I wasn't able to find specific regulations or manufacturer guidelines that discuss using platform ladders as substitutes for extension ladders. However, here is some general safety advice regarding platform ladders. Before using any elevating platform, inspect the job site for potential hazards such as ditches, drop-offs, holes, bumps, obstructions, debris, untamped earth fills, overhead obstructions, electrical wires, moving vehicles, oncoming traffic, hazardous atmospheres, and weather conditions. [2]

[1] Always ensure the work platform is used only in accordance with the manufacturer's or owner's operating instructions and safety rules. Before each elevation of the work platform, check for overhead obstructions and high-voltage conductors, ensuring a minimum safe distance is maintained. Make sure the work platform is elevated only on a firm and level surface. Ensure the load and its distribution on the platform are within the manufacturer's rated capacity, and never exceed this limit. If required, use outriggers or stabilizers according to the manufacturer's instructions. Confirm that platform guardrails are properly installed and gates or openings are closed, and that all occupants' safety belts are correctly fastened. Personnel should maintain a firm footing on the platform, and safety harness/lanyard devices fixed to approved attachment points should be used by all occupants. The use of railings, planks, ladders, or any other device on the work platform, except as provided by the manufacturer, is prohibited. [3] [8] [10] [11] [12]

To prevent slip and fall hazards, keep the platform, shoes, and steps free from oil, mud, grease, and other slippery substances. Always keep both feet on the platform floor while working and traveling with the aerial lift, and do not lean over or stand on platform guard-railings. Ensure that platform guardrails are not damaged and the entry gate is closed after entering the platform. [6] [7] [9] [4] [5]