Landing light for airport runway - avoids damage when surrounding water freezes by allowing air retained in peripheral cavity to compress

摘要

The landing light for an airport runway has a sealed casing (1) which fits into a container (3) embedded in the runway itself. The casing (1) has a peripheral cavity (2) which is full of air when the container (3) is dry but which retains air when the cavity (2) fills up with water. When the water freezes, the air trapped in the cavity (2) compresses, allowing ice to form without exerting pressure on and damaging the casing (1).