What is necessary for a pre-takeoff contamination check during icing conditions?

For a pre-takeoff contamination check during icing conditions, it is essential to complete the check within a specific timeframe to ensure safety and compliance with regulations. Conducting this check within the last 5 minutes before takeoff is crucial because it ensures that any ice or snow that may have accumulated on the aircraft's critical surfaces due to recent weather conditions does not affect the aircraft's performance or handling characteristics.

A timely inspection helps verify that the aircraft is free of contaminants that could hinder safe operation, as ice or snow can change the aerodynamic properties and increase the risk of accidents during takeoff and initial climb. This requirement aligns with standard operating procedures for aircraft in icing conditions, emphasizing the importance of prompt checks to maintain safety standards.

The other options, while related to de-icing and inspections, do not fulfill the specific requirement that emphasizes the critical time factor for completing a contamination check just before takeoff.