An important aspect of rainfall estimation is to accurately capture extreme events. Commercial microwave links (CMLs) can complement weather radar and rain gauge data by estimating path-averaged rainfall intensities near ground. Our aim with this paper was to investigate attenuation induced total loss of signal (blackout) in the CML data. This effect can occur during heavy rain events and leads to missing extreme values. We analyzed three years of attenuation data from 4000 CMLs in Germany and compared it to a weather radar derived attenuation climatology covering 20 years. We observed on average twelve times more blackouts in the CML data than we would have expected from the radar derived climatology. Blackouts did occur more often for long CMLs, which was an unexpected finding. In conclusion, both the hydrometeorological community and network providers can consider our analysis to develop mitigation measures.