High Risk Work Licence - Non-Slewing Mobile Crane CN common mistakes
High Risk Work Licence - Non-Slewing Mobile Crane CN · Understand the traps and how to avoid them.
Treating the load chart as a single maximum figure and planning the lift from that number alone, instead of locating the actual boom length, radius and configuration on the chart before the lift is set up.
Candidates memorise one 'capacity' figure during training and carry it forward, not realising that capacity falls steeply with radius and that the applicable row depends on boom length, jib or fly configuration and whether the crane is pick-and-carry rated.
What to do instead
Practise reading charts by working backwards: from a measured radius and required boom length, find the rated capacity, then deduct the rigging and hook-block mass, and confirm the result is at or below the figure for that exact configuration. Do this on paper for at least ten different radius and boom-length combinations before the assessment.
Estimating load mass by eye or from the item's nominal size rather than calculating it from known mass, volume and density, and failing to add the mass of slings, spreader beams, shackles and the hook block.
Experienced hands rely on familiarity with common items, and the rigging mass is small enough to be forgotten until it pushes a near-capacity lift over the limit; unfamiliar or wet loads are also underestimated.
What to do instead
Adopt a written routine: identify the load, calculate or look up its mass, add every item of lifting gear and the hook block, add a margin for unknown content or absorbed water, and record the total before selecting gear. State the total aloud during the practical assessment so the assessor can see the reasoning.
Setting up with outriggers or tyres on ground that has not been assessed for bearing strength, voids, services or slope, and using packing that is too small or not load-spreading.
Setup is rushed on sites with time pressure, and firm-looking surfaces such as compacted fill, asphalt over a culvert, or a concrete slab over a basement conceal the real bearing capacity.
What to do instead
Before setup, inspect the whole footprint, check for services and voids, test the ground, and use purpose-made spreader pads sized to the outrigger load. Confirm the crane is level within the manufacturer's tolerance using the crane's level indicator, and recheck level after the first load is applied.
Relying on hand signals alone for critical lifts, or accepting signals from anyone on site rather than a designated, identifiable dogger.
Radio failure or background noise is common on site, and candidates assume anyone waving them on is authorised; multiple signal sources during a blind lift are a frequent cause of wrong movements.
What to do instead
Agree the communication method at the pre-lift briefing, nominate one signal person, and confirm radio channels and battery status with a test call. Stop the lift immediately if signals conflict or are unclear, and use a hands-free or relay arrangement for blind lifts rather than guessing.
Slinging loads without checking the included angle between legs, and selecting slings by eye without confirming the tag, WLL and condition.
Candidates underestimate how quickly leg tension rises as the angle opens, and assume any sling in the toolbox is serviceable; damaged or unmarked gear is often mixed in with good gear.
What to do instead
Calculate or look up the load factor for the actual included angle before rigging, keep the angle within the gear's rating, and inspect every sling for tag, WLL, cuts, broken wires, heat damage and distorted fittings before use. Reject unmarked or damaged gear and tag it out.
Skipping or superficially performing the pre-start inspection, particularly checking logbook and maintenance history, limit switches, and the condition of ropes, sheaves and hooks.
The inspection is treated as a box-ticking exercise under time pressure, and defects that are not immediately obvious, such as broken wires inside a rope or a slow limit switch, are missed.
What to do instead
Use a structured checklist in a fixed order, physically touch and test each item, function-test the limits and alarms where safe, and read the logbook for outstanding defects. Record findings as you go rather than from memory at the end.
Travelling with a suspended load or at excessive speed and radius, and failing to plan the route for ground condition, overhead lines, slope and pedestrian exclusion.
Candidates treat pick-and-carry as ordinary driving, forgetting that travelling with a load changes stability, braking distance and the rated capacity, and that the route may cross soft ground or pass under powerlines.
What to do instead
Plan the travel path in advance, walk it to check ground and clearances, confirm the crane is rated for pick-and-carry at that radius and configuration, keep the load as low and close as practical, use a spotter, and travel at walking pace with smooth braking and no sudden slewing.
Describing hazards only in generic terms such as 'powerlines' or 'soft ground' without linking each to a specific consequence, likelihood and control, and without assigning responsibility.
Candidates learn hazard lists by rote and reproduce them without applying them to the scenario given, so the risk assessment reads as a word list rather than a decision tool.
What to do instead
For each hazard, state the mechanism of harm, the people affected, the initial risk, the control in the hierarchy order, and the residual risk, then name who checks it. Practise on unfamiliar scenarios so the process, not the list, is what is recalled.
Not knowing the licence and duty-of-care boundaries: what the class authorises, what must be recorded, when a licensed dogger or rigger is required, and what to do when a lift falls outside the licence or the crane's rating.
Candidates confuse similar licence classes and assume site supervision carries the legal responsibility, so they do not recognise when they must refuse or escalate a lift.
What to do instead
Learn the class definition and its exclusions, the record-keeping obligations, and the circumstances requiring a licensed dogger. Rehearse refusing an unsafe lift: state the reason, the specific limit breached, and who is being notified, using the regulator's guidance as the reference.
Improvising in an emergency: lowering a load without a planned procedure, failing to secure the crane and isolate power, and not reporting the incident or defect through the correct channel.
Emergency response is rarely practised beyond a shutdown checklist, so under stress candidates act on instinct and omit isolation, exclusion zones and notification, and defects are noted verbally rather than recorded.
What to do instead
Learn and rehearse the emergency sequence for the specific crane: stop, lower or land the load if safe, apply controls, isolate and tag, exclude people, then notify. Practise writing a defect report and an incident notification with the facts, time, people and immediate action included.