When backing a commercial vehicle, what is the safest method?

Backing a commercial vehicle is dangerous because you cannot see everything behind the trailer. The safest approach is to use a helper whenever possible and to back slowly. A helper should stand near the back of the vehicle in a position where the driver can see them in the side mirror, and driver and helper should agree on hand signals before backing begins, including a clear signal to stop. The driver should back slowly so any developing problem can be corrected with minimal damage. Quick backing reduces reaction time and increases jackknife risk. Mirrors alone are insufficient because of large blind spots directly behind a tractor-trailer. Backing in a straight line is preferred where possible because turning while reversing rapidly increases the chance of jackknifing.