Results are presented describing the cumulative fading distribution de
termined over 3 consecutive years during the fading season (June-Augus
t) on a 51-km terrestrial microwave link. The fading is more severe at
low signal levels than expected from the International Radio Consulta
tive Committee predictions based on accumulated data from many such li
nks over the years. An attempt is made to isolate the cause of the dee
p fading in terms of the atmospheric processes involved.