As the maneuver continues, the pilot reduces the rudder  pressure and uses coordinated flight controls to slightly bank  the glider to fly along the top side of the box. The glider  proceeds to the opposite corner using aileron and rudder  pressure, as appropriate. The pilot maintains this position  momentarily with rudder pressure, then begins a vertical  descent by applying forward pressure to the control stick.  Rudder pressure is used to maintain glider position at an  equal distance from the wake. The pilot holds the wings level with the ailerons to parallel the  towplane. When the glider has attained low corner position,  the pilot momentarily maintains this position. The pilot  releases the rudder pressure and, using coordinated flight  controls, slightly banks the glider to fly along the bottom side  of the box until reaching the original center low tow position. From center low tow position, the pilot maneuvers the glider  through the wake to the center high tow position, completing  the maneuver. Common errors when boxing the wake include: Prelaunch visual signals for a ground launch operation allow  the glider pilot, the wing runner, the safety officer, and the  A CG hook, as compared to a nose hook, makes a crosswind  takeoff more difficult since the glider can weathervane into  the wind more easily. In addition, a CG hook makes the glider  more susceptible to kiting on takeoff, especially if the CG  is near the aft limit. This can present a serious danger to the  towplane during the aerotow. If the CG hook is in the landing gear well, retracting the gear  on tow interferes with the towline. Even if the glider has a  nose hook, retracting the gear on tow is not recommended until  the aircraft is safely airborne and an immediate or emergency  return is not necessary. Leaving the gear down allows the  glider pilot more time to assess the best landing options. Some training and high-performance gliders have only  a CG towhook. CG towhooks are necessary for ground  launch operations so the glider is not pulled into the ground.  Attachment at the center of gravity allows the glider pilot to  have full control of the glider without undue influence from  the ground pull. Attachment of a ground launch towline to  the nose hook would tend to pull the glider into the ground  and would overload the horizontal stabilizer and elevator.  Conversely, depending on design, the CG hook may not  have sufficient movement to fully release an aerotow line  under pressure. If the hook only swings about 90° down, the  towline may stay hung on the gliders hook until the pressure  is released and slack allows the towline to simply fall off. It  may be located either ahead of the landing gear, in the landing  gear well, or the glider may utilize a bracket that attaches  outside on the fuselage near the cockpit. feature of the towhook is so important, it should be tested  prior to every flight.  [Figure 7-13] •  Performing an excessively large rectangle around the  wake.  Figure 7-12  has exaggerated positions and is  not to scale. •  Improper control coordination and procedure. •  Abrupt or rapid changes of position. • Allowing or developing unnecessary slack during  position changes. Ground Launch Takeoff Procedures Signals Prelaunch Signals (Winch/Automobile) When ground launching, it is essential to use a center of  gravity (CG) towhook that has an automatic back release  feature. This protects the glider if the pilot is unable to release  the towline during the launch. The failure of the tow release  could cause the glider to be pulled to the ground as it flies  over the launching vehicle or winch. Since the back release  Automatic back release— check before every launch. Tow ring Figure 7-13.  Testing the towhook. 7-11 CG Hooks