When must a Pre-Takeoff Contamination Check be completed?

The completion of a Pre-Takeoff Contamination Check is crucial for ensuring that the aircraft is safe for takeoff, particularly in cold weather conditions where ice, snow, or other contaminants may affect aircraft performance and safety. The requirement to perform this check within 5 minutes prior to takeoff ensures that the aircraft is evaluated for contamination when it's most relevant—right before it is about to take off.

This timing aligns with the dynamic nature of weather and conditions that can change rapidly, allowing crews to make informed decisions based on the most current state of the aircraft's surfaces. By conducting the check so close to takeoff, crews can ensure that any contaminants that may have formed since the last inspection, possibly due to changing conditions or delays, are identified and addressed immediately.

Timing is critical, and the designated window allows for an accurate assessment of the aircraft's state, thus minimizing the risk of takeoff under unsafe conditions.