What is INCORRECT about backing a heavy vehicle?

A Because you cannot see, you should back slowly until you slightly bump into the dock.

explanation

When you have to back, here are a few simple safety rules:
• Start in the proper position.
• Look at your path.
• Use the mirrors on both sides.
• Back slowly.
• Back and turn toward the driver’s side whenever possible.
• Use a helper whenever possible.
[California Commercial Driver Handbook]