Take a SID like this, BARPI2K at LJPZ. SID chart

The textual Route description says


Climb on track 315 to 1700 ft; LT to PZ L; overhead PZ L; LT on HDG 295; intercept PZ QDR 325 PZ L to BARPI. Cross PZ L at 3400 ft or above.

Now the navigator in my aircraft can load and fly this procedure perfectly based on GPS along, without ever referring to the ADF which is only installed in the aircraft for compliance reasons.

But what if the PZ locator is NOTAM-ed out of service? Can ATC still assign this SID?

I'm torn on this as on one hand it is a navaid that is part of the procedure, but on the other hand this is is an RNAV SID anyway (it ends at a fix) so they know I'm still capable of navigating to "PZ L" with the exact same accuracy as before.

Approaches are another, much clearer matter, but I could not find anything official on SIDs/STARs.

This example is EASA (Slovenia) by the way, but of course we can discuss national differences if there are any.


1 Answer 1


This is legal in the United States, per AC 90-108. GPS can be used in lieu of NDB or DME in most cases. One of the exceptions is when the procedure is NOTAMed as not authorized. But this applies to the procedure as a whole- if just the navaid is NOTAMed out of service using GPS is still permitted.

A similar idea seems to have been adopted by EASA recently, as seen in this amendment document:

Applications of RNAV substitution include use to [...] navigate to or from a VOR, or NDB, except as lateral guidance in the FAS of an IAP


RNAV substitution for ADF, marker and VOR may be used where airborne and/or ground-based equipment is not available

So, if my reading is correct, this was illegal until very recently but might be legal now. It would be wise to check with someone more familiar with Slovenian law in particular, though.

  • $\begingroup$ That's really interesting, the amendment you linked to is very explicit on the matter, but also as you note it's very recent, good to know. Thank you! $\endgroup$ Commented Jul 30, 2023 at 19:40

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