Which of the following is NOT a method used for ice detection?

The correct answer identifies pressure gauges as NOT a method used for ice detection. Ice detection typically involves methods that directly measure conditions conducive to ice formation or the presence of ice itself. Ice detection probes actively sense ice accumulation on surfaces, while temperature sensors monitor critical temperatures that indicate the potential for ice to form. Visual assessments allow crew members to see and detect ice visually, which is a practical and immediate method for identifying ice presence.

In contrast, pressure gauges are primarily used to measure and monitor pressure levels in a system and do not provide direct information about the presence of ice. Therefore, they are not suitable for ice detection purposes.