From experience, TMS recommends that prior to initial AGL system installation, and so subject to wear, all light fittings are tested to identify any potential problems, and certified. This testing, which can normally be undertaken in the TMS laboratory on a MALMS Photometric Bench (or if available on-site, the MALMS Workshop), allows for the return of failed fittings to the manufacturer for appropriate rectification.   The importance of this approach is highlighted by a project at London Heathrow. TMS undertook a 100% testing of AGL fittings (using MALMS Workshop) as part of a recent runway refurbishment program. This proved to be an important factor in achieving AGL performance that exceeded ICAO standards at the time of commissioning. As a result, the testing programme is now being repeated under the current refurbishment project.