3 - 3 WARNING [Commanders] use RED formulas to determine acceptable risk levels in combat only. Specifically, use them to identify the risk to your Rangers at various distances from their targets. Risk estimate distances apply only in combat. In training, use minimum safe distances (MSD). a. Casualty Criterion. The casualty criterion is the 5 minute assault criterion for a prone Ranger in winter clothing and helmet. Physical incapacitation means that a Ranger is physically unable to function in an assault within a 5 minute period after an attack. A PI value of less than 0.1 percent can be interpreted as being less than or equal to one chance in one thousand. Table 3-3. RISK ESTIMATE DISTANCES FOR MORTARS AND CANNON ARTILLERY Risk Estimate Distances (Meters) 10 % PI 0.1 % PI Description 1/ 3 Range 2/ 3 Range Max Range 1/ 3 Range 2/ 3 Range Max Range 60-mm mortar 60 65 65 100 150 175 81-mm mortar 75 80 80 165 185 230 120-mm mortar 100 100 100 150 300 400 105-mm howitzer 85 85 90 175 200 275 155-mm howitzer 100 100 125 200 280 450 155-mm DPICM 150 180 200 280 300 475 b. Risk. Using echelonment of fires within the specified RED for a delivery system requires the unit to assume some risks. The maneuver commander determines by delivery system how close to his forces he will allow fires to fall. Although he makes the decision at this risk level, he relies heavily on the FSO's expertise. 3-6. TARGET OVERLAYS a. Fire Support Overlay. Figure 3-1 shows contents of fire support overlay. (1) Non Sterile Fire Support Overlay (Figure 3-2). (2) Sterile Fire Support Overlay (Figure 3-3). This includes– (a) Index marks to position overlay on map (b) Target symbols • Point target • Linear target • Circular target Figure 3-1. CONTENTS OF FIRE SUPPORT OVERLAY Unit and official capacity of person making overlay Routes – primary and alternate Date the overlay was prepared Phase lines and checkpoints used by the patrol Map sheet number Spares Effective period of overlay (DTG) Index marks to position overlay on map Priority target Objective ORP location Target symbols Call signs and frequencies (PRI/ ALT) Description, location and remarks column, complete