If stabilizer ice is suspected and the anti-ice/deice switches are off, what is the recommended flap limit?

• A. 0 degrees
• B. 5 degrees
• C. 10 degrees
• D. 15 degrees

Answer: (C)

Stabilizer icing raises the risk of tailplane stall and loss of pitch control, especially when anti-ice is not protecting the stabilizer. Keeping flap extension modest helps prevent extra tailplane loading that could cause ice to shed abruptly and degrade control effectiveness. With anti-ice/deice switches off, the safest, officially recommended limit is to use no more than 10 degrees of flaps.

Zero degrees would keep tailplane loading very low but isn’t practical for a normal approach/landing configuration. A smaller setting like 5 degrees provides less load but isn’t the advised maximum under these icing conditions. Extending to 15 degrees would increase tailplane loading and the potential for ice-related issues, making control more troublesome.