Air traffic being in constant increase generates higher movement frequencies on airports. To guarantee at any time the highest security level, equipment used during the different flight phases have to be at optimal operating status. This includes the Airfield Ground Lighting facilities.
These conditions are even more necessary to be fulfilled in low visibility conditions as airports have to be able to operate in CAT I, CAT II or CAT III categories with all related serviceability conditions. Regular controls of the installations are therefore required in order to confirm the highest possible level of operation.
Some of the airport’s maintenance teams use human visual examination to check the light intensity. Sometimes they replace the lamp when it is dark or dull and at times they replace when it is not even needed as they change entire group pf lights at definitive intervals. It is inevitable that the maintenance team ends up changing some lights that were still within acceptable limits. ICAO studies have shown that human eye is only able to detect a loss in intensity once it is decreased to 30% of its original value. To human eye, the light produced may be bright enough but it may not be visible from a distance. Damage, scratches and rubber deposits in prisms is not usually detected. Human eye is also not able discern whether a light is incorrectly oriented or not. With every touch down, aircraft leaves behind rubber which is deposited on hot prisms of inset lights which reduces the photometric characteristics of the light fittings. During fog this situation worsens which is further a potential safety risk. If the RVR calculations that pilots use to determine if it is safe to take off or land presuppose that runway lights are working correctly to ICAO specifications. If pilots operating in poor visibility conditions are further hampered by ineffective lights, the light will have to be diverted or runway needs to shut down. The problem can only be understood from the pilots’ perspective who wants to land in the night specially in low visibility condition.
Airports have a duty to give pilots the best visual cues they can at the moment pilot needs them. When airport operators are able to maximize the capacity and safe operation by keeping on top of maintenance then they have less unplanned maintenance or runway closure.
The benefit of the photometric testing is that it reduces maintenance costs by enabling airfield technicians to replace or repair on fixtures that require maintenance and on pointing problem fixtures before they fail.
FAA advisory circular 150/5340-26B maintenance of airport visual aid facilities which require light output to be aligned in the proper direction and equal to or greater than 70% of the required design output of the light fixture when it is new. The minimum acceptable/threshold values for light output are clearly defined in Annex 14 of ICAO which is 50% of the light required design value. A light is deemed to be unserviceable when the main beam average intensity is less, than 50% of the value specified for that of a new light
The Total degradation of light output can be attributed to:
- Contaminants inside and outside the fittings
- Degradation of optical components
Till the years ‘80s, means used to perform measurement were basic and limited to manual checks of the lights with a luxmeter. With limited access to runways and with technological upgrade the system has been advanced with evolution of mobile photometric testing equipment which can be fitted on a vehicle and tested on the airport in a much quicker and efficient manner thereby reducing the maintenance time for airfield maintenance team.
Our technology partner, FB Technology, a France based leading photometric test equipment manufacturer has developed a dynamic measurement device PAC – Photometrical Airfield Calibration aiming at giving in real time the luminous intensity of runways and taxiways fittings. This device has been certified by the French Civil Aviation Technical Services (STNA) as an equipment to be used for maintenance and calibration of AGL equipment of CAT I, II / III runways.
Furthermore, PAC generated reports give precise and quick information on the AGL status and help maintenance teams to follow up their installations by planning their site maintenance schedule rather than operating only with curative maintenance therefore developing a reliable preventive maintenance programme.
Fittings measurements have been carried out using the Photometry System PAC version 5 (Bi-directional Photometric Airfield Calibration). Measurements have been effected with AGL supplied at maximum brightness level 6.6A.
The process requires 3 steps: –
- Cleaning of light fixtures: Before conducting a photometric test, it is inevitable need to clean all the light fixtures else the photometric output may be incorrect. The cleaning system with efficient to save maintenance time. For more details, please refer to https://www.vardhmanairports.com/sodice-airfield-lighting-soda-powder-cleaning-equipment/
- Mobile photometric testing: The mobile photometric testing equipment is designed to mount on the maintenance vehicle and is used to evaluate all inset and elevated lights. As airport runway access time is limited, photometric measurement runs need to be completed as quickly as possible and can be conducted at speeds up to 60 km/hr without affecting accuracy. The test report generated provides the candela value of each light and identifies any defect requiring action to be taken. It also makes it possible to monitor lamp ageing from previous runs so that all the results for a runway or taxiway can be compared. This enables the airfield lighting department to plan its operations and manage its stocks as efficiently as possible. If the lamp is not defective although the system indicates a low intensity, the identification facility guides the search and thus optimises maintenance operations. For more details, please refer to https://www.vardhmanairports.com/photometric-airfield-calibration/
Mobile photometric testing completed in Amritsar Airport in year 2018 by Vardhman
- Workshop photometric testing: The lights fittings which have failed the test are removed from service due to serviceability levels and the fitting undergoes an overhaul where any faulty or worn components are replaced. The lamp is also changed and the fitting fully cleaned Undergo water tightness test. The lights are then tested on the work bench and if it passes photometric test is kept as spares to be used to replace the next set of faulty light fittings. For more details, please refer to https://www.vardhmanairports.com/photometric-workshop-equipment/
Annex 14, Volume I, recommends regular measurements of light intensity of Airfield Lighting Installations, at least twice a year with a Civil Aviation Certified device. Since October 2003, airports have to submit compliancy report of their installations against the ICAO standards. (Amendment no. 5 to Annex 14). In the recent years, almost all Civil Aviation Authorities have changed the rules of the Maintenance of Airport Lighting by stressing the requirement of frequent photometric testing up to once a month for runway lighting. This necessitates the requirement for a preventive Maintenance system for Airfield Lighting that meets the safety regulations. It has to be regularly monitored to ensure that it meets ICAO standards.
There are additional systems such PAPI calibration, Airfield Guidance Signs Photometric calibration and AGL torque calibration equipment for maintenance of AGL equipment which may be used in additional to above systems. For more details, please visit our website www.vardhmanairports.com
Vardhman Airport Solutions Pvt Ltd is a premier organization providing quality product, solution and services for Airfield Lighting system, Visual docking guidance system, Photometric equipment & Security Systems for commercial & defence airports to elevate the airside infrastructure to the next level.
