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to the glider pilot. However, the pilot still needs proficiency in performance of forward slips to correct for possible errors in judgment of the landing approach. 

The forward slip is a slip in which the glider’s direction of motion remains the same as before the slip was begun. If there is any crosswind, the slip is much more effective if made into the wind. If the glider is originally in straight flight, the wing on the side that the slip is to be made should be lowered by using the ailerons. Simultaneously, the glider’s nose must be yawed in the opposite direction by applying opposite rudder so the glider’s longitudinal axis is at an angle to its original flightpath. The degree to which the nose is yawed in the opposite direction from the bank should be such that the original ground track is maintained. The nose should also be raised as necessary to prevent the airspeed from increasing. 

The primary purpose of forward slips is to dissipate altitude without increasing the glider’s airspeed, particularly in gliders not equipped with flaps or those with inoperative spoilers/dive brakes. There are many circumstances requiring the use of forward slips, such as in a landing approach over obstacles and in making off-field landings. It is always wise to allow an extra margin of altitude for safety in the original estimate of the approach. In the latter case, if the inaccuracy of the approach is confirmed by excess altitude when nearing the boundary of the selected field, slipping may dissipate the excess altitude. 

The use of slips has definite limitations. Some pilots may try to lose altitude by violent slipping rather than by smoothly maneuvering, exercising good judgment, and using only a slight or moderate slip. In off-field landings, this erratic practice invariably leads to trouble since enough excess speed may result in preventing touchdown anywhere near the touchdown point, and very often results in overshooting the entire field. 

A sideslip, as distinguished from a forward slip, is one during which the glider’s longitudinal axis remains parallel to the original flightpath, but in which the flightpath changes direction according to the steepness of the bank. [Figure 7-28] The sideslip is important in counteracting wind drift during crosswind landings and is discussed in the crosswind landing section of this chapter. 

Sideslip is used during the last portion of a final approach. The longitudinal axis of the glider must be aligned with the runway just prior to touchdown so the glider touches down in the direction in which it is moving. This requires timely action to decrease the slip to maintain ground track alignment with the landing zone. Failure to accomplish this alignment imposes severe sideloads on the landing gear and imparts violent ground looping tendencies. 

Decreasing the slip is accomplished by leveling the wings and simultaneously releasing the rudder pressure while readjusting the pitch attitude to the normal glide attitude. If the pressure on the rudder is released abruptly, the nose swings too quickly into line and the glider tends to acquire excess airspeed. 

Because of the location of the pitot tube and static vents, airspeed indicators in some gliders may have considerable error when the glider is in a slip. The pilot must be aware of this possibility and recognize a properly performed slip by the attitude of the glider, the sound of the airflow, and the feel of the flight controls. 

Common errors when performing a slip include: 

• Improper glidepath control. 

• Improper use of slips. 

• Improper airspeed control. 

• Improper correction for crosswind. 

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