5.2.7.5 Difference in daylight/darkness perception

A visual surveillance system, including the camera sensors and display units, can produce an image that may result in the user having a different perception and capability to see objects/weather in varying light conditions. As part of the implementation and validation of the visual surveillance system, it will be necessary to understand the performance and any limitations of how the cameras perform in differing light conditions and will require the configuration to be optimised for the environment and tasks required. Validation activities have shown that the presented image in some technical platforms may appear brighter compared to the real-world conditions during dusk and dawn, prolonging the experience of daylight and enabling the ATCO/AFISO to see occurrences which are not possible to be seen in real life due to darkness conditions. Although this can be considered as a benefit from the situational awareness perspective, it could also pose new operational risks. It may be difficult for the ATCO/AFISO to judge when darkness has occurred, potentially leading to incorrect service provision or incorrect selection of airfield lighting. Equally, the image in true darkness may be optimised for a less noisy image to compensate for artificial light, but this could mean that meteorological elements may be harder to detect. The understanding of these differences should be part of the SAT test, the local safety assessment and conversion training; therefore, where appropriate, technical or procedural mitigations should be put in place. Technical improvements may include the provision of sunrise/sunset times and separate camera configurations that allow a user to view areas easier under certain light conditions.