Method for detecting the tilt of a floating roof floating on a medium stored in a tank

The present disclosure concerns a method for detecting the tilt of a roof floating on a medium in a tank, wherein a radar level gauge is mounted in a fixed position on the tank and emits signals in the direction of the roof. The method includes: determining and recording the level of the floating roof during a period of time including some filling/emptying cycles of the medium in the tank, detecting and recording the echo amplitudes of the echo signals during said period of time, filtering the echo amplitudes and recording the filtered echo amplitudes, calculating the gradient of the filtered echo amplitudes, calculating a threshold value for a tolerable deviation of the gradient of the filtered echo amplitudes, and generating an alert message that a roof tilting is detected if the deviation of the gradient falls behind the threshold.