A Course for Ground Engineers: IX.—Hints on the Care and Inspection of Instruments for Applicants for “A,” “B,” “C,” and “X” Licences Available to Purchase

TURN INDICATORS TURN indicators are primarily used to indicate deviations from a straight course. When flying in fog, it is practically impossible to keep to the course by the compass alone, and the turn indicator is of service in enabling the pilot to preserve a straight course without reference to landmarks on the ground. The instrument also gives important information as to whether the aircraft is correctly banked on a turn, as described in the section headed “Cross Level” above.