In order to assist in estimating the chances of being successfully engaged by antiaircraft
fire when operating over enemy territory, three diagrams are here shown. They illustrate
the ceilings of light and heavy antiaircraft guns and the zones of engagement of heavy
a. Ceilings of Heavy AA Guns
The chance of being hit at the maximum ceiling (shown in figure 1 by broken-line
trajectories), although it cannot be ruled out, is extremely small owing to the very long
time of flight of the projectile and the fact that only one round can reach these heights
while the plane is within range.
Prolonged engagements of a plane or formation are possible only at lower heights. The effective
ceiling (shown in figure 1 by solid lines) for the 88-mm and 105-mm guns
represents the maximum height at which a directly approaching aircraft flying at 300 mph
can be engaged for 20 seconds with the last round fired at a quadrant elevation
of 70 degrees. It will be seen that the resultant effective ceiling for
the 88-mm gun, for example, is 26,250 feet. The accuracy of this basis
of calculation is borne out by recently received evidence which suggests that the "88" does
in fact have great difficulty in effectively engaging targets flying at about 26,000 feet.
Fire at the effective ceiling is apt to be only relatively accurate, although a number of
reports have come in of accurate barrage fire at considerable heights. In these cases,
however, formations had flown a constant course and height for unduly long periods, and
this allowed ample time for the preparation of firing data. Aside from special situations
of this kind, the most effective heights for fire by heavy guns on targets in sight are
between 4,000 and 10,000 feet for individual aircraft, and between 4,000 and 14,000 feet
against formations. For unseen targets, the most effective height is from 6,000 to 12,000 feet.
The lethal radii of burst noted in figure 1 are necessarily approximate. It should be
remembered that the major effect of a burst is forward, so that danger from a
close burst above an airplane is considerably less than a burst in any other position.
b. Ceilings of Light AA Guns
Figure 2 is largely self-explanatory.* The sights used with light AA guns are chiefly of
value for obtaining accurate opening fire. Subsequently, corrections are generally made
by observation of tracer. This fact; together with the falling away of the trajectory
above certain heights, mainly accounts for the distinction between heights to which
accurate engagement is considered likely and heights at which self-destruction takes
place. It will be obvious that this distinction shown by the change from solid to dotted
trajectories in figure 2 is very approximate.
c. Zones of Engagement of 88- and 105-mm Guns
Figure 3 is a diagram designed as a guide for estimating how closely aircraft flying at
various heights can approach a gun position without being engaged. This diagram shows the
maximum ranges and dead zones of 88-mm (solid line) and 105-mm (broken
line) antiaircraft guns from which can be read off maximum zones of engagement. These zones
apply to directly approaching targets. For any other target course, zones of engagement
will be smaller. The 150-mm gun (not included owing to insufficient data) is
known to have better performance, and some additional allowance should therefore be made
for this weapon.
The 88-mm and 105-mm guns constitute the main German heavy antiaircraft equipment. The
existence of a 150-mm AA gun is supported by only scanty
evidence. The 128-mm AA gun is believed to be in use and to have a
ceiling of from 35,000 to 40,000 feet.
*It should be noted that the rate of fire indicated in figure 2 for the 20-mm gun
has reference to the single-barreled gun; the four-barreled 20-mm AA gun fires
about 700 to 800 rounds per minute.