide aircraft onto targets.
These preparations did not prove fruitful in the
invasion of Poland, where the
Luftwaffe focused on interdiction and dedicated few assets
to close air support.
But the value of CAS was demonstrated at the
crossing of the Meuse
River
during the Invasion of France in
1940. General
Heinz Guderian,
one of the creators of the combined-arms tactical doctrine commonly
known as "
blitzkrieg", believed
the best way to provide cover for the crossing would be a
continuous stream of ground attack aircraft on French defenders.
Though few guns were hit, the attacks kept the French under cover
and prevented them from manning their guns. Aided by the sirens
attached to
Stukas, the psychological impact was
disproportional to the destructive power of close air support. In
addition, the reliance on air support over artillery reduced the
demand for logistical support through the Ardennes. Though there
were difficulties in coordinating air support with the rapid
advance, the Germans demonstrated consistently superior CAS tactics
to those of the British and French defenders. Later, on the Eastern
front, the Germans would devise visual ground signals to mark
friendly units and to indicate direction and distance to enemy
emplacements.
Despite these accomplishments, German CAS was not perfect and
suffered from the same misunderstanding and
interservice rivalry that plagued other
nations' air arms, and friendly fire was not uncommon. For example,
on the eve of the Meuse offensive, Guderian's superior cancelled
his CAS plans and called for high-altitude strikes from medium
bombers, which would have required halting the offensive until the
air strikes were complete. Fortunately for the Germans, his order
was issued too late to be implemented, and the
Luftwaffe
commander followed the schedule he had previously worked out with
Guderian. As late as November 1941, the
Luftwaffe refused
to provide
Erwin Rommel with an air
liaison officer for the
Afrika
Korps, because it "would be against the best use of the
air force as a whole."
Royal Air Force and U.S. Army Air Forces
The Americans and British entered the war woefully unprepared to
provide CAS. In 1940, the
Royal Air
Force and Army headquarters in France were located at separate
positions, resulting in unreliable communications.
After the RAF was
withdrawn in May, Army officers had to telephone the War Office
in London to arrange for air support. The
stunning effectiveness of German air-ground coordination spurred
change.
On
the basis of tests in Northern Ireland
in August 1940, Group
Captain A. H. Wann RAF and Colonel J.D. Woodall (British
Army) issued the Wann-Woodall Report, recommending the creation of
a distinct tactical air force and liaisons (known colloquially as
"tentacles"), to accompany Army divisions and brigades. Their
report spurred the RAF to create an
Army Co-Operation Command and to
develop tentacle equipment and procedures placing an Air Liaison
Officer with each brigade.
Charged with the principal mission of strategic bombing, the U.S.
Army Air Forces (AAF) operated independently of the rest of the
Army. AAF doctrinal priorities for tactical aviation were, in
order, air superiority, isolation of the battlefield via supply
interdiction, and thirdly, close air support. However, in 1944, in
response to the success of the
Stuka and German CAS, AAF
commander Lt. Gen.
Henry Arnold
acquired 2 groups of
A-24 dive
bombers, the army version of the Navy's SBD-2. Later, the AAF would
develop a modification of the
P-51
Mustang with dive brakes - the
North American A-36. However, there was
no training to match the purchases. Though Gen. Lesley McNair,
commander of Army Ground Forces, pushed to change AAF priorities,
the latter failed to provide aircraft for even major training
exercises.
Six months before the invasion of
Normandy
, 33 divisions had received no joint air-ground
training. In 1943, the AAF changed their radios to a
frequency incompatible with ground radios.
As a result, CAS was poorly executed, if at all, by the AAF in the
North African campaign. So few aerial assets were assigned to U.S.
troops that they fired on anything in the air. While the RAF sorted
out its CAS doctrine in London, officers in North Africa improvised
their own coordination techniques. In October 1941,
Sir Arthur Tedder and
Arthur Coningham,
senior RAF commanders in North Africa, created joint RAF-Army Air
Support Control staffs at each corps and armored division
headquarters, and placed a Forward Air Support Link at each brigade
to forward air support requests. When trained tentacle teams
arrived in 1942, they cut response time on support requests to
thirty minutes. It was also in the North Africa desert that the
cab rank strategy was developed. It used a
series of three aircraft, each in turn directed by the pertinent
ground control by radio. One aircraft would be attacking, another
in flight to the battle area, while a third was being refuelled and
rearmed at its base. If the first attack failed to destroy the
tactical target, the aircraft in flight would be directed to
continue the attack. The first aircraft would land for its own
refuelling and rearming once the third had taken off.
The situation would improve during the Italian campaign, where
American and British forces, working in close cooperation,
exchanged CAS techniques and ideas. There, the AAF's XII Air
Support Command and the Fifth U.S. Army shared headquarters,
meeting every evening to plan strikes and devising a network of
liaisons and radios for communications. However, friendly fire
continued to be a concern - pilots did not know recognition signals
and regularly bombed friendly units, until an A-36 was shot down in
self-defense by Allied tanks. Friendly fire from the ground
prompted the black and white stripes painted on all Allied aircraft
from 1944.
The AAF would see the greatest innovations in 1944 under Gen.
Elwood Quesada, commander of IX
Tactical Air Command, supporting the First U.S. Army. He developed
the "armored column cover", where on-call fighter-bombers
maintained a high-level of availability for important tank
advances, allowing armor units to maintain a high tempo of
exploitation even when they outran their artillery assets. He also
used a modified antiaircraft radar to track friendly attack
aircraft to redirect them as necessary, and experimented with
assigning fighter pilots to tours as forward air controllers to
familiarize them with the ground perspective. In July 1944, Quesada
provided VHF aircraft radios to tank crews in Normandy. When the
armored units broke out of the Normandy beachhead, tank commanders
were able to communicate directly with overhead fighter-bombers.
However, despite the innovation, Quesada focused his aircraft on
CAS only for major offensives. Typically, both British and American
attack aircraft were tasked primarily to interdiction, even though
later analysis showed them to be twice as dangerous as CAS.
XIX TAC, under the command of General
Otto P. Weyland utilized similar tactics to support
the rapid armored advance of General
Patton's
Third Army in its drive across France. Armed reconnaissance was a
major feature of XIX TAC close air support, as the rapid advance
left Patton's Southern flank open. Such was the close nature of
cooperation between the Third Army and XIX TAC that Patton actually
counted on XIX TAC to guard his flanks. This close air support from
XIX TAC was thus undoubtedly a key factor in the rapid advance and
success of Patton's Third Army.
Soviet front
VVS RKKA
The
Red Air Force was not slow to
recognize the value of ground support aircraft.
Even as far back as
the Nomonhan
incident, Russian aircraft were given the task of
disrupting enemy ground operations. This use increased
markedly after the German invasion. Purpose-built aircraft such as
the
Ilyushin Il-2 Sturmovik
were highly effective in blunting the activity of the
Panzers. Joseph Stalin paid the Il-2 a great tribute in
his own inimitable manner: when a particular production factory
fell behind on its deliveries, Stalin sent the following cable to
the factory manager: "They are as essential to the Red Army as air
and bread."
German CAS reached its peak on the Eastern Front during the period
1941-1943. Their decline was caused by the growing strength of the
Red Air Force and the redeployment of assets to defend against
American and British strategic bombardment. The introduction of
improved Soviet tanks, the
T-34 and
KV-1 reduced the effectiveness of close air support,
even after the adoption of 30 mm cannon and shaped-charge
bombs. While German procedures for CAS led the way, their loss of
air superiority and technological advantage, combined with a
declining supply of aircraft and fuel, crippled their ability to
provide CAS after 1943.
The Pacific Theater
The American Navy and Marine Corps would similarly use CAS in
conjunction with or as a substitute for the lack of available
artillery or naval gunfire. Marine Corsairs used a variety of
ordnance such as conventional bombs, rockets and napalm to disloge
or attack Japanese troops utilizing cave complexes in the latter
part of WWII.
Korean War
F4U-5 Corsairs provide close air
support to U.S. marines fighting Chinese forces during the war in
Korea, December 1950.
From Navy experiments with the
KGW-1 Loon, the
Navy designation for the German V-1 flying bomb, Marine Captain
Marian Cranford Dalby developed the
AN-MPQ-14, a system that enabled radar-guided bomb
release at night or in poor weather.
Krulak,
First to Fight, p. 113-119
Though the Marine Corps continued its tradition of intimate
air-ground cooperation, the newly created Air Force again moved
away from CAS, now to strategic bombers and jet
interceptors. Though eventually the Air Force
supplied sufficient pilots and forward air controllers to provide
battlefield support, coordination was still lacking. Since pilots
operated under centralized control, ground controllers were never
able to familiarize themselves with pilots, and requests were not
processed quickly. Harold K. Johnson, then commander of
8th Cavalry Regiment, 1st Cavalry
Division (later
Army Chief of
Staff) commented regarding CAS: "
If you want it, you can't
get it. If you can get it, it can't find you. If
it can find you, it can't identify the target. If it can
identify the target, it can't hit it. But if it does hit
the target, it doesn't do a great deal of damage
anyway."
Blair (1987),
Forgotten
War, p. 577.
It's
unsurprising, then, that MacArthur
excluded USAF aircraft from the airspace over the Inchon
Landing
in September 1950, instead relying on Marine Aircraft Group 33 for
CAS. In December 1951, Lt. Gen.
James Van Fleet, commander of the
Eighth U.S. Army, formally requested the United Nations
Commander, Gen.
Mark Clark, to
permanently attach an attack squadron to each of the four army
corps in Korea. Though the request was denied, Clark allocated much
more Navy and Air Force aircraft to CAS. Despite the rocky start,
the USAF would also work to improve its coordination efforts. It
eventually required pilots to serve 80 days as
forward air controllers (FACs), which
gave them an understanding of the difficulties from the ground
perspective and helped cooperation when they returned to the
cockpit. The USAF also provided airborne FACs in critical
locations. The Army also learned to assist, by suppressing
anti-aircraft fire prior to air strikes.
The
U.S. Army
wanted a dedicated
USAF
presence on the battlefield to reduce
fratricide, or the harm of friendly forces. The
air liaison officer (ALO) was born. The ALO is an aeronautically
rated officer that has spent a tour away from the cockpit, serving
as the primary advisor to the ground commander on the capabilities
and limitations of
airpower.
Introduction of Helicopters
The 1960s and 1970s saw the adoption of
attack helicopters in the CAS role.
Though helicopters were initially armed merely as defensive
measures to support the landing and extraction of troops, their
value in this role lead to the modification of early helicopters as
dedicated gunship platforms. Though not as fast as fixed-wing
aircraft and consequently more vulnerable to anti-aircraft
weaponry, helicopters could utilize terrain for cover, and more
importantly, had much greater battlefield persistence owing to
their low speeds. The latter made them a natural complement to
ground forces in the CAS role. In addition, newly-developed
Anti-tank guided missiles,
demonstrated to great effectiveness in the 1973
Yom Kippur War, provided aircraft with an
effective ranged anti-tank weapon. These considerations motivated
armies to promote the helicopter from a support role to a combat
arm. Though the U.S. Army controlled rotary-wing assets,
coordination continued to pose a problem. During wargames, field
commanders tended to hold attack helicopters out of fear of air
defenses, committing them too late to effectively support ground
units. The earlier debate over control over CAS assets were
reiterated between ground commanders and aviators.
In the mid 1970s, after Vietnam, the USAF decided to train an
enlisted force to handle many of the tasks
the ALO was saturated with, to include
terminal attack control. Now the ALO
mainly serves in the liaison role, the intricate details of mission
planning and attack guidance left to the enlisted members of the
Tactical Air Control
Party.
Aircraft
Various aircraft can fill close air support roles.
Helicopters are often used for close air support
and are so closely integrated with ground operations that in most
countries they are operated by the army rather than the air force.
Fighter and ground attack aircraft
like the
A-10 Thunderbolt II
provide close air support using rockets, missiles, small bombs, and
strafing runs.
In World War II,
dive bombers and
fighters were used in close air
support. Dive bombing permitted greater accuracy than level bombing
runs, while the rapid altitude change made it more difficult for
antiaircraft gunners to track. The
Junkers
Ju 87 Stuka is the best known example of a dive bomber
designed for CAS. It was fitted with wind-blown whistles on its
landing gear to enhance its psychological effect.
Other than the A-36, a P-51 modified with dive brakes, the
Americans and British used no dedicated CAS aircraft in World War
II, preferring fighters or fighter-bombers that could be pressed
into CAS service. While some such as the
Hawker Typhoon and the
P-47 Thunderbolt, performed admirably in
that role, there were a number of compromises that prevented most
fighters from making effective CAS platforms. Fighters were usually
optimized for high-altitude operations without bombs or other
external ordnance - flying at low level with bombs quickly expended
fuel. Cannons had to be mounted differently for strafing - strafing
required a further and lower convergence point than aerial combat
did.
Of the World War II allies, the Soviet Union used
specifically-designed ground attack aircraft more than the UK and
US. Such aircraft included the
Ilyushin
Il-2, the single most produced military aircraft design in all
of aviation history.
In the
Vietnam War, the United States
introduced fixed-wing gunships, cargo aircraft refitted as gun
platforms to serve as close air support and air interdiction
aircraft. The first of these was the
AC-47
Spooky. Later models include the
Fairchild AC-119 and the
Lockheed AC-130. The AC-130 has been used
extensively in Afghanistan and Iraq during recent US operations
there.
Today, close support is typically carried out by fighter-bombers or
dedicated ground attack aircraft, such as the
A-10 Thunderbolt II Warthog or
Sukhoi Su-25 Frogfoot, but
even large high-altitude bombers can occasionally fill close
support roles using
precision
guided munitions. During
Operation Enduring Freedom, the
lack of fighter aircraft forced military planners to rely heavily
on US bombers, particularly the
B-1 and
B-52 Stratofortress, to fill the
CAS role. Bomber CAS, relying mainly on
GPS guided weapons, has evolved
into a devastating tactical employment methodology and has changed
US doctrinal thinking regarding CAS in general. After the initial
collapse of the
Taliban regime in
Afghanistan, airfields in Afghanistan became available for
continuing operations against the Taliban and
Al-Qaeda. This resulted in the majority CAS
operations to be undertaken by aircraft from Belgium (
F-16 Fighting Falcon), Denmark (F-16),
France (
Mirage 2000D),
the Netherlands (F-16), Norway (F-16), the United Kingdom (
Harrier GR7s and GR9s) and the United States
(A-10,
AV-8B Harrier II,
F/A-18 Hornet).
Technological enhancement
The use of information technology to direct and coordinate
precision air support has increased the importance of
intelligence,
surveillance, and
reconnaissance in utilizing CAS.
Laser,
GPS, and battlefield data
transfer are routinely used to coordinate with a wide variety of
air platforms able to provide CAS. Recent doctrine reflects the
increased use of electronic and optical technology to direct
targeted fires for CAS. Air platforms communicating with ground
forces can also provide additional aerial-to-ground visual search,
ground-convoy escort, and enhancement of command and control (C2),
assets which can be particularly important for
low intensity conflict.
Haun (2006),
Air & Space Power
Journal.
See also
Notes
- Hallion (1990),
Airpower Journal.
- House (2001),
Combined Arms Warfare.
References
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