If the ball in the slip/skid indicator is not centered, what does that indicate?

• A. The aircraft is not in coordinated flight.
• B. The aircraft is in coordinated flight.
• C. The bank angle is zero.
• D. The turn is perfectly coordinated.

Answer: (A)

When a turn is coordinated, the aircraft’s lateral forces are balanced and no side forces cause a slip or skid. The slip/skid indicator ball sits centered only in this balanced state. If the ball is off-center, it shows a sideslip or skid, meaning the aircraft is not in coordinated flight. The ball’s position tells you which way you’re slipping or skidding, so you know you need rudder or a different bank to bring it back to center. The other statements describe perfect coordination or zero bank, which would keep the ball centered, so they don’t fit when the ball is off-center.