Objective measurement of the quality of airport lighting whilst in service

Abstract

This paper contributes to the science of measurement and control by outlining a unique methodology for objectively assessing the luminous intensity of all luminaires forming an airport landing lighting pattern, whilst in service, to check that the lighting pattern conforms to the strict standards set by airports’ governing body within the UK the Civil Aviation Authority (CAA). Central to this methodology is a novel air-based measurement system consisting of charge-coupled device (CCD) cameras and dedicated image-processing software. This prototype measurement system is placed inside the cockpit of an aircraft and is used to take images of the airport landing lighting system whilst the aircraft approaches the airport. Developed image-processing techniques then allow unique luminaire identification and extraction from the hundreds of luminaires within the airport lighting pattern. The corresponding luminous intensity and alignment of each luminaire is derived using dynamic position and orientation information estimated from a visual environment model. By obtaining luminous intensity and alignment information for each luminaire within the pattern, it is then possible to derive its associated isocandela diagram. This then allows an assessment to be made regarding the luminaires’ conformity to the CAA standards. The unique system has been tested at Belfast International Airport, the results of which are documented within this paper. The results indicate that further work is necessary if the system is to be fully functional. Currently it takes approximately 35 h to filter the results for one complete pattern. In addition, a maximum error of 40% is reported between derived and actual luminous intensity measurements for a given luminaire. The reasons for this discrepancy are highlighted in the discussion and improvements are currently being made to the system to account for these. However, the results and the work reported within this paper reflect the belief that digital imaging can be utilized to automate many physically large photometry problems within the fields of science and engineering. The methodology described for the development of this measurement system is unique and we believe extends the science of automated dynamic measurement systems.