Performing Aircraft Slips
Forward slips and side slips are relatively easy maneuvers to practice and learn. They may feel uncomfortable at first, but after some getting used to them with your instructor and practicing at a safe high altitude, you’ll become familiar and comfortable with what the proper control inputs are and just exactly how aggressive you can be with them!
An easy way to remember the difference between the two slips is:
- Side Slips are used for slipping sideways through the air during a crosswind landing
- Forward Slips are used to lose altitude quickly and take you forward towards the runway (presumably, or whatever else you are trying to lose altitude to get down to).
Forward slips and side slips have a lot in common. They both:
- Are cross controlled maneuvers
- Need to be accomplished with adequate airspeed and caution used NOT to exceed critical AOA and stall
- Cause more parasitic drag to be felt by the airplane
- Will cause an increased rate of loss of altitude, unless you add power
- Make your passengers and you feel a little funny (as your passengers and their stomachs get the feeling of being pushed to the side)
- Should be practiced first at high and safe altitudes
- Should be entered slowly
- Are essential maneuvers for pilots to understand and master regardless of what aircraft you are flying
Aerodynamic Impact of Slips
When you enter a forward slip in an effort to lose altitude more rapidly, the airflow around the aircraft changes rapidly.
- The wings will no longer be level, therefore reducing the total amount of lift they can produce at any given airspeed.
- Dependent on the direction of the slip, a substantial amount of additional drag will be created by the airflow hitting the left or right side of the airplane.
- In a slip, the rate of descent is primarily controlled by the angle of bank. Available rudder authority will determine how effective or aggressive your slip can become.
- Your airspeed indicator will not be accurate in a slip as the air inlet for the airspeed indicator is not in line with the wind. Never completely rely on your airspeed indicator in a slip!
- Do not continually reduce airspeed in an attempt to lose altitude more quickly, as this may result in a cross-controlled stall. Instead, if you find yourself needing to increase the rate of descent, lower the nose. This will increase both the rate of descent and airspeed. As airspeed increases, more rudder authority will become available, allowing you to increase bank.
- When using a forward slip to lose altitude, always take the airplane out of the slip and reduce the rate of descent before touchdown! Touching down at a high rate of descent, in a cross-controlled condition, is going to be a bad day!
- Before performing slips to lose altitude on final, practice them at a high, safe altitude with your instructor. Use those rudder pedals and feel the airplane!