Catapult effect: understanding it to avoid it

Small movement of the wheels can lead to a large movement of the basket

This post is 1 an old.

The IPAF has recently published a safety awareness leaflet about the catapult effect.

The MEWP catapult effect occurs when stored energy or an impact to the MEWP’s structure causes a whiplash effect, which travels through the boom to the platform.

This situation can generate an ejection from the platform of any occupant, leading to serious injury and death, especially if occupants in boom machines are not wearing a safety harness.


When the platform is caught or snagged, it can feel to the operator that no boom movement is happening, but it may be the case that one or more wheels or outriggers are lifting clear off the ground. As and when the platform is released, wheels or outriggers return to the ground, and the stored energy or inertia creates a whiplash effect. Even a small movement at ground level could create a whiplash effect which is sufficient to eject platform occupants, tools or other materials.


The catapult effect can also occur when driving in the stowed position, so make sure occupants wear personal fall protection equipment (PFPE) that is always connected to the designated anchor point. Occupants must always use a full body harness and an adjustable restraint lanyard, adjusted as short as possible, when using MEWPs.

IPAF-catapult effect

Key advice on the new leaflet is divided into three sections:

  1.  Planning the job
  2.  Evaluating the work environment while making a site risk assessment
  3.  Checking the maintenance and guaranteeing operators are trained.


Using a spotter would help to eliminate many dangerous situations.
A spotter can identify hazards when another operator is driving the MEWP over uneven ground. Using a spotter is an inexpensive solution that can be easily implemented.

Brian Parker, IPAF’s head of safety and technical, brought his insights to LHI on the catapult effect:

Experienced users of MEWPs will doubtless have encountered at least one catapult situation, and so will be aware of the risks and the potential energy that is generated; without a harness with the correct fall-restraint lanyard clipped to the anchor point, it is virtually impossible to counter the catapult effect, even when manoeuvring the MEWP in the lowered or stowed position. This updated leaflet is a timely reminder for operators of all levels of experience that the catapult effect can easily lead to serious incidents with catastrophic outcomes; we urge people to view and download this latest IPAF leaflet, to read and understand the simple safety messages and build them into your safe work planning.

Read our last article

6 questions before renting a MEWP

Prepare in a few minutes your brief for your rental supplier!
Share it !

Most popular articles