In some towhook systems, the high pressure loading on the  towhook causes towhook seizure, and the tow pilot may  not be able to release the towline from the towplane. This  situation can be critical if it occurs at altitudes below 500 feet  above ground level (AGL). Upon losing sight of the towplane,  the glider pilot must release immediately. The unassisted takeoff is basically conducted in the same  manner as a normal takeoff, but the glider is positioned slightly  off the runway heading (runway centerline) by approximately  10–20° with one wing on the ground. If the glider is canted to  the right, then the right wing would be resting on the ground.  To the left, the left wing would be resting on the ground.  When the glider pilot is ready for takeoff, he or she advises  the tow pilot either by radio, which is the preferred method, or  by signaling the tow pilot with the “ready for takeoff” rudder  waggle signal, as in the assisted takeoff. As the towplane  accelerates, the wing on the ground (trailing wing) accelerates  at a slightly faster rate as it is pulled in a slight arc, allowing  that wing to rise quickly with little dragging. If the glider is aligned with the towplane during the takeoff, the  wing that is on the ground has a tendency to be dragged and a  ground loop may occur (or severe swerving). After the wings  are level, proceed as in the normal takeoff configuration. Crosswind takeoff procedures are a modification of the  normal takeoff procedure. The following are the main  differences in crosswind takeoffs: Prior to takeoff, the glider pilot should coordinate with the  launch crewmember to hold the upwind wing slightly low  during the initial takeoff roll. If a crosswind is indicated,  full aileron should be held into the wind as the takeoff roll is  started. This control position should be maintained while the  glider is accelerating and until the ailerons become effective  for maneuvering the glider about its longitudinal (roll) axis.  With the aileron held into the wind, the takeoff path must  be held straight with the rudder. This requires application  of downwind rudder pressure, since the glider tends to  weathervane into the wind while on the ground.  [Figure 7-4] As the glider’s forward speed increases, the crosswind  becomes more of a relative headwind; the mechanical  application of full aileron into the wind should be reduced. It  is when increasing pressure is being felt on the aileron control  that the ailerons are becoming more effective. Because the  crosswind component effect does not completely dissipate,  some aileron pressure must be maintained throughout the  takeoff roll to prevent the crosswind from raising the upwind  wing. If the upwind wing rises, exposing more wing surface to  the crosswind, a skipping action may result, as indicated by a  series of small bounces occurring when the glider attempts to  fly and then settles back onto the runway. This side skipping  imposes side loads on the landing gear. Keeping the upwind  wingtip slightly lower than the downwind wingtip prevents  the crosswind from getting underneath the upwind wing and  lifting it. If the downwind wingtip touches the ground, the  resulting friction may cause the glider to yaw in the direction  of the dragging wingtip. This yaw could lead to a loss of  directional control and runway departure. While on the runway throughout the takeoff, the glider pilot  uses the rudder to maintain directional control and alignment  behind the towing aircraft. Yawing back and forth behind the  towplane should be avoided, as this affects the ability of the  towplane pilot to maintain control. If glider controllability  becomes a problem, the glider pilot must release and stop  the glider on the remaining runway. Remember, as the glider  slows, the crosswind may cause it to weathervane into the wind. 7-5 Unassisted Takeoff Crosswind Takeoff Assisted •  The glider tends to weathervane into the wind any time  the main wheel is touching the ground. The stronger  the crosswind is, the greater the tendency of the glider  is to turn into the wind. •  After lift-off, the glider tends to drift downwind off the  runway centerline. The stronger the crosswind is, the  greater the tendency of the glider is to drift downwind. Figure 7-4.  Crosswind correction for takeoff. Full downwind rudder deflection to start crosswind takeoff roll WIND WIND Upwind wing slightly lower than downwind wing