Under which conditions is the windshield heat set to low?

The correct condition under which the windshield heat is set to low is when the aircraft is in cruise at above freezing temperatures. During cruise flight, especially when ambient temperatures are above freezing, there is a reduced risk of icing on the windshield. Setting the heat to low in these circumstances helps maintain visibility while conserving energy, as maximum heat is unnecessary and could lead to premature wear on the heating elements or contribute to higher operational costs.

In the context of pre-flight checks, it is typical to ensure all controls and systems are functioning, and an appropriate setting for the windshield heat would be validated during this stage. However, setting it specifically to low is not necessarily practiced unless conditions warrant such an adjustment.

When the aircraft is taxiing, it may be more beneficial to have the windshield heat set at a higher level to prevent potential icing or fogging caused by varying speeds and increased moist air interactions, particularly if the temperature is low.

In the approach for landing, the windshield heat is often kept higher to ensure optimal visibility as safety is prioritized during this critical flight phase, especially if the weather conditions are uncertain.

Thus, under cruise conditions at temperatures above freezing, maintaining windshield heat at a low setting balances visibility needs and energy efficiency.