Under what condition can a ground vehicle be backed up without a guide?

Answer: D — No condition is allowed to back up without a guide

Backing up a ground vehicle without a guide is not permitted under any condition due to safety regulations and operational best practices. This rule is in place to prevent accidents and ensure the safety of both vehicle operators and pedestrians or other personnel in the vicinity. While there are various types of vehicles, including small bag tractors, passenger cars, and utility vehicles, the requirement for a guide remains consistent across all vehicle types. A guide can help ensure that the vehicle moves safely without risking collisions or jeopardizing the safety of those around it. Therefore, adherence to this guideline is essential for maintaining a safe environment, particularly in busy areas like airports where ground traffic can be complex and potentially hazardous.