A Pre-Takeoff Contamination Check must be conducted when which of the following conditions exist?

A Pre-Takeoff Contamination Check is crucial for ensuring the aircraft's safe operation, particularly in adverse weather conditions. When ground icing conditions exist, it is essential to conduct this check to verify that no ice, snow, or other contaminants have accumulated on critical surfaces such as wings, tail, and control surfaces. These contaminants can significantly impair the aircraft's aerodynamic performance, causing issues such as reduced lift and increased drag, potentially leading to hazardous flight situations.

Conducting the Pre-Takeoff Contamination Check in the presence of ground icing conditions aligns with best practices for safety and compliance with regulatory standards. This proactive step helps the crew confirm that the aircraft is in the best possible condition for takeoff, ensuring both safety for the flight and compliance with procedural guidelines.