Deliberate Range Determination Methods... 7-5
Immediate Range Determination Methods
RECOGNITION METHOD
With practice, range determination by recognition is quick and accurate; however, this method will not work with passive or thermal sights. The principle of the recognition method is simple. When the TC sees a target, he can determine the range according to what he recognizes. For example, if a target can be recognized as a tank with the unaided eye, it is within 1,500 meters; if a target can be recognized as a tank through magnifying optics (GAS, binoculars, and so forth), it is within 5,000 meters.
The following table gives range estimations for targets as seen with the unaided eye and through magnifying optics (binoculars).
RANGE DETERMINATION RECOGNITION METHOD
Target
Unaided Eye (meters)
Magnification 7 or 8 Power (meters) Tank crew, troops, machine gun, mortar, antitank
gun, antitank missile launchers 500 2,000 Tank, personnel carrier, truck, (by model) 1,000 4,000 Tank, howitzer, personnel carrier, truck 1,500 5,000 Armor vehicle, wheel vehicle 2,000 6,000
When using the recognition method, the size and clarity of the target in relation to its background must be considered. Some light and terrain conditions make a target seem closer; other conditions make it seem farther away. The conditions outlined in the following table may cause an error in estimating range by the recognition method.
TARGET CONDITIONS
Looking across ravines, hollows, rivers, depressions Desert
M1A2 COMMANDER'S INDEPENDENT THERMAL VIEWER STADIA RETICLE
The stadia reticle is displayed when the NFOV is selected using the FOV button on the CCHA, the CITV is in SEARCH mode, and the range/stadia reticle switch is pressed. The stadia reticle is used to determine the approximate range to tank-height targets when the LRF is inoperable, or the TC wishes to avoid traversing the turret to align the LRF. Range is determined by matching the apparent height of the target with the stadia reticle, which can be made smaller or larger by moving the range/stadia reticle switch.
• The range/stadia reticle switch will only operate the stadia reticle when the LRF is OFF, inoperable, or the CITV is in a non-GUN LOS state.
• The stadia reticle will only appear when in NFOV.
• There are 11 different reticle sizes that provide ranges from 500 meters to 3,630 meters.
• Moving the range/stadia reticle switch backward will increase the size of the stadia reticle. Moving the range/stadia reticle switch forward will decrease the size of the stadia reticle.
• The stadia reticle will disappear from view after 10 seconds if the range/stadia reticle switch is not used. The last range input will remain displayed.
• The stadia reticle is most accurate when used with tank-height targets. Ranges to targets that are of different heights will be inaccurate.
• When the stadia reticle is used, the range will be input into the fire control system once the DESIGNATE button is pushed.
To determine the range to a full-height target, move the range/stadia reticle switch forward or backward until the bottom index line rests on the bottom of the target and the top index line rests on the top of the target.
The approximate range is displayed on the CITV display.
To determine the range to a hull-down target, move the range/stadia reticle switch forward or backward until the bottom center index line rests on the bottom of the target and the top center index line rests on the top of the target. The approximate range is displayed on the CITV display.
Figure 7-1. CITV Stadia Reticle.
GUNNER’S AUXILIARY SIGHT STADIA RETICLE
On the M1, M1A1, and M1A2, the stadia reticle pattern is included on both gunner’s auxiliary sight reticles.
If the laser range finder is inoperative, the stadia reticle may be used to determine the range to a target. The pattern has a base line and a series of range lines for full-height targets, and a series of dots for ranging at a target in hull defilade (see Figure 7-2). The GAS stadia reticle is designed to permit gunners to determine range to the target if other, more precise, ranging methods are not available. The full-size portion of the reticle is designed for a 2.30-meter-high target, while the turret portion is for a 0.90-meter-high target (see Figure 7-3).
With practice, gunners using the stadia reticle can consistently determine the range to within 100 meters.
Figure 7-2. GAS Stadia Reticle.
Full-Height Target.
Target in Hull Defilade.
Figure 7-3. GAS Stadia Reticle, Displaying Target.
RETICLE RELATIONSHIP METHOD
This method is a combination of the range estimation and engagement technique. It provides the TC a rapid, accurate alternate method of determining range to a target and successfully engaging the target. The reticle relationship method is based on an average enemy tank with the following dimensions:
• Width 3.4 meters.
• Height 2.3 meters.
• Length 6.7 meters.
When the reticle of either the GPS or GAS is superimposed over the enemy tank, the properly trained gunner or TC can rapidly determine if the target is within a preselected battlesight range, or if further range determination is required.
Gunners should also be trained to use the SABOT/STAFF and MPAT/HEAT reticles on the M1A1 and M1A2 GAS, and the SABOT and HEAT reticles on the M1 GAS to determine range. Since there is no vertical mil value established for these reticles, using a vertical measurement is not recommended.
ESTIMATED-RANGE METHOD
To engage targets when the LRF cannot be used and the range is unknown, the TC or gunner must estimate the range to the target. Range data is announced in the fire command in even hundreds or thousands, otherwise
• “INDEX ONE EIGHT HUNDRED,” the gunner uses the GPS and enters the range into the FCS using the CCP or GCDP.
• “GUNNERSABOTTANKCHOKE (description),” the gunner shifts to the GAS, selects the appropriate reticle, and uses the choke sight to estimate the range, then repeats the range to the TC.
GPS GAS
Range Announced As Announced As
900 meters "INDEX NINE HUNDRED" "NINE HUNDRED"
2,000 meters "INDEX TWO THOUSAND" "TWO THOUSAND"
1,200 meters "INDEX ONE TWO HUNDRED" "ONE TWO HUNDRED"
860 meters "INDEX NINE HUNDRED" "NINE HUNDRED"
3,040 meters "INDEX THREE THOUSAND" "THREE THOUSAND"
TANK COMMANDER'S MACHINE GUN METHOD
The TC's machine gun with sight reticle gradation can be used to determine range out to 1,800 meters. The TC's machine gun allows him to suppress the target and determine range at the same time. To aid the gunner in target identification and to reduce engagement time, the CWS should be aligned with the main gun. The disadvantage of this method is that the tank's position will be disclosed. (This method cannot be used on the M1A2.)
To use this method, the TC initiates the fire command (for example, "GUNNERHEAT ANTITANK,"
"CALIBER FIFTYRANGING”). The TC places his sight reticle aiming point on the target, and fires. He then observes the tracers and adjusts their impact until they strike the target. Once the tracers impact on, or near, the target, the TC reads the corresponding aiming point of the reticle and announces the range to the gunner, (for example, "ONE EIGHT HUNDRED" or "INDEX ONE EIGHT HUNDRED") followed by the execution element ("FIRE").
Note. If the tank is in a turret-down defensive position, it should move to a hull-down position; the commands "DRIVERMOVE OUT" and "DRIVERSTOP" must be issued before the execution command.
The TC's initial aiming point should correspond with the battlesight range for the ammunition announced in the fire command. By applying the battlesight range to the TC's sight, if the initial burst is observed over the target, the TC can engage immediately by announcing the battlesight range.