TM-9-2350-311-10 M109 Operator's Manual for M109A2, M109A3, M109A4 and M109A5 Download
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TM 9-2350-311-10 2–12 PREPARATION FOR FIRING — CONTINUED 2-12.7 Direct Fire Procedures — Continued c. Two Man/One Sight System The primary means of direct fire will be the two man/two sight method, The two man/one sight or one man/one sight system should only be used when the target and the howitzer are at the same elevation with no mask (site to crest) obstacles in between. Firing at targets above or below the howitzer position requires adjustments to the quadrants listed on the range chart. Adjustments must be computed by the Fire Direction Center (FDC) in accordance with FM 6-40. 1 Duties of chief of section are the same as for two man/two sight system, except that when giving fire command, chief of section announces quadrant instead of range. The DIRECT FIRE RANGE PLATE (12) located on the operating cam has all the information on direct fire. 2 The duties of gunner are same as for two man/two sight system. 2-228