The task was started without RAMS, TRIC card, or pre-job briefing, resulting in hazards and controls not being adequately assessed. The work was not sufficiently planned or supervised after the decision was made to replace the AC unit, leading to the task being completed using individual judgement rather than a structured safe system of work. An A-frame ladder was selected to access the work location although more suitable access equipment was available, increasing the risk of a fall. The technician ascended the ladder while carrying the trunking cover and did not maintain three points of contact, resulting in loss of balance and a fall from the ladder. The task had become routine and normalised, resulting in safety controls, risk assessment requirements, and procedural compliance being overlooked