For each potential fire pixel over land, pixels where the background characterisation was successful but the absolute threshold test failed, a series of contextual threshold tests are used to test confirmation of the potential fire pixel.

These tests examine the S7 and S8 brightness temperatures corresponding to potential fire pixel signals and compare these to the mean signals from the background window, with the exact thresholds adjusted to take into account the variability of the background window as measured by the mean absolute deviation.

Six tests are carried out successively and, following the results of these tests, a potential fire pixel is classified as a confirmed fire pixel or classified as a non-fire pixel.