Under what condition is it permissible to takeoff with regard to frost or ice on an aircraft?

Taking off with no frost, ice, or snow on critical surfaces is essential for maintaining control and performance during flight. Critical surfaces include the wings, control surfaces, and tail, as any contamination on these areas can significantly affect lift, airflow, and the aircraft's overall aerodynamics. Frost, ice, or snow can disrupt the smooth flow of air over the wings and lead to increased stall speeds, reduced lift, and potential handling issues. Therefore, a clean aircraft ensures safe operations and is a fundamental requirement before takeoff.

The presence of frost or ice, even on non-critical surfaces, could still pose hazards if it falls off during flight or affects the overall aerodynamic efficiency of the aircraft. Hence, ensuring all critical surfaces are free from any contamination is the only acceptable condition for a safe takeoff.