9-Line CAS Brief: Ingress, Target, and Terminal Attack Control

The 9-line CAS brief is the standardized radio format a ground controller uses to pass a close air support target to an attacking aircraft. Nine numbered pieces of information move in a fixed order, from where the aircraft begins its run to where it should fly after weapon release. Every U.S. service uses the same format, and Joint Publication 3-09.3 governs it.¹

Before the Brief: Aircraft Check-In

The 9-line does not start cold. When the attack aircraft arrives on station, it checks in with the controller and passes a standard set of data: mission number, number and type of aircraft, position and altitude, ordnance on board, time on station (reported using the brevity code PLAYTIME in hours and minutes), and abort code.²

The controller uses that information to build a game plan. Precision-guided munitions against a point target produce a different attack geometry than unguided rockets against an area target, and time on station sets how long the controller has to work.

Lines 1–3: Ingress

The first three lines build a flight path from a known point to the target.

Line 1 is the Initial Point (IP) for fixed-wing aircraft or the Battle Position (BP) for helicopters. This is a pre-coordinated geographic reference already on the pilot’s map, and it marks where the attack run begins.³

Line 2 is the heading from that IP or BP to the target, as a magnetic bearing in degrees, plus any offset. An offset tells the pilot to stay left or right of the direct heading to avoid hazards, restricted airspace, or other aircraft in the stack.³

Line 3 is the distance from the starting point to the target. Units depend on the platform: nautical miles for fixed-wing, meters for rotary-wing.⁴ Start point, direction, distance. A precise vector, no guesswork.

Lines 4–6: Target

Lines 4 through 6 are the heart of the brief.

Line 4 is target elevation in feet above mean sea level. Pilots use this figure to calibrate weapon delivery and fuzing, and a small error shifts the impact point.

Line 5 is target description: type, quantity, and disposition. Something like “two wheeled vehicles in a tree line” or “single fortified fighting position.” The point is giving the aircrew enough detail to confirm they are looking at the right thing.³

Line 6 is the target coordinates, typically in Military Grid Reference System format or latitude and longitude. This is where most of the risk lives. A transposed digit or wrong grid zone can put ordnance on friendlies or civilians, which is why Line 6 is a mandatory read-back item.³

Lines 7–9: Marks, Friendlies, and Egress

Line 7 is the type of mark on the target or the controller’s position. In daylight this may be colored smoke, a white phosphorus round, or a laser spot. At night, infrared devices replace visible marks. Brevity codes cover the common IR methods: SPARKLE marks with a steady IR pointer, SNAKE oscillates that pointer in a figure-eight around the target when multiple IR sources clutter the scene, and PULSE flashes IR energy at a position without a constant beam.⁵

Line 8 is friendly location, given as a cardinal direction and distance from the target. This is the fratricide-avoidance line. If friendlies are 300 meters north of the target, the pilot knows not to pull off in that direction and can adjust the attack accordingly.³

Line 9 is egress: the direction and a control point for the aircraft to fly toward after weapon release. This keeps the aircraft off friendly positions, out of another aircraft’s pattern, and away from known air defense threats on the way out.³

The Remarks Section

The brief does not actually stop at Line 9. A remarks section follows the nine fixed fields as an open block for information that will not fit the numbered slots. It is not a formal tenth line.

Remarks commonly cover weather, terrain and friendly-fire hazards, restrictions on attack heading or weapon type, known surface-to-air threats, the abort code if it was not passed at check-in, ground beacon data, and bearing and range from a beacon to the target. Coordination items like the final attack heading or a time-on-target requirement to synchronize the strike with ground maneuver go here as well.

Transmission Rhythm and Read-Back

The 9-line is passed in a deliberate cadence: three lines at a time, with a pause between groups so the aircrew can copy the data, enter coordinates, and verify settings before the next group arrives.

After the full brief, the pilot reads back Lines 4 and 6 along with any restrictions. The requirement applies under every control type and is non-negotiable.¹ The logic is direct. Line 4 (elevation) and Line 6 (coordinates) determine where the weapon lands; restrictions define where it must not land. The pilot repeats them and the controller confirms.

For digitally guided attacks where the aircrew loads coordinates into the weapon or aircraft system, the read-back comes from the system’s stored data rather than from a handwritten card. That catches data-entry errors a verbal read-back of notes would miss.¹

Once read-back is confirmed and the pilot has the target in sight, the controller issues clearance. The brief is not supposed to change after the aircraft departs the IP or BP inbound. If conditions shift after that point, the controller aborts the attack rather than amending the brief mid-run.¹

Types of Terminal Attack Control

How much oversight the controller keeps during the run depends on which of three control types is in effect. The choice comes from a tactical risk assessment weighing friendly proximity, visibility, and target certainty.

Type 1 is the most restrictive. The controller must visually acquire both the target and the attacking aircraft before clearing the pass. Used when friendlies are close, the situation is complex, or risk tolerance is low.⁶
Type 2 covers cases where the controller still clears each attack individually, but at least one of the Type 1 visual requirements cannot be met. The controller or an observer sees the target visually or through sensors, but the controller may not have eyes on the aircraft at release.⁶
Type 3 is the least restrictive. The controller grants blanket clearance for multiple attacks within a single engagement, subject to stated restrictions. Neither aircraft nor target visual acquisition is required of the controller. Used when the risk assessment shows a low probability of fratricide, typically against targets well separated from friendlies.⁶

Clearance language tracks the control type. Under Type 1 and Type 2, the controller issues “Cleared Hot” for each individual pass. Under Type 3, “Cleared to Engage” covers multiple attacks meeting the stated restrictions.⁶ The wrong phrase for the wrong control type is a procedural violation.

Danger Close

When friendly forces are inside the 0.1 percent probability of incapacitation distance for the weapon being employed, the situation is danger close. The supported ground commander must personally accept the risk, and the commander’s initials are passed to the attacking aircraft as confirmation that acceptance came from the command level, not just from the controller.⁷

Separately, when friendlies are within one kilometer of the target, the controller should treat the situation as troops in contact and advise the ground commander, regardless of whether the formal danger close threshold is crossed.⁷ The exact danger close distance varies by munition and comes from risk-estimate distance tables that account for blast radius, fragmentation, and delivery accuracy.

Not the Same as the MEDEVAC 9-Line

Two different 9-line formats exist in military operations, and they share nothing beyond the name. The CAS 9-line described here directs aircraft onto a target. The MEDEVAC 9-line requests a medical evacuation helicopter and carries different fields entirely: pickup location, radio frequency and call sign, number of patients and urgency, special equipment, whether patients are ambulatory, security at the landing zone, marking method, patient nationality and status, and any contamination or terrain concerns.⁸ One brings firepower, the other brings medical care, and the formats are not interchangeable.

1
Berlin Information-center for Transatlantic Security. JP 3-09.3 – Close Air Support
2
DOD Command and Control Research Program. Using SPOTTR to Enhance C2 in a Close Air Support Scenario
3
Marine Corps Base Camp Pendleton. FAC JTAC Class Handout
4
Public Intelligence. Multi-Service Tactics, Techniques, and Procedures for the Joint Application of Firepower (JFIRE)
5
Air Land Sea Space Application Center. Multi-Service Tactics, Techniques, and Procedures for Multi-Service Brevity Codes
6
Marine Corps Training Command. Aviation Employment Considerations
7
Marine Corps Training Command. MCWP 3-23.1 Close Air Support
8
DVIDS. All Nine Lines: How Terminology Can Save a Life Using a 9-Line Process