What is the required time window for performing a pre-takeoff contamination check?

• A. Within 1 minute of takeoff
• B. Within 15 minutes of takeoff
• C. Within 30 minutes of takeoff
• D. Within 5 minutes of takeoff

Answer: (D)

Contamination checks are done after de-icing/anti-icing to confirm that frost, ice, or snow is not on the aircraft’s critical surfaces. The timing matters because conditions can change quickly and the effectiveness of de-icing can diminish, so you want to verify the surface condition as close to takeoff as practical.

The required window is the last five minutes before takeoff. This maximum window ensures the observed condition reflects what will exist at liftoff, reducing the chance that new contamination could form or accumulate after the check. Windows longer than five minutes wouldn’t guarantee a current condition, and while a check done very close to takeoff is fine, the regulation specifies five minutes as the established window.