clearing turns looking to the left and the right, as well as  above and below the airplane. The maneuver area should  not cause disturbances and be well away from groups of  people, livestock, or communities. Before performing any  maneuver, the pilot should complete the required checklist  items, make any radio announcements (such as on a practice  area frequency), and safety clearing turns. As a general note,  a ground reference maneuver should not exceed a bank angle  of 45° or an airspeed greater than maneuvering speed. As  part of preflight planning, the pilot should determine the  predicted (POH/AFM) stall speed at 50° or the highest bank  angle planned plus some margin for error in maneuvering When flying straight and level and following a selected  straight-line direct ground track, the preferred method of  correcting for wind drift is to angle the airplane sufficiently  into the wind to cancel the effect of the sideways drift caused  by the wind. The wind’s speed, the angle between the wind  direction and the airplane’s longitudinal axis, and the airspeed  of the airplane determines the required wind correction angle.  For example, an airplane with an airspeed of 100 knots, a 20  knot wind at 90° to the airplane’s longitudinal axis, and a 12°  angle into the wind is required to cancel the airplane’s drift.  If the wind in the above example is only 10 knots, the wind  correction angle required to cancel the drift is six degrees.  When the drift has been neutralized by heading the airplane into  the wind, the airplane will fly the direct straight ground track. Wind direction and velocity variations are the primary  effects requiring corrections of the flightpath during ground  reference maneuvers. Unlike an automobile, but similar to a  boat or ship, wind directly influences the path that the airplane  travels in reference to the ground. Whenever the airplane is  in flight, the movement of the air directly affects the actual  ground track of the airplane.  To further illustrate this point, if a boat is crossing a river  and the river’s current is completely still, the boat could head  directly to a point on the opposite shore on a straight course  to that opposite point without any drift; however, rivers tend  to have a downstream current that must be considered if the  captain wants the boat to arrive at the opposite shore using  a direct straight path. Any downstream current pushes the  boat sideways and downstream at the speed of the current.  To counteract this downstream movement, the boat must  move upstream at the same speed as the river is moving the  boat downstream. This is accomplished by angling the boat  upstream sufficiently to counteract the downstream flow. If  this is done, the boat follows a direct straight track across  the river to the intended destination point. The amount of  angle required is dependent on the forward speed of the boat  and the speed of the current. The slower the forward speed  of the boat and/or the faster speed of the current, the greater  the angle must be to counteract the drift. The converse is  also true.  [Figure 6-1] For example, an airplane is traveling at 90 knots (90 nautical  miles per hour) and the wind is blowing from right to left at  10 knots. The airplane continues forward at 90 knots but also  travels left 10 nautical miles for every hour of flight time. If  the airplane, in this example doubles its speed to 180 knots,  it still drifts laterally to the left 10 nautical miles every hour.  The airplane travels within an often moving body of air, so  traveling to a point on the surface requires compensation for  the movement of the air mass.  Ground reference maneuvers are generally flown at altitudes  between 600 and 1,000 feet above ground level (AGL).  The pilot must consider the following when selecting the  maneuvering altitude: As soon as an airplane lifts off the surface and levels the  wings, if there is any crosswind, the airplane will begin  tracking sideways with the wind. Any wind not directly on  the nose or tail of the airplane will drift the airplane sideways  at a speed up to the speed of the wind. A wind that is directly  to the right or the left (at a 90° angle) drifts the airplane  sideways at the speed of the wind; when the wind is halfway  between the side and the nose of the airplane (at a 45° angle),  it drifts the airplane sideways at just over 70 percent of the  speed of the wind. It should be understood that pilots do  not calculate the required drift correction angles for ground  reference maneuvers; they merely use the references and  adjust the airplane’s relationship to those references to cancel  any drift. The groundspeed of the airplane is also affected  6-3 • The lower the maneuvering altitude, the faster the  airplane appears to travel in relation to the ground. • Drift should be easily recognizable from both sides  of the airplane. • The altitude should provide obstruction clearance of  no less than 500 feet vertically above the obstruction  and 2,000 feet horizontally.  • In case of an engine failure, the pilot must plan,  consider, and be alert for forced landing areas while  understanding that the lower the airplane’s altitude,  the less time there is to configure the airplane for an  emergency landing and the shorter the glide distance.  • Any specific altitude required by test standards. Correcting Drift During Straight-and-Level Flight Drift and Ground Track Control