Which type of vehicles must possess proper markings while on the airport apron?

Proper markings are crucial for enhancing safety and visibility on the airport apron, where vehicle and aircraft operations intersect. Non-self-propelled equipment, which can include tugs, trailers, or other towing vehicles, must be clearly marked to ensure they are easily identifiable. This is essential for both ground personnel and pilots to understand the types of vehicles in operation around them, as well as to minimize the risk of accidents.

Markings help indicate important information, such as the vehicle type, its function, and its operational status, facilitating safer interactions on the busy apron. Although other vehicle classifications play significant roles, non-self-propelled equipment has specific requirements due to their often larger size and the potential complexities involved in their operation. Properly marking these vehicles is vital as it contributes to overall situational awareness and helps in maintaining organized flight operations.