3. CLOSE AIR SUPPORT.
a. Introduction. This section will address those CAS missions that are flown in proximity to friendly forces and require integration of the air mission with the fire and maneuver of ground commanders. In the eyes of the ground commander, the most significant of these missions are support of engaged forces, helicopter landing zone preparation, pre-strike troop airlift cover, and road convoy escort. Missions for harassment, interdiction, area neutralization, or support of future operations will be included in a later section.
b. Operation of the CAS System.
(1) To furnish the integrated TACAIR support needed daily by ground commanders, CAS missions are provided as either preplanned or immediate. Requests for either type are processed through the JAGOS, as established by MACV, to provide an integrated command and control system. The JAGOS is shown below, in Figure C-7 and includes the AAGS and the AF TACS. The RVN is blanketed by UHF, VHF, and HF control and reporting nets, land lines, and secure teletype. All secure communications are available from the COC in the TACC to the corps DASCs and down to the ALOs, FACS, strike bases, and radar sites.
Figure C-7 : MACV Joint Air-Ground Operations System (JAGOS)
(2) Because of intermingling of friendly forces, local population, and enemy forces, all strikes in the RVN must be approved by a province chief or higher RVN authority. For normal US/FWMAF operations, this approval is usually granted in advance to ground commanders for their areas of responsibility. This advance approval helps to minimize delays in processing requests for CAS to engage forces.
(3) There are 8 fighter wing equivalents in the RVN, including the VNAF and USMC units. In addition, there are squadron-size units and USN carriers which have tactical fighters. These wings, squadrons and carriers have the following type aircraft:
Typical tasking of these forces has often provided over 300 preplanned sorties daily, plus immediates. Preplanned and immediate sorties typically total over 12,000 monthly in direct support of ground commanders.
c. Preplanned Strikes.
(1) Preplanned requests for TACAIR support originate with the ground commanders, based on their plan of maneuver. Requests may originate at any level, but must be approved up the chain of command to corps level.
(2) The Vietnamese province chief concerned must approve each request. This approval is secured at the division level for requests coming up the AAGS. In many cases, the ground commanders are granted advance approval for a specific area. In the ARVN structure, the province chief examines requests from his various districts and forwards those he approves to corps.
(3) Approved requests for US and FWMAF TACAIR, listed in order of priority, are forwarded by the US advisors to the ARVN Corps, US FFORCEVs, and XXIV Corps to the MACV J-3 TASE in the TACC. The TASE, made up of elements of MACV J-2 and J-3, is staffed with US Army personnel and is the final authority for approving requests and assigning priorities, guided by overall MACV requirements. The TASE is the body through which COMUSMACV approves and assigns priorities to all CAS requests and then levies CAS tasks to be executed by USAF, USMC, and, when available, USN aircraft. The execution of these tasks is planned, directed, and controlled through the TACS, which functions under the supervision of the Commander, 7AF in his capacity as MACV AF Component Commander and as DEPCOMUSMACV for Air Operations.
(4) Those strike requirements received by the TASE from ARVN Corps advisors are to fill requirements which the VNAF cannot accomplish. The ARVN corps commanders control the VNAF aircraft in their CTZs and specify which requests will be supported by VNAF aircraft. The VNAF Strike Plans Branch, in the TACC, issues the VNAF frag order for all CTZs.
(5) The targets passed to the TACC by the TASE are a levy to be satisfied within the limits of aircraft available. The requirements are passed to the Strike Plans Branch in the. TACC where they are matched with aircraft available for the following day. The strike planners then prepare the frag orders which task the fighter wings with the missions.
d. Typical Preplanned CAS Strike.
(1) A typical Army-requested preplanned strike might start at the battalion level. The brigade is planning a search-and-clear operation and a battalion commander needs an air strike for LZ preparation for a helicopter assault. The brigade ALO has reconnoitered the LZ area to determine the most effective ordnance for the mission. In selecting the ordnance, the ALO considers such factors as the area to be covered, the nature of the terrain, the tree trunk size, and the type and density of the canopy. In some cases, it is the ALO who recommends to the ground commander that an air strike be requested for a specific purpose.
(2) The brigade commander also has several other air strike requests for the following day. For each request, the grid coordinates, desired ordnance, TOT, latest TOT, a brief target description, and desired results are listed. The requests are then numbered in order of priority and sent to division. The division list is passed to FFORCEV, again consolidated with other lists, and sent to the MACV TASE. A TACP is located at the brigade TOC and at each higher TOC. As the request is forwarded, it is examined by the ALO at each level.
(3) The original battalion request for an LZ preparation air strike is still high on the consolidated list sent to the MACV TASE, is approved there, and sent to the TACC, still with a high priority. The request, along with others for the next day, arrives at the Strike Plans Branch of the TACC. The strike planners determine the number and type of aircraft, the ordnance, TOT, and rendezvous point with the FAC for each strike. The Strike Plans Branch then consolidates the preplanned strikes into the daily frag order and sends it to all interested agencies. The DASC passes the information to the division ALOs who radio the targets to the various FACS. In this way, the FAC learns during the early evening what preplanned strikes he will be directing the next day.
(4) The frag is received by the tasked aircraft wings the evening before the strikes and the aircraft are armed with the specified munitions.
(5) On the day of the mission, the FAC takes off, calls the TACP at his takeoff location that he is airborne, and calls the TACP serving the commander who requested the strike to advise him that he is on the way to the target. The FAC also determines if there has been any change in the TOT, grid coordinates, etc. He checks with weather, then calls the AASWCC for information on artillery fire in order to clear himself and to plan a safe approach for the strike aircraft.
(6) He may also call the S-3 Air of the unit requesting the strike for the detailed target description. The original request may have been only in general terms and provided a six-digit (100 m square) grid location. The FAC can place the fire much more precisely if he can get a specific target description, such as, "250 meters north of the white boulder upstream from the fording site." Under NO circumstances, should the numerical grid be given in the clear earlier than one hour before TOT; if possible, not more than 20 minutes before TOT is preferable. In some cases, the FAC may have to be given the call sign and frequency of a company commander far out in the "boonies" to get the detailed target description.
(7) There may be several artillery clearances the FAC has to obtain - division, brigade, and battalion (even two battalions, if the target is less than 1000 meters from the boundary between the battalions). From each of these, the FAC must get friendly locations, confirmation of target grid, and clearance to expend.
(8) Now the FAC is ready to contact the ground commander with whom he will be working. Normally, he is the ground commander of the closest friendlies. The FAC obtains from him the latest location of the closest friendlies, the scheme of maneuver, and specifically what the ground commander wants from the strike aircraft ordnance. The FAC gives him the latest information on when to expect the strike; has him stand by to mark his position; and, if necessary, advises him to have his troops take cover (depending on the ordnance to be used and the distance from the friendlies to the target). The ground commander will appreciate knowing what kind of strike aircraft are on the way, what kind of ordnance they will use, and in what direction they will be working.
(9) Sometimes the ground commander will be directing his forces from a helicopter and may want to mark the target himself. In these cases, the airborne ground commander can assess damage between strikes, mark new targets, and assess total damage. The FAC should let the ground commander know on what UHF frequency the strike aircraft will be handled so that he can monitor FAC directions.
(10) Meanwhile, the strike pilots have been briefed on the mission and the weather and have taken off. They are controlled by the CRCs and CRPs until about five minutes before reaching the rendezvous point with the FAC, at which time they switch to the FAC frequency. The FAC insures that he is on the designated frequency 15 minutes or more before the rendezvous time. As soon as he has contacted the strike aircraft he switches them to another frequency. The FAC monitors all his radios - TACP on VHF, strike aircraft on UHF, and ground commander on FM - so that he can receive instruction from various sources to cease fire or change target.
(11) When he contacts the strike aircraft the FAC ascertains their mission number, altitude, position, number of aircraft, amount and types or ordnance, and the maximum time they can remain in the area. He describes the target to the strike pilots, gives them a clear route of approach, and tells them the location of both enemy and friendly troops. He establishes attack and break-off headings which will prevent over-flying friendly troops when delivering ordnance and he determines the sequence of ordnance delivery. This exchange of information between the FAC and pilots is essential to effective delivery of ordnance with minimum risk to the FAC, pilots, and friendly ground forces.
(12) When the strike aircraft are overhead and visual contact is clearly established, the FAC has the ground commander mark his location. When the friendly positions are firmly outlined, the FAC marks the target with his rockets (or clears the ground commander in his helicopter to mark), and clears the strike aircraft in. He transmits specific clearance to expend to each aircraft on each individual pass when he is sure that the aircraft is properly aligned on target.
(13) The FAC must position himself so that he can always see both the strike aircraft and the target. After the first pass, he directs later passes to insure adequate target destruction. One of the most effective methods is to adjust from the last ordnance drop; corrections are given in meters and direction from the last impact. The FAC has the responsibility to approve or disapprove the strike, but this does not relieve the strike pilots of the responsibility to abort the strike if they see a potentially dangerous situation develop.
(14) After expending their ordnance, the strike aircraft hold "high and dry" out of enemy range and receive a BDA report from the FAC. When released by the FAC, the strike flight forms and leaves the FAC frequency to re-establish radar contact for the flight to home base. Upon return to base, the pilots go directly to an intelligence debriefing to relate information on type target, tactics used, ground fire received, BDA, and other significant data. The FAC passes BDA to the TACP associated with the ground commander supported. This TACP passes the BDA to the DASC who routes it to 7AF intelligence. (See Figure C-15 and Figure C-16 and Appendix 1 for more information on preplanned strike procedures.)
e. Immediate Strikes.
(1) It is not possible for the ground commander to know precisely how the battle will evolve or when he may meet unexpected opposition. Thus, there is another type requirement for CAS – the immediate strike requirement. The same basic approval process takes place for immediate requests as for preplanned ones, except that it is at a much more rapid pace.
(2) Immediate requests are sent through the AF request net directly to the DASC, as shown in Figure C-17. Each higher level of the Army command monitors these requests through its respective TACP, remaining silent if the request is approved. If the request can be satisfied by weapons available to a higher commander, the request is disapproved and the requesting commander is advised of the support to be furnished. When an immediate strike is requested by RVNAF, it is initially forwarded to the province chief, who passes it to corps where it is handed to the DASC.
(3) When the request is approved at corps (ARVN) or FFORCEV or XXIV Corps (US) level it becomes mandatory for the DASC to fulfill the requirement. The DASC may divert an airborne flight in the corps area to meet the call for immediate help or request the TACC to divert strike aircraft from an adjacent corps area or to scramble ground alert aircraft. (Recall that I DASC is allocated scramble aircraft and need only inform the TACC of their launch.) Normally, aircraft are kept on ground alert at all strike bases to respond to immediate requests. They are usually able to arrive over any target in the RVN in less than 40 minutes after the ground commander has requested them. This response time is adequate for the average tactical situation as it usually takes a ground commander about that long to determine friendly positions and the extent of enemy opposition.
(4) To illustrate the immediate strike sequence of events, assume that a US infantry battalion is operating north of Pleiku, when it is suddenly engaged by what is estimated to be major elements of an NVA regiment known to be operating in the area. The battalion is receiving heavy weapons fire and is pinned down. At the brigade TOC, the ALO has the TACP radio operator call the DASC, requesting an immediate air strike. The DASC diverts an allocated preplanned strike to satisfy the requirement. In addition, the ALO has called either an airborne or ground alert FAC to advise him of the mission. The control of the strike aircraft to the rendezvous point, the duties of the FAC, and the execution of the strike are generally identical to the sequence of events during a preplanned strike - with two noteworthy exceptions on the part of the FAC.
(a) First, his initial task is establishing the location of friendly and enemy troops. Since many enemy attacks occur at night, and much intermingling and movement of ground forces may take place, the problem of sorting out who is where can be particularly difficult for both the ground commander and the FAC.
(b) Secondly, the FAC must be quick to assess the overall situation as to whether more strikes are needed. If so, the FAC radios either the division or brigade TACP who passes the request to the appropriate DASC. See Figure C-17 and Figure C-18 for more information on immediate strikes.
f. CAS at Night.
(1) Night operations make up a major part of combat actions in the RVN. The enemy launches most of his attacks at night, both against regular troop units and against small provincial outposts - against the small outposts in particular.
(2) There is a weapons system specifically designed to counter this night threat. This is the AC-47, known as ‘Spooky', a World War II transport aircraft (the C-47 "Sky Train"), modified by adding three side-firing 7.62 miniguns, each capable of firing 6000 rounds per minute. It also carries 25 flares, each of 2,000,000 candlepower. The AC-119 "Shadow" and the AC-119 "Stinger" are other gunships with similar missions. The Stinger is the later Model K AC-119. In addition to the armament of the Shadow, it has two 20mm multi-barrel guns which can fire 2500 HE incendiary rounds per minute; its illuminator is 2,000,000,000 candlepower.
(3) Each night these aircraft orbit bases strategically located throughout the RVN. These aircraft can provide support to the ground commander almost anywhere in the RVN in a matter of minutes. Other gunships are on ground alert.
(4) Each of the provincial outposts is tied to the province (sector) headquarters by radio, either directly or through the district (subsector) post. If an outpost needs air support, it sends a request to the province chief, who contacts the corps TOC. While the request is being coordinated by ARVN G-3 Air at the DASC (DASCs are collocated, with the corps TOCS), the DASC contacts the orbiting gunship through the appropriate CRC/CRP and diverts it to the scene. The DASC passes the coordinates and radio frequency of the ground commanders. While the airborne alert aircraft is enroute to the scene, a ground alert gunship takes off to replace it in orbit.
(5) As soon as the request is approved, the gunship is cleared to fire once FM radio contact is established with the ground commander or outpost. This contact is maintained through a Vietnamese observer aboard the gunship. When it arrives on the scene, it drops flares to light the target. If the ground commander has troops in contact and asks for fire support, the Spooky is authorized to provide it. The miniguns, mounted in the fuselage and pointed almost parallel to the wing, are used to strafe the enemy while Spooky orbits and continues to drop flares.
(6) In addition to Spooky gunships, strike aircraft are kept on strip alert for action where heavier fire support is required. When these aircraft are scrambled, the Spooky will act as a flareship to light the target for their attack. Frequently, the aircraft and flares over the scene, even without firing, will cause the enemy to break off the attack.
(1) A wide variety of ordnance is available for CAS operations in the RVN. The most frequently used are the general purpose high explosive bombs, commonly referred to as "iron bombs". The BLU antipersonnel and anti-material weapons and the many CBU types are also used frequently. Many aircraft use the highly-effective 2.75 inch rockets, 20mm cannon, 7.62 mm miniguns, and .50 caliber machine guns.
(2) General purpose bombs are used when penetration is desired, as against bunkers or caves. The CBU weapons are used against troops in the open, particularly for linear targets such as enemy along canals. Because of the delivery accuracy of most BLU weapons, they are used against a variety of targets, including those in the immediate vicinity of friendly forces.
(3) The 2.75 inch rocket is used against poorly-defined "soft" targets, such as those found during the escort of herbicide or cargo-drop aircraft when the exact enemy position is not known. The 20m cannon is a formidable weapon, highly desired by closely-engaged ground commanders because of the accuracy which can be brought to bear on the enemy.
(4) Preplanned strikes are fragged for specific ordnance; loads of all munitions types are available on aircraft standing strip alert for immediate strikes. Many types of ordnance are effective against a variety of targets; this makes effective ordnance delivery much easier.
(5) See Appendix 2 for additional data on air munitions.
Vietnam Lessons Learned No. 77: Fire Support Coordination in the Republic of Vietnam. United States Military Assistance Command, Vietnam, 20th May 1970