What Is Side-Slipping?

Early aircraft types, and many modern light aircraft, have no flaps. This leaves the pilot with the dilemma of increasing the glide angle, inducing excessive airspeed which has to be bled-off when the aircraft levels out (e.g. in the flare for landing). The solution is a much neglected maneuver known as the sideslip.

Side-slipping basically amounts to flying sideways. In a descent it implies deliberately flying the aircraft grossly out of balance, usually by applying bank in one direction then using opposite or ‘top’ rudder so that the aircraft descends in a straight line. The extra drag caused by flying the aircraft out-of-balance worsens the L/D ratio so the glide angle will become steeper without the airspeed increasing. Side-slipping is a simple maneuver well worth the exercise, bearing the following in mind:

• Check the aircraft’s POH/FM to ensure that side-slipping, particularly with flaps lowered, is permitted.

• If fuel levels are low, an excessive slip or skid could uncover the inlet pipe in a fuel tank, leaving the engine without fuel.

• Avoid steep angles of bank and excessive slipping, which will lead to very high rates of descent. Upon recovery to balanced flight, the energy of the aircraft in a steep descent may translate into extra airspeed.

• Unbalanced flight can cause significant errors in the airspeed indicator (ASI) reading. It is normally necessary to pitch down in a sideslip to maintain a safe airspeed.