What does the probes anti-ice switch control?

The probes anti-ice switch is specifically designed to control the heat applied to the Pitot tubes, which are critical for accurate airspeed readings. Ice accumulation on these probes can obstruct airflow and lead to erroneous readings, potentially compromising flight safety. By activating the anti-ice system, electrical heating elements are engaged to prevent ice from forming, ensuring that the Pitot static system functions correctly without misleading data from the airspeed indicator.

The need for this functionality becomes particularly important in cold weather environments where icing conditions are a concern. Therefore, option C is correct as it directly relates to the operational purpose of the probes anti-ice switch.

Other options do not accurately reflect the purpose of the anti-ice switch: altitude calibration involves adjustments to altitude readings separate from probe heating, electrical voltage supply is a more general term that does not specifically pertain to the anti-ice function, and static pressure regulation pertains to different aspects of pitot-static system function rather than preventing ice formation.