Flyburg
There have been cases of jets overflying the track system, having to do an emergency descent and triggering TCAS R/As. Most random routes overflying the NATS will cross them at some point. The requirement is to align the aircraft's track with the nearest organized track, offset and then begin the descent, time permitting. I now ask for flight plans above the NATS to follow the routing, if the planned level is above 410.