Wing anti-ice valves close after how many minutes if the ice detector does not detect ice?

• A. 3 minutes
• B. 1 minute
• C. 5 minutes
• D. 10 minutes

Answer: (A)

When the ice detector does not sense ice, the wing anti-ice valves shut off after a short automatic time-out to conserve bleed air and avoid running anti-ice needlessly. This time-out is three minutes in this case, which balances the risk of ice formation against wasting bleed air when there’s no ice present. If ice is detected, the valves stay open to protect the wings; the time-out only applies when no ice is detected. The other intervals would either let anti-ice remain on too long without ice or shut it off too quickly, risking ice buildup if conditions change.