TM-9-2350-311-10
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; OPERATOR’S MANUAL
NOVEMBER 1994
TM-9-2350-311-10 - Page 316 of 775
TM 9--2350--311--10
2--218
Change 6
2--12 PREPARATION FOR FIRING — CONTINUED
2--12.6
Laying For Direction and Quadrant During Indirect Fire Mission — Continued
b. Laying for Direction Using M1A2 Aiming Posts
NOTE
During rapid traverse operations, or if the gunner informs the section chief that the M1A1/M1A2
collimator isn’t working, an alternate aiming point may be used. If the M1A2 aiming posts are
used as primary aiming point, omit steps 1 and 2 below.
1
Gunner opens access door (11) that covers M117/M117A2 panoramic telescope (1) azimuth counter
(12). Gunner rotates azimuth knob (2) until azimuth, on which M1A2 aiming posts (13) were originally
emplaced, appears on azimuth counter. Gunner rotates and centers panoramic telescope ballistic cover
(not shown) on M117/M117A2 panoramic telescope line of sight.
2
Gunner rotates reset knob (14) until 3200 appears on reset counter (3). The section chief verifies the
aiming post deflection on true azimuth scale before the gunner closes access door (11), covering
azimuth counter (12).
3
Upon announcement or data display of “DEFLECTION (SO MUCH),” gunner rotates azimuth knob (2)
until announced deflection appears on reset counter (3). Gunner then reads setting to chief of section.
4
Sighting through M117/M117A2 panoramic telescope (1), gunner operates traverse control handle until
a proper sight picture on M1A2 aiming posts (13) appears. If there is no weapon displacement, gunner’s
sight picture on M1A2 aiming posts should appear as shown.
5
To correct for weapon displacement, gunner must compensate so that far M1A2 aiming post (13)
appears exactly halfway between near M1A2 aiming post and M117/M117A2 panoramic telescope (1)
vertical hairline. If the gunner sees near M1A2 aiming post to right of far M1A2 aiming post, weapon has
experienced left displacement. To compensate, gunner traverses weapon until far M1A2 aiming post is
exactly halfway between near M1A2 aiming post and M117/M117A2 panoramic telescope vertical
hairlines, as shown.
6
If gunner sees that near M1A2 aiming post (13) is to left of far M1A2 aiming post, weapon has
experienced right displacement. To compensate, gunner traverses weapon until far M1A2 aiming post is
exactly halfway between near M1A2 aiming post and M117/M117A2 panoramic telescope (1) vertical
hairlines as shown.
7
After assistant gunner lays cannon for elevation and announces “SET,” gunner verifies that announced
deflection appears on reset counter (3), pitch level (5) and cross-level (6) bubbles are centered, and
proper sight picture is obtained on M1A2 aiming posts (13). Gunner announces, “READY.”
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