Protection of German cities and strategic centers against night raids
depends in part on huge concentrations of searchlights. Once a raider is picked
up, sharp needles of light focus their points in a blinding cone of billions of
candle power. A single light can often be shaken off with comparative ease. It
is extremely difficult to escape from the effect of 20 or 30 lights pointing up at
the same time.
The terms "dazzle" and "glare" are often confused with One another.
Dazzle is the direct blinding effect of the powerful rays on pilot and bombardier,
glare is the light interposed between observer and target in such a way that the
target is obscured.
The success of dazzle clearly depends on the height of the aircraft, conditions
of atmosphere, and positions of searchlights relative to the aircraft's
course, and probably to some extent on individual reactions.
The following are some inferences drawn from recent trials:
a. Dazzle does not occur unless the aircraft is directly illuminated
by one or more beams.
b. A single beam will not produce the effect except at fairly short range.
c. A concentration of several beams can cause acute difficulty to
pilot or bombardier.
d. Head-on illumination causes far more difficulty to aircraft than
does illumination from abeam or astern.
e. Short-range engagement of enemy aircraft by searchlights has
apparently caused pilots to lose control and crash, but this inference is difficult
The dazzle or glare effect is most pronounced between 2,000 and 4,000
feet, and is effective up to 15,000 feet. Dazzle effect of British searchlights has
in several cases brought down British fighters and bombers. British pilots
report that dazzle or glare at altitudes even exceeding 10,000 feet (as used by the
Germans) blinds pilots, makes location of target and accuracy of bombing difficult,
impairs night adaptation of eyes, and has a pronounced psychological
effect. It is most disconcerting to pilots and gunners to be thus illuminated, and
rendered unable to see a fighter plane approaching to attack. The glare effect
of a searchlight trained upon a low-flying aircraft is so great that it makes
low-flying attacks hazardous. The glare effect of antiaircraft searchlight beams
does not interfere materially with crews of aircraft not directly in the beam; it
is therefore important to keep the beams constantly on the enemy aircraft, giving
defending fighters full opportunity to attack.
The Germans are reported to indicate to their fighters the course of an
enemy aircraft by dipping the beam of a searchlight, or by controlled travel
across the sky of the intersection of searchlight beams.