During climbs and descents in flight conditions which permit visual detection of other traffic, pilots can execute gentle banks left and right at a frequency which permits continuous visual scanning of the airspace. Throughout sustained periods of straight and-level flight, executing appropriate clearing procedures at periodic intervals can help clearing the vicinity. During instruction, the pilot should be asked to verbalize the clearing procedures (call out "clear left, right, above, and below").
AIM 4-4-15 Use of Visual Clearing Procedures
PHAK Ch-14 (28) Clearing Procedures
AFH Ch-01 (12)
Cessna SOPM 2-28 Clearing Turns