AGL Pit Installation and Replacement

An airfield ground lighting fitting does not sit on the pavement, it sits in it. The light is mounted in a base assembly, commonly called a pit or a can, set flush into the surface and wired back through ducting to the constant current circuit. Installing or replacing one is a concrete cutting job before it is an electrical one, and the pavement has to be handed back serviceable at the end of the shift either way.

A pit is formed or removed by coring around it at large diameter and lifting the unit clear. The reason is the surrounding slab: a percussive break-out fractures the concrete beyond the intended line, and on an airfield pavement that turns a fitting replacement into a bay repair. A clean core leaves a sound, square shoulder for the new base to be grouted into, which is what the reinstatement depends on.

Depths vary with the base type. A shallow base sits within the surface course; a deep base extends well below it and needs a correspondingly deeper core. Either way the hole has to be cut square and to depth, because a pit set even slightly proud or out of level is a trip and a foreign object debris risk on a surface where neither is tolerable.

The pit is only useful once it is connected. Primary cable normally runs in ducting, and secondary connections between pits often run in a chase cut into the pavement and resealed. That chase is the same discipline as crack chasing with far tighter tolerances: cut to width and depth, cleaned, the cable laid, and the chase sealed so the pavement is watertight again before the runway reopens.

Everything happens in the window the aerodrome gives you. Escorted access, an airside pass for every operative, a permit for every penetration, and debris control that treats a cored pit, a slug of concrete and a length of old cable as items to be counted out rather than swept up. Slurry is contained and removed: airfield drainage is not somewhere to put it. The surface is handed back serviceable and inspected before the first movement.

One example of the work at volume: AGL coring at Stansted Airport, 150 seating pots across a ten week programme of overnight possessions.

We are based at Little Westerhill Farm near Maidstone in Kent. Kent, London, Sussex, Essex and the wider South East are covered from our own yard, and longer programmes are mobilised UK wide. Pit work sits within our airfield ground lighting service and our aviation sector.