DOGGING & SLINGING MISTAKES THAT PUT LOADS IN THE AIR WRONG
The crane gets the attention, but most lifting incidents come down to what happens at the hook. Dogging and slinging is where the load is estimated, the gear is selected and the lift is directed, and a mistake here puts the load in the air the wrong way before the crane has done anything wrong.
It only takes one bad decision at the sling to turn a routine lift into a dropped load. A sling angle that halves the safe capacity, a weight that was guessed rather than known, or a chain with a worn link can all fail without much warning, usually with people nearby.
This guide covers the dogging and slinging mistakes that cause the most damage, what they actually lead to on site, and how proper gear selection and inspection keep every load balanced, secure and within its limits.
1.Guessing the load weight
The weight is estimated by eye or from memory instead of being confirmed. Underestimating the load means the gear and crane can be overloaded without anyone realising, right up until something fails. A guessed weight is one of the most common reasons slings and shackles are pushed past their limits.
How a professional handles it: The load weight is established from documentation, drawings or a load cell before gear is selected, not guessed. A competent dogger works from a known weight so every component is chosen with a real margin of safety.
2.Ignoring the effect of sling angle on capacity
Slings are used at wide angles without accounting for the tension it puts on each leg. As the angle from vertical increases, the load in each sling leg climbs sharply, so a load well within the sling rating at a steep angle can overload it at a flat one. Crews routinely overload slings without knowing it because they read the tag rating and ignore the geometry.
How a professional handles it: Sling angles are kept within safe limits and capacity is worked out for the actual angle used, following the derating rules in AS 2550. A trained dogger accounts for the geometry so each leg stays within its working load limit.
3.Exceeding the working load limit of the gear
Slings, shackles, chains and hooks are used beyond their marked working load limit, or gear is mixed without checking the weakest component. The whole rig is only as strong as its lowest-rated part, and overloading any one item can cause it to fail and drop the load. This is a direct cause of dropped loads and the injuries that follow.
How a professional handles it: Every component is selected so its working load limit exceeds the load it will carry, with the whole assembly rated to its weakest link. A competent dogger matches the gear to the load and the configuration every time.
4.Using damaged or uninspected lifting gear
Slings with cuts, chains with stretched links, and shackles with worn pins are used because they were on the truck and looked good enough. Damaged gear can fail well below its rated capacity, and wear is often not obvious until the item is examined closely. Continuing to use gear that has not been inspected is gambling with the load and everyone under it.
How a professional handles it: Lifting gear is inspected before use and taken out of service at the first sign of damage or wear, with periodic thorough examinations kept up to date. Following the inspection requirements in AS 2550 keeps unsafe gear off the hook.
5.Poor load balance and centre of gravity
The load is slung without working out where its centre of gravity sits, so it tips, swings or slides once it leaves the ground. An unbalanced load can rotate suddenly, slip out of the slings or shift the crane's radius unexpectedly. This is a frequent cause of loads swinging into people or being dropped during the pick.
How a professional handles it: The centre of gravity is assessed and the slinging arranged so the load lifts level and stable. A trained dogger positions the slings so the load stays balanced from lift-off to landing.
6.No protection against sharp edges
Slings are run over sharp corners and edges with no packing or softeners. A tensioned sling under load can be cut through by an edge in seconds, and synthetic slings are especially vulnerable. A cut sling fails suddenly and drops the load without warning.
How a professional handles it: Edge protection or softeners are used wherever a sling contacts a sharp corner, and packing is treated as standard rather than optional. A competent dogger protects the gear so it holds its rated capacity throughout the lift.
7.Unclear or non-standard communication with the crane operator
Signals are improvised, hand signals mixed with unclear radio calls, or more than one person directs the crane at once. If the operator misreads a signal the load can move the wrong way into structures or people. Confused communication has caused loads to be lowered, slewed or dropped at the wrong moment.
How a professional handles it: One dogger directs the lift using standard signals or clear radio protocol, with everyone agreed on the plan before the pick. Clear, single-point communication keeps the operator and the load working together.
8.Slinging a load without a lift plan for anything non-routine
Awkward, heavy or unusual loads are slung on the fly without planning how they will be rigged and moved. Complex lifts have more ways to go wrong, and improvising the rigging leaves no margin when something does not go to plan. Many serious rigging incidents involve non-routine lifts that were treated as routine.
How a professional handles it: Non-routine lifts are planned in advance, with the rigging method, gear and load path worked out before the crane arrives. A qualified rigger or engineer prepares the lift so the crew is not improvising under load.
9.Working under or too close to the suspended load
Crew position themselves under the load to steady it or move faster, or the drop zone is not kept clear. A suspended load can swing, slip or fail, and anyone beneath it is exposed to a crush injury or worse. This is one of the most common contributors to fatal lifting incidents.
How a professional handles it: No one works under a suspended load, and tag lines are used to control it from a safe distance. A competent dogger keeps the crew clear and controls the load without putting anyone in the drop zone.
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FREQUENTLY ASKED QUESTIONS
How does sling angle affect lifting capacity?
As the angle between the sling legs and vertical increases, the tension in each leg rises well above a straight vertical lift. A load that is safe on slings at a steep angle can overload the same slings when the angle is flattened out. That is why capacity has to be calculated for the actual angle in use, not just read off the sling tag.
What is the working load limit and why does it matter?
The working load limit is the maximum load a piece of lifting gear is rated to carry in normal use, marked on the item. It matters because a lifting assembly is only as strong as its lowest-rated component, so every sling, shackle and hook must comfortably exceed the load. Using gear beyond its working load limit is a direct cause of dropped loads.
How often should lifting slings and gear be inspected?
Lifting gear should be visually checked by the user before every use and taken out of service at the first sign of damage or wear. On top of that, it needs a periodic thorough examination by a competent person at the intervals set under AS 2550. Keeping both up to date is what keeps unsafe gear off the hook.