The biggest safety implication with using a forklift to elevate personnel is the fact that one is using a machine that is inherently unstable by design and which becomes more unstable the higher the work platform is raised. Most straight mast forklifts and variable boom forklifts have a three point suspension system. This is a definite safety disadvantage. Most aerial work platform machines designed for lifting personnel have a four point suspension system which increases the safety factor. This is a definite safety advantage.

Straight mast forklifts are more stable when lifting than variable boom forklifts as the combined center of gravity shifts toward the mast on the front end of the machine. This is the wider portion of the imaginary stability triangle. Variable boom forklifts are less stable when lifting than straight mast forklifts as the combined center of gravity shifts toward the variable boom base on the rear end of the machine. This is the narrow portion of the imaginary stability triangle.

Rough terrain forklifts also are affected by many unpredictable physical factors that can cause the combined center of gravity to move beyond the imaginary stability triangle. These include wind gusts, ground shift, and uneven tire pressure from tire air leaks. These factors have a greater impact on the variable boom forklifts due to the combined center of gravity location on the narrow end of the imaginary stability triangle.

Straight mast machines usually require the operator to raise the forks and in a few cases to also drive forward slightly. These operations are not to be conducted simultaneously. Variable boom machines require the operator to boom up/down, to boom out/in, and to maintain the forks level simultaneously, This is done while also ensuring that the boom angle and boom length do not exceed the load chart diagram. This requires that a variable boom forklift operator have a greater degree of skill and knowledge of their machine.

NIOSH fatality reports indicate that many variable boom forklift operators had neither the skills nor knowledge to operate the equipment safely. How many similar operators are out there on construction sites?

The question that should be asked is do you want to risk lives to perform a work task by using a personnel work platform attached to an unstable machine?