Ground Track GLYPH<127> Flightpath Heading Wind $_{ Co}$rrection  Angle (Cr a b Angle) Wind 25 TAKEOFF ROLL ROTATION—LIFT-OFF CLIMB Wind Figure 7-8. Crosswind takeoff. Figure 7-7. Wing correction angle (or crab angle as is is commonly  called). the climb technique is the same used for normal takeoffs and  climbs maintaining the proper ground track with the proper  wing correction angle/crab angle.  [Figure 7-8]  In addition to normal takeoffs, additional common errors in  the performance of crosswind takeoffs are: Ground effect is a condition of improved performance  encountered when the aircraft is operating very close to  the ground. Ground effect can be detected and measured  up to an altitude of about one wingspan above the surface.  [Figure 7-9]  However, ground effect is most signifi cant when  the WSC aircraft is maintaining a constant attitude at low  airspeed and low altitude. Examples are during takeoff when  the aircraft lifts off and accelerates to climb speed, and also  during the landing fl are before touchdown. When the wing  is under the infl uence of ground effect, there is a reduction  in upwash, downwash, and wingtip vortices. Since the WSC wing is a high wing aircraft, the effects  are not as pronounced as a low wing airplane, but during  rotation, the reduction in induced drag is about 25 percent  and decreases as the WSC aircraft climbs. At high speeds  where parasite drag dominates, induced drag is a small part  of the total drag. Consequently, the effects of ground effect  are of greater concern during takeoff and landing.  Ground Effect on Takeoff 7-7 • Letting the windward side of the wing get too high. • Allowing the wing to weathervane into the wind  during the takeoff roll. • Not obtaining additional speed before rotation. • Too slow of a rotation during lift-off.  • Inadequate drift correction after lift-off.