Good guess, but nope. The only indicator of TCN would be if the Julian date on the procedure matched a TCN cycle.
It appears that the diagonal black lines designate those procedures specifically authorized (and restricted to) military aircraft. (
source)
Nope, that’s not it. In the US you’ll only find them at military airfields. But also take a look also at ENAME volume 7
. Three airports in Turkey (Annan Menderes, Antayla, and Dalaman) have them. (I don’t have any other volumes lying around here, but there’s definitely a lot more)
Any other guesses? I’ll give the answer shortly, but don’t expect it to make sense.
I think I’ve only seen them on high plates...off the top of my head. Not sure if they denote high plates or if there’s a deeper meaning.
This is the closest to the right answer.