The section between VAGAB and GAPLA is forced to FL240. What I believe should happen is that SB sees my cruising level and detects that T170 also has a high-level route that allows (in my particular case) continued flight at FL360.
It’s very typical of German airports to have these kind of restrictions on airways for arriving/departing aircraft. You’ll almost always be below FL245 at VAGAB due to the structure of the airspace, influenced by KERAX with an “above FL110” restriction.
The reason why it’s limiting you to FL240 there is because SimBrief’s aircraft performance profile does not follow Eurocontrol’s. IFPS will allow you to not file a step descent there, as it assumes you’re already descending for Frankfurt. Being at cruise at VAGAB would leave you quite high!
“T170 between VAGAB and GALPA is max FL245.”
Ref: AIP IFR Germany, ENR 3.2-T-9.
RAD restriction ED2191 restricts usage of T170:
“ONLY AVBL FOR TFC ARR (FRANKFURT_GROUP, FRANKFURT_YZ_GROUP)”
in order to “segregate arriving traffic from transit traffic”, which applies in your case (OKKK-EDDF)
Ok, thanks for your replies. The reason I asked was threefold:
The route T170 itself as mentioned before is both a low and a high-altitude airway. This of course does not take Eurocontrol restrictions into account.
I work for an airline and as such have access to the repository of OFP’s. Including the one they filed that day (Jan 26th). This is the ATC route string.
As you can see here, they do not have a restriction of FL245 for their arrival into EDDF. It shows FL380 at KODAV all the way to Top of Descent.
After adding the route string without any T170 route restrictions, and as taken from the route above (My flight that day left OKKK, so I simply copied my SB ATC string, pasted it into the EuroControl NoP page, but made sure the route was the one above, which I made sure was identical arriving into EDDF as you can see.) NoP returned “No errors” on my string without the any maximum FL limits over e.g. VAGAB.
So, both the route properties itself and Eurocontrol Network Operations Portal agreed that a maximum FL restriction into EDDF was not necessary.
High/Low altitude airways do not really exist anymore in (RNAV-5) Europe in the traditional [USA below/above FL180] sense; only airspace is designated this way now (and even then split into 3 or more!).
The German IFR AIP-ENR-3 section only distinguishes between “Konventionelle Navigationsstrecken” [Conventional Navigation Routes - which don’t exist anymore], and “RNAV-Strecken” [RNAV Routes].
ENR 3.2-1 Note 8 defines ATS routes commencing with a T as “indicating transitioning from the enroute phase to terminal operation”.
I have access to the same systems as you through work, and I can see the OFPs for most flights from that direction route …DCT AKINI T161 DEBHI.
However the winds aloft that day [and knowing Germany, probable tactical off-load restrictions in EDUU_DON/EDDM_ALB] meant that the flight routed further north through LKAA via RAPET.
As I explained before, and I will repeat myself again, the reason why it’s limiting you to FL240 at VAGAB is because SimBrief’s aircraft performance profile does not strictly match Eurocontrol’s.
IFPS [Eurocontrol] already assumes you’re descending for EDDF before you hit VAGAB, as Eurocontrol internally uses an averaged/more realistic system called BADA [Base of aircraft data] (which is only accessible under licence, but accessible publicly on a small scale via that link to the APD I posted), and has all of the standing agreements for levels between sectors, STAR level and speed restrictions, etc, input into this giant supercomputer.
Some flight planning software, even in real-life, incorrectly forces aircraft down to FL240 or lower on restrictions like this, and some level restrictions are timed.
It all depends on what IFPS validates on the day, and SimBrief isn’t flexible enough for that.
The issue boils down to:
Your aircraft’s performance is beating the SimBrief descent predictions for your A/C type and its calculated TOD, whereas it’s matching (or less) than the Eurocontrol ones.
So that’s why your FPL has no error when validated via IFPS, but SimBrief drops you down because the A/C model is not the same as real-life.
To add to this, every airway restriction is bulk input/removed into SimBrief with not much manual validation iirc.
I personally force SimBrief to manually use the levels I specify that have IFPS-validated
