What is the outside air temperature limit for using wing anti-ice on the ground?

The correct answer regarding the outside air temperature limit for using wing anti-ice on the ground is that it is 5° or below. This limit is established because the risk of ice formation on the wings increases at temperatures that are at or below freezing, particularly in conditions where moisture is present. The operation of wing anti-ice systems is crucial for ensuring safe aircraft performance and handling during takeoff and taxi, as ice accumulation can severely impact the aerodynamic properties of the wings.

At temperatures above 5°, the likelihood of ice accumulation decreases significantly, hence, the use of wing anti-ice is not typically required, and using it unnecessarily could lead to overheating or damage to the system. Understanding these thresholds helps operators make informed decisions during ground operations in potentially adverse weather.