"Purpose and Scope - This manual is published for the information and guidance of the civilian Ground Observers in the Air Defense System. It provides a complete description of their duties and responsibilities. Contents - The first part of this manual explains the operation of the Air Defense System and specifies the reporting procedures to be followed by Ground Observers. The second part of this manual includes the illustrations and other data required for aircraft identification."--Page i.

Merriam Press Military Reprint MR33 (First Edition, 2015). U.S. Army Air Forces World War II manual on how to identify aircraft. Aircraft identification of type and model is important for service personnel to assess threat posed by aircraft and to recognize "friendly" aircraft. Contents: The AAF Ground Observer Corps; Aircraft Identification (Wings; Engines; Fuselage; Tail); Use of the Manual; Silhouettes and Photographs (Bombers; Fighters; Observation and Liaison; Trainers; Transports; Seaplanes). Originally published in 1942 by the USGPO.