PLT244: Stability and Controllability
What code PLT244 covers, why the FAA tests it, and how to study Stability and Controllability before your checkride.
Recall forces acting on aircraft - stability / controllability
What this means for your checkride
Stability is the airplane's tendency to return to steady flight on its own. Static stability is the initial response to a disturbance; dynamic stability is what happens over time, whether the oscillations damp out or build up. Controllability is the pilot's ability to maneuver against that stability.
Stability and controllability are a design trade-off that affects how the airplane handles, so the FAA tests the difference between static and dynamic stability and how center of gravity position shifts both.
Pilots think more stability is always better. A very stable airplane is harder to maneuver, and an aft center of gravity reduces stability, which can make an airplane dangerously difficult to recover from a stall.
Where to study it
Oral checkride defense
A code on your report is an area the examiner can revisit. Here is how an examiner might probe it, and how to explain it out loud.
Explain static versus dynamic stability.
Static stability is the airplane's initial tendency to return toward equilibrium after a disturbance. Dynamic stability is what the resulting oscillations do over time, damping out, holding steady, or growing. A good-handling airplane is positive in both.
How does an aft CG affect stability?
Moving the CG aft reduces longitudinal stability and elevator effectiveness. The airplane becomes less stable in pitch and harder to recover from a stall, which is why staying within the aft CG limit matters as much as gross weight.
A code on your test report is an area of deficiency. An authorized instructor must review it with you and endorse that review before you take the practical test, and the examiner may revisit it during the oral. Study it until you can explain it out loud, not just recognize the answer.