High Risk Work Licence - Tower Crane (CT) common mistakes
High Risk Work Licence - Tower Crane (CT) · Understand the traps and how to avoid them.
Confirming a load is within capacity by checking only the boom/jib length and the load weight, without applying the load chart's radius, reeving, or configuration corrections for the actual setup.
Candidates memorise chart numbers as a single figure and forget the chart is a family of tables keyed to radius, boom/jib configuration, counterweight, and number of falls; the exam deliberately gives a load whose weight is under the headline capacity but over the capacity at the working radius.
What to do instead
Work every capacity question through a fixed sequence: identify configuration and reeving, convert the given geometry to actual working radius (including hook height and jib deflection allowance where stated), select the correct chart row/column, then compare gross load (load plus all lifting gear). State the chosen capacity and the margin explicitly so the reasoning is visible.
Treating the rated capacity as a fixed number that does not change while slewing or trolleying, and answering that a load known to be safe at one radius remains safe as it is moved outward.
The relationship between radius and capacity is a curve, not a constant, and candidates who only ever saw static examples do not internalise that increasing radius reduces capacity continuously; exam items that describe a trolley-out manoeuvre catch this.
What to do instead
Before any travel or trolley-out answer, compute capacity at the furthest radius the load will reach, not the starting radius. Practise by tabulating capacity at three or four radii for a sample chart and identifying the radius at which the given load becomes non-compliant.
Estimating load mass from the number of items or from a rough visual impression instead of using mass per unit, volume and density, or documented weights, and omitting the mass of slings, spreaders, and hook block from the gross load.
Candidates confuse volume with mass, forget that a cubic metre of concrete, sand, or steel differs by an order of magnitude, and treat rigging as weightless because it is 'part of the crane'.
What to do instead
Adopt a written estimation method: unit mass x quantity, or volume x density, plus a stated allowance for lifting gear; add a percentage for unknown or wet material and record it. In answers, show the arithmetic and name the density or unit mass used.
Choosing lifting gear by 'looks strong enough' or by matching sling diameter to load weight alone, ignoring the effect of sling angle, the number of legs sharing load, and the mode factor for the hitch used.
The relationship between leg tension and included angle is counter-intuitive; candidates underestimate how steeply tension rises as slings flatten, and they do not apply different factors for basket, choke, and single-leg hitches.
What to do instead
For every sling question, calculate or state leg tension using the angle (or the WLL reduction factor for the included angle), apply the correct mode factor for the hitch, and confirm the WLL of the weakest component including shackles and hooks. Memorise the standard angle/tension multipliers and practise a choke versus basket comparison.
Answering wind questions with a single blanket limit rather than distinguishing the crane's in-service and out-of-service wind limits, the effect of sail area on the load, and the manufacturer's stated figures.
Candidates remember one number quoted in training and apply it to every scenario, not realising that limits differ by crane, by load configuration, and by whether the crane is working or parked, and that the load itself can act as a sail.
What to do instead
Frame every wind answer around three elements: the manufacturer's in-service limit, the out-of-service/park limit, and the load's sail area and shape. State that the manufacturer's manual governs and describe the action taken at each threshold, including stopping, lowering, and parking per the manual.
Describing powerline safety as 'keep clear' without stating the specific approach distances, the role of the spotter, and the procedure if contact occurs.
Candidates recall the general principle but not the regulatory distances or the fact that a spotter, tiger rail, or limiting device may be required, and they confuse 'de-energised' with 'safe' without lock-out and verification.
What to do instead
Learn the approach distances that apply in your jurisdiction and quote them with the voltage bands. Structure answers as: identify voltage, establish exclusion zone and barriers, use a dedicated spotter with a positive communication method, and if contact occurs, keep everyone clear, do not touch the crane, and call the network operator and emergency services.
Treating the pre-start inspection as a quick visual walk-around and failing to name function checks of specific safety devices such as limit switches, the moment/overload limiter, the anemometer, and the anti-collision system.
Candidates conflate 'check the crane looks fine' with a documented inspection regime and do not know which devices must be proven operational before work begins.
What to do instead
Answer inspection questions with a structured checklist: structural items (mast, jib, tie bars, bolts, welds, corrosion), rope and reeving, brakes and clutches, then function tests of each safety device and the logbook entry. Name the device, the test performed, and the action if it fails (lock out, tag, report, do not operate).
Reporting a defect verbally to a colleague and continuing to operate, rather than applying the isolation, tagging, and documented reporting process and knowing which defects are grounds to stop work.
Candidates underestimate the legal weight of the logbook and the stop-work authority of the operator, and they assume minor defects can be worked around.
What to do instead
State the sequence explicitly: stop, secure the load, isolate and tag, record in the logbook, notify the supervisor and responsible person in writing, and do not return the crane to service until the defect is rectified and signed off. Classify example defects as stop-work or monitor.
Giving signalling and communication answers that name only hand signals, without covering the dedicated signaller requirement, blind lifts, radio failure fallback, and the rule that any person may stop the lift but only the nominated signaller may direct it.
Candidates learn the hand signal chart but not the authority structure, so they miss questions about who may give a signal, what happens when radio contact is lost mid-lift, and how multiple cranes on site coordinate.
What to do instead
For each communication scenario, identify the nominated signaller, the agreed signal method and backup, the emergency stop signal that anyone may give, and the procedure for loss of communication (stop and hold, then resume only on re-established contact).
Describing emergency and shutdown actions vaguely, such as 'lower the load and park the crane', without the ordered steps for a power failure, a brake failure, an approaching storm, or an out-of-service park including slew brake release and weathervaning.
Candidates treat shutdown as a single action and do not distinguish an end-of-shift park from an emergency stop or a storm park, each of which has different steps and different risks.
What to do instead
Prepare three separate ordered sequences: end-of-shift secure, emergency stop and incident response, and out-of-service/storm park per the manual (including free-slew and leaving the jib in the specified direction). Rehearse the order and the reason for each step so the answer explains why, not just what.