It should not be thus restricted.
For example this FPP routing LYBE-EGKB validates
DCT SMI M19 GRZ L604 SULUS L984 BOMBI Z75 NOKDI Z104 GESLO N852 LNO L607 GILOM M624 NIK L179 SASKI L608 LOGAN DCT
FL140
It’s obvious to all that one has to descend eventually…
The minimum level should just be a minimum enroute level.
The minimum level should just be a minimum enroute level.
Now define exactly, with mathematical precision, what enroute is.
I bet you can’t.
Yes, given the constraints you gave it, it’s pretty much unsolvable. Setting min FL to 250 means all SID and STAR segments (or DCT’s serving as airport connections) need to be at or above FL250. I think we should get rid of the min FL setting.
If you set this to FL40, you get a pretty similar route to RR, except with a more realistic climb/descent profile.
OK I think I understand now. So if I leave the min alt really low, will the Autorouter try to find me the highest level that can be validated?
This operates very differently from the RR min alt.
Now define exactly, with mathematical precision, what enroute is.
One would assume that, post takeoff, you climb at the declared climb perf (as per the defined aircraft perf).
The min enroute level is the level you reach after you have exhausted that climb.
The gotcha is that Eurocontrol are also checking your proposed route against its own climb perf model… and they won’t validate the FP unless you can reach the waypoint at which you step up to the cruise level, in time.
I suspect that most people doing their own climb perf models in the router will be a lot less aggressive than Eurocontrol’s model. For example, Eurocontrol’s model is going to assume Vx or Vy all the way up, but nobody with a brain is actually going to fly like that. Eurocontrol’s climb perf model is aggressive which is why one rarely hits that limitation.
But the solution ought to lie in simply specifying the cruise level to be reached a bit later. For example if routing EGKA SFD LYD … for FL100, if FL100 cannot be reached at SFD (probably can’t) but can be reached at LYD (definitely can) then one would do SFD/N0100F040 LYD/N0140F100 …
One would assume that, post takeoff, you climb at the declared climb perf. The min enroute level is the level you reach after you have exhausted that climb.
That simple model often does not work in Europe, especially in southern UK. For example, you’re held at FL80 within the confines of EGTT. So you’ll often have intermediate level offs.
Just a quick heads up that we have made some changes to the altitude model.
First of all, the option to select a “minimum flight level” has been removed. This option was doing too much harm and it was not used in the way it was supposed to be. If you set FL100 because you want to “fly at FL100 or higher” then the router was unable to find a route if there was the need to get to FL100 via a lower level (good example: departing from Biggin Hill which requires the first enroute leg to be at FL040). Too often, changing this field made it an impossible job for the router.
At the same time, we have improved the “preferred level” functionality. Previously, the preference was only weakly enforced, now we push a lot harder. If you end up getting a route which is too low for your taste, do it again with a preferred level. Internally we treat a leg that is one flight level off the preferred one as 20% longer. It’s exponential so 2 flight levels off would be 44% etc.
I hope this will benefit the users overall. We will keep observing and possibly adjusting the metrics.
Just a quick heads up that we have made some changes to the altitude model.
I don’t know … for my previous example (see above: EDDS to EDVE) it now calculates a route that passes the validation. But what a route, some kind of sightseeing tour of southern Germany:
EDDS N0429F050 DKB3H DKB Z818 ELVAG/N0429F260 Y161 RIXED/N0429F280 Y161 DODIL/N0429F290 Y161 REDVO Y161 RIDAR Y161 LELTA Y161 MAH UM726 BESNI UM726 ERNAS UM726 UPALA UL610 INBED UL610 LOHRE UN851 ARNIX UN851 FUL UN851 MASEK UN851 KEMAD UL190 ELNAT ELNAT2B EDVE
Validation:
NO ERRORS
[image link fixed]
I get this one
EDDS2127 -N0316F240 OKIBA3B OKIBA N851 ROLSO N851 RIMKI N851 OSBIT P605 OBISI P605 FULNO P605 KEMAD P605 ELNAT ELNAT2B -EDVE0051
with 5% overhead at FL240. However, I discovered exactly the problem you mentioned earlier. The route is incorrectly displayed. Unfortunately my mouse batteries are empty and I don’t have any spare batteries so debugging will have to wait 
Is anyone else getting “Error: stopped by user” when trying to find a route?
(I’ve opened a ticket and hope you have a couple of fresh batteries by now Achimha 
)
Edit: It’s fixed, I managed to mess up my aircraft profile.. thanks Achimha
Yes, a climb rate of 0fpm at 4600ft for a C172 is probably how it feels like but the POH gives different numbers
