When do the gear handle and red indicators illuminate on the T-6?

The gear handle and red indicators illuminate on the T-6 to indicate that there is an issue with the landing gear system. Specifically, this occurs when the nose gear is in transit, meaning it is not in the locked position, or when the main gear doors are not completely closed. This warning system is crucial for ensuring pilot awareness of the landing gear status, especially during critical phases of flight such as takeoff, landing, and maneuvering on the ground.

When the gear is not properly positioned, it poses a risk for the aircraft, making the illumination of these indicators an essential safety feature. The other scenarios presented in the options do not directly relate to the proper functioning of the gear system, which reinforces why the first choice accurately describes the condition under which these indicators would light up.