The Aviation Selection Test Battery, or ASTB, is used by the military branches to evaluate people for possible entrance into flight officer training programs. The military produces no official study guide, but numerous commercially available ASTB study guides can be purchased in bookstores or online.
The military suggests that people can only take the ASTB test three times in their lives, making adequate preparation vitally important in order to obtain a qualification score. The test is divided up into multiple subtests, most of which are aptitude tests. One section, the Aviation and Nautical Information subtest, is information-based, so study materials can be quite helpful for score improvement in this section.