When should the brakes of a vehicle be checked when approaching an aircraft?

The correct answer indicates that vehicle brakes should be checked when approaching an aircraft at a distance of 15 feet. Conducting a brake check at this distance is crucial for ensuring safety around the aircraft. At 15 feet, the driver can adequately assess the braking capability of the vehicle without being too close to the aircraft, which could pose a risk to both the aircraft and personnel.

The use of 15 feet as the designated distance allows for a balance between being close enough to the aircraft for effective operation and being far enough to manage safety and response time. The practice helps ensure that the vehicle can stop effectively if necessary, preventing accidents during aircraft servicing or loading operations.