The datalink is designed to deliver any message and its associated response within 16 seconds 95% of the time, and 20 seconds 99% of the time. This excluding the operator delay, that means the time the crew takes to consider the message and produce a response. While it is true that in the recent past, network congestion led to subpar datalink performance, recent operational statistics show a marked improvement; the 95th percentile is in fact returned in 10 seconds, and the 99th percentile in 24 seconds (September 2017). The bottom line is that in the European en-route environment, the controller will always have the plain old RT available to use as the safety critical communications channel. Controller training and experience will equip the controllers with the necessary skill to determine when to use datalink and when to use RT.