What is the safe maintenance sequence?
The fixed order for AGL maintenance: plan and get the permit, brief, isolate and prove dead, work within the permit, test and restore, then hand back and record.
A safe maintenance sequence is the fixed order in which AGL work is planned, prepared, isolated, carried out, tested and handed back. It exists so that the circuit is dead before anyone touches it, the work stays inside what was approved, and nothing is left behind or energised unexpectedly when the job ends. It brings together the permit, the briefing, lock-out tag-out at the CCR, the controls at the work site and the restoration that follows.
The steps run in order and none is skipped. Plan the job and obtain the permit to work and the approval of airport operations or ATC. Brief the team on the task, hazards, work area, PPE, tools, escort and FOD. Isolate at the CCR: switch it off, select local control and isolate or inhibit the remote control path (tower or ALCMS) so it cannot be started from there, isolate its incoming supply (and any standby CCR or changeover arrangement that could feed the same loop) and its output to the series circuit, lock and tag every isolation point, then prove dead with a tester that has itself been proved, and earth as the procedure requires, because a dark fixture is not a dead circuit. Work only within the scope, area and time of the permit, with tools counted in and out. Restore by counting tools out, removing the working earths as the test method requires, testing the circuit (insulation resistance) while it is still isolated and discharging it afterwards, removing each lock by its owner and energising only on the authorised person’s word, then checking circuit current and lamp operation on the brightness steps. Close out by handing back the permit, telling ops or ATC (and updating the NOTAM or lighting status if service was affected) and recording the work.
Frequently Asked Questions
Q1What is the safe maintenance sequence?
It is the fixed order in which AGL maintenance is planned, prepared, isolated, carried out, tested and handed back. Following the same steps every time means the circuit is dead before anyone touches it, the work stays inside what was approved, and nothing is left behind or energised unexpectedly when the job ends.
Q2What are the steps, in order?
Plan and obtain the permit and approvals, brief the team, isolate at the CCR with lock-out tag-out and prove dead, carry out the work within the permit, test and restore, then close out by handing back the permit and recording the work. The steps are not reordered or skipped, and isolation always comes before any hands-on work.
Q3Why must the circuit be isolated before work starts?
An AGL series circuit is one loop driven by the CCR, so the whole loop is live while the CCR runs, and a live loop is never opened. A dark fixture does not mean a dead circuit, and the primary cable and connectors of an isolation transformer stay in the loop. The CCR is switched off, set to local control and its remote control path (tower or ALCMS) isolated or inhibited so no one can start it remotely, its incoming supply (and any standby CCR or changeover arrangement that could feed the same loop) and its output to the series circuit are isolated, every isolation point is locked and tagged, and the circuit is proved dead with a tester that has itself been proved and earthed as the procedure requires, before anyone touches a cable or connector.
Q4What does the permit to work cover?
It records what work is to be done, where, when and by whom, and that airport operations or ATC have approved access to the area. The team works only within that scope, area and time. If the job changes or runs over, work stops and the permit is reviewed or reissued rather than stretched.
Q5Who removes the locks and re-energises the circuit?
Each person who fitted a lock removes their own, and only after the work is finished, tools are counted out and the circuit has been tested (including insulation resistance) as the procedure requires. The circuit is re-energised only on the word of the authorised person, who first confirms that everyone is clear and that the airport has been told. Circuit current and lamp operation are then checked on the brightness steps before the work is handed back.
Q6What happens at close-out?
The permit is handed back and closed, airport operations or ATC are told the work is complete and the equipment is back in service (with the NOTAM or lighting status updated if service was affected), and the work is recorded, including any defects found or work left outstanding. The work site is checked for tools and debris so nothing is left on the airfield.
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