(aerial; ground; supplement) (2-9)
Engineer reconnaissance can be performed by ______________________ and ________________________, by
_____________________________ observers, or by ______________________ parties, either independently, or in
(measurement; distortions) (2-33)
Aerial photography, while a valuable _____________________________________ to map study, should not be
relied upon exclusively for reconnaissance because detail may be ________________________________ or aircraft
grounded. Because of scale and image distortions, _____________________________________ may be unreliable.