Which factor directly affects the minimum control speed on the ground (VMCG)?

• A. Landing gear contact with the runway
• B. Engine thrust
• C. Wing sweep
• D. Flap setting

Answer: (A)

VMCG is the speed at which you can keep the airplane under control on the ground when one engine is inoperative. The key thing that makes this possible is the tire-ground friction provided by the landing gear contact with the runway. When all the wheels are on the surface, the tires generate lateral resistance that helps counteract the yaw from thrust asymmetry, allowing you to hold the centerline with rudder and braking even at lower speeds. If the aircraft isn’t yet fully on the runway, that friction is reduced or absent, making directional control harder and raising the speed you’d need to maintain control. The other factors—engine thrust, wing sweep, flap setting—affect the aerodynamic and thrust moments but don’t provide the essential ground friction that directly enables control on the runway, so they don’t determine VMCG in the same direct way.