Spoilers retract after landing when which precise condition is met?

• A. Weight on Wheels is detected and wheel speed remains below 45 knots for 10 seconds
• B. 40 seconds after Weight on Wheels
• C. Wheel speed below 45 knots for 10 seconds only
• D. Immediately upon touchdown

Answer: (A)

Spoilers are used to dump lift and help control the airplane during and just after touchdown, but they don’t stay out forever. The system waits for confirmation that the airplane is truly on the ground and not still moving or bouncing. The key signal is Weight on Wheels, which proves the aircraft is in contact with the runway. But that alone isn’t enough—the wheels also need to be turning slowly, indicating the airplane is decelerating on the ground rather than still airborne or bouncing. The requirement that wheel speed stay below 45 knots for a continuous 10 seconds provides this confirmation.

Once both conditions are met, the spoilers can retract safely because lift is no longer needed for deceleration or stability on the ground, and retracting too early could cause unwanted lift or control issues if the airplane isn’t settled. If either condition isn’t satisfied, the spoilers stay extended to continue providing lift dump and pitch/roll stability during the rollout.

The other options don’t fit because they either miss the need for a confirmed on-ground state (Weight on Wheels) or skip the necessary time and speed stability checks, or they imply an immediate retraction that could occur during the flare or early contact, which isn’t how the system ensures safe and stable post-landing behavior.