Evening Ulm
Procedural E is Non-RADAR E i.e. IFR are separated from IFR using procedural separation standards such as VOR lateral, DME distance, INM from a geographical point, vertical, visual or various combinations running together etc.
Depends on your altitude but easiest rule of thumb is 10nm prior to the CTA step applicable for your height!
D Tower in the first instance if youre not sure and they can advise you if there is more appropriate frequency i.e. If radar coverage exist to the top of class D then the sector folks might be administering A045 and above and therefore their frequency might be more appropriate.
That’s one of the ridiculous things with this E stuff is that each D tower has a different set of operating norms dependant on RADAR, INST APP heights etc.
How any pilot in E is suppose to know if the are being monitored on RADAR (Centres) as traffic or NOT (Tower E) is beyond me, thus better to ask if you are not sure.
If other ATC's from Centres or D towers with low-level E airspace have any thoughts on this I would appreciate your inputs?
Hope the trip goes well!
Cap