The COMPASS March Issue | Page 16

too fast , you will find your airplane “ floating ” as you flare , and you could use up a lot of extra runway .
If you find yourself high on final or need to fly a steeper approach to clear obstacles without flaps you can use a forward slip to steepen your descent . A forward slip is a way of creating extra drag in the absence of flaps as a means of achieving a steeper descent . Forward slips are done with the power at idle . The purpose of the slip is to increase the rate of descent ; therefore , to have power applied at the same time would be counterproductive . A forward slip is a descent with one wing lowered using aileron and the longitudinal axis of the airplane yawed at an angle to the flight path using opposite rudder . To initiate a forward slip on final approach , lower one wing using aileron and yaw the longitudinal axis of the airplane in the opposite direction using rudder . If there is crosswind , lower the wing on the side from which the wind is coming . Yaw the nose in the opposite direction to the bank just enough to maintain the desired ground track .
Because the pitot tube and static ports will not be correctly aligned with the airflow during the slip , you cannot depend on accurate airspeed indications in this configuration . So , be particularly attentive to other indications of getting too slow , such as mushy controls or buffeting . If you get too close to a potential stall speed , lower the nose to increase airspeed and reduce the angle of attack .
Prior to touchdown , it will be necessary to realign the longitudinal axis of the airplane with the runaway centerine . To straighten out prior to flaring , level the wings and release rudder pressure simultaneously to align the longitudinal axis of the airplane with the centerine and then flare to touch down as normal .
Slips are also used in crosswind landings , in which cases a sideslip can be used to create a sideways force that is equal to and opposite to the force of the wind drift .
To land when the wind is not aligned with the runway requires a technique for overcoming the sideways drift that the wind tends to induce . On final approach , this wind drift can be counteracted by either a crab or sideslip . A crab simply entails selecting a heading towards the direction the wind is coming from while flying wings level . The Wind Correction Angle selected should be enough to prevent drift and maintain a straight ground track along the extended centerline . Adjust the Wind Correction Angle as necessary to achieve zero drift . If you fly your final approach with a crab , it will be necessary to align the longitudinal axis of the airplane with the runway prior to touchdown . This alignment needs to be made just prior to touchdown . It requires precise timing to avoid drifting if the crab is terminated too soon or landing out of alignment with the center line if you leave it too late . The landing gear is not designed to handle side loads , so it is very important that the airplane be longitudinally aligned with the centerline and not drifting on touchdown .
The alternative to the crabbed approach and last minute correction is to use a sideslip to counteract wind drift . This can be done for the whole final approach or just for the last part after starting out using a crab . The idea is to lower the wing on the side from which the wind is coming , using aileron to counteract wind drift , and to use opposite rudder to maintain longitudinal alignment with the centerline . The extent to which the wing is lowered will depend on the force of the wind . If you get to the point where to counteract wind drift you need to lower the upwind wing so much that full opposite rudder is insufficient to maintain