There is a need to monitor flotation deinking operations, in order to better control their efficiency, reduce losses, and save fiber resources. The objective of this work is to understand the variations of ink removal efficiency and flotation yield at industrial scale. A preflotation bank has been instrumented with air probes, and parameters relevant to flotation operations (chemicals dosages, brightness, effective residual ink content (ERIC), pH, temperature, water levels in cells, rejects flows, consistencies) have been exported from the mill data logging system. Then, relationships among flotation parameters are investigated. Air content in preflotation primary cells is found to vary considerably over time. On the other hand, air content in secondary cells is much higher, but rather stable. Ink removal is enhanced by a higher air content in primary cells. High air content is also found to impair the flotation yield. Most air content variations are explained by opposite variations of pulp concentration. It is proposed that pulp concentration lowers air content, by causing stronger pulp flocculation. These results suggest that deinking flotation yield may be maximized by running the flotation bank at the highest possible pulp concentration, while maintaining the target on the effective residual ink content.