Had a flight using a SID with multiple altitude constraints programmed in FMS. Aircraft did not level at constraints, but just blew through to the intermediate altitude.

I believe I followed all the  steps to engage VNAV properly according to WT instructions.  Is not this functioning ?

Dave Hinson

I talked to the dev about this on discord. He said that airplane will on respect at or above restrictions (no speed obviously) but it doesn’t work very well. One of the devs is a pilot on the CJ4 and said they never use VNAV on departures anyway just VS and FLCH so that’d how I’ve been trying to fly it.

 

Your best bet would be to join their discord, they’re very quick to answer any questions, show progress updates etc.

Thanks.  Good to know it was not me🙂.

Dave

2 hours ago, DaveH said:

Had a flight using a SID with multiple altitude constraints programmed in FMS. Aircraft did not level at constraints, but just blew through to the intermediate altitude.

I believe I followed all the  steps to engage VNAV properly according to WT instructions.  Is not this functioning ?

Dave Hinson

VNAV in climb is fairly limited; unlike some airliners, the PL21 does not calculate or follow a climb path. The only capability for climb is to stop the climb for AT or AT/BELOW constraints. Above constraints are ignored by VNAV on a climb. Practically this means that if you have a departure procedure with one or more below constraint values, then VNAV, if enabled, should limit the climb to those altitudes until you've passed each constraint and should automatically resume your climb, in FLC mode, after each Below constraint is passed. It will resume at the speed set in the VNAV Climb page. The pilot still has to manually push the throttles back to CL detent when FLC mode is set for it to work.

It is also important to note that the FMS will distinguish between the climb and descent by looking at the segment of the flight plan - if the constraint exists in the departure segment (a waypoint added by a departure procedure added through the DEP/ARR page). No climb constraints other than those in the departure segment will be treated this way. So, for example, if you specified only your departure airport, then manually added waypoints after that, none of them would be treated as climb constraints and they'll be ignored by VNAV.

VNAV for climb is really only meant to provide an extra protection for the pilot for charted constraints if the pilot makes a mistake with the preselector. The reason this is rarely used is that no pilot in the real world would likely ever set their preselector above the altitude they're cleared too or above a charted constraint. It is just counter to training to "trust" automation instead of simply setting the preselector to the cleared/charted constraint altitude.

All that said, it should work as described and I've tested it pretty extensively, as have our QA testers, so if you're finding it is not halting your climb for AT/BELOW constraints in the departure procedure, please submit a bug report because that's incorrect.

Just to double check - please confirm you're on v0.10.2.

Thanks!

Usually when you take off you set the altitude so it could be either the first altitude in the SID or the first altitude ATC assigned you most of the time ATC will take you out of the airspace..

So VNAV is more for STAR and Arrivals..

Yes, I have v0.10.2, and I followed all the steps in the WT documentation.

Dave

I believe I may have missed a step in my DEP procedure - I had not selected either a FLC or VS mode.

Dave

P.S. And another problem - tried my first VATSIM flight in the CJ4 yesterday.  When ordered to line up and wait on a runway, my Comm radio seemed to have suddenly changed freqs, and I caused a big problem because I was waiting to get TO clearance from Tower and caused several planes to go-around 🤥  Was wanting to go to cj4 page on Discord, but could not post question because I had no "Claimed my Account", although I tried several times.  Any help on either of these problems ?

Dave

4 hours ago, DaveH said:

I believe I may have missed a step in my DEP procedure - I had not selected either a FLC or VS mode.

Dave

P.S. And another problem - tried my first VATSIM flight in the CJ4 yesterday.  When ordered to line up and wait on a runway, my Comm radio seemed to have suddenly changed freqs, and I caused a big problem because I was waiting to get TO clearance from Tower and caused several planes to go-around 🤥  Was wanting to go to cj4 page on Discord, but could not post question because I had no "Claimed my Account", although I tried several times.  Any help on either of these problems ?

Dave

likely have FO/AI in settings running comms. when climbing use FLC.

Thanks for the reply.  Can you please explain "FO/AI in settings running comms" ?  I have searched for this setting but don't think I have found it.

Dave Hinson

 

I think I have found your solution.  "Delegate AI to First Officer".

Thanks