VNAV

[dirmer3]

I cant seem to get the aircraft to descend on the arrival. I'm following totos video and I have the aircraft in vAlt, APPR, LNV1 but it has white letters that days "NO APPR" what am I doing wrong?

Edited January 12, 2022 by dirmer3

[Rastuasi]

Did you actually enter and exc the approach in the FMS? I had that show up last night, I merely went back in to the DEP/ARR page and redid it and it magically worked. Also, you do not want to really be hitting that APPR button till you're on the last bit right before the approach starts.

[dirmer3]

34 minutes ago, Rastuasi said:

Did you actually enter and exc the approach in the FMS? I had that show up last night, I merely went back in to the DEP/ARR page and redid it and it magically worked. Also, you do not want to really be hitting that APPR button till you're on the last bit right before the approach starts.

Yeah, everything was executed fine. I'll try again later and see if it's any different.

How do you have the autopilot configured so that it automatically descends at TOD at a rate which matches the altitude constrains on the STAR?

[Rastuasi]

When I hear the gong for TOD, usually 1 minute out, I simply activate VNAV, FLC, and set the Altitude to the base of the descent (where the approach alt starts). Once you do that, then if ATS is on and profile is setup for approach, it will throttle back to M.72 (default) and start the descent.

[Rastuasi]

As a side note, I did try to set up the descent early, but the moment I set VNAV, FLC, and alt, she starts descending. I'm not sure how or if it is allowed, one can set up the descent and let the system start it at the actual TOD.

[JC_YYZ]

45 minutes ago, Rastuasi said:

As a side note, I did try to set up the descent early, but the moment I set VNAV, FLC, and alt, she starts descending. I'm not sure how or if it is allowed, one can set up the descent and let the system start it at the actual TOD.

I am definitely not an expert, but I think hitting FLC will tell the plane to descend immediately. When I setup for VNAV, I simply set the desired altitude that I want to descend to (the plane will honour restrictions, so I usually set it to the base altitude on the final approach if I am offline), leave everything else alone (plane is usually LNAV1, ALTS or similar with ATS on and VANV button activated) and one the plane hits TOD, it begins to descend. Very similar to the 737 behaviour in my experience.

Again, I think the FLC will cause it to descend to the dialed-in ALT immediately.

[Rastuasi]

Interesting, thanks @JC_YYZ I shall have to test that on my next flight. I know my other planes will not do that, you have to either set VS or FLC to get them to start, so that TOD beep is purely informational. However, it should be noted, they also don't start immediately if VNAV is on, they wait for the VNAV lock to kick in (pink circle that comes down from side)

[JC_YYZ]

1 minute ago, Rastuasi said:

Interesting, thanks @JC_YYZ I shall have to test that on my next flight. I know my other planes will not do that, you have to either set VS or FLC to get them to start, so that TOD beep is purely informational. However, it should be noted, they also don't start immediately if VNAV is on, they wait for the VNAV lock to kick in (pink circle that comes down from side)

This plane does that - so usually about a minute out, you get the TOD 'ding' followed by the VPATH notification with the pink VPATH diamond. At the same time, the thrust reduces and the plane pitches down to follow the path (again, honouring any ALT and SPD restrictions). I'm pretty sure you could fly it almost down to the threshold like this, although I don't think it will land itself!

[Rastuasi]

Sweet deal, okay, so I shall have to plan a flight for this evening.. would do it now, but work is a thing. 

[JC_YYZ]

1 minute ago, Rastuasi said:

would do it now, but work is a thing.

That's my biggest problem these days: My day job getting in the way of my hobbies. LOL

[Graeme_77]

VALT will transfer to VPATH when you hit the ToD. If you want to descend now, FLC or VS. Remember VNav is a modifier, not a discrete mode.

When you intercept the target path, in any vnav modified mode (VALT, VFLC, VVS, VPTCH) you’ll go to VPATH and follow the programmed descent.

[EGT]

VNAV button remains lit when valid. All vertical modes become VNAV modes with exception of VPATH which auto-arms at ToD.

FLC = VFLC (follows VNAV profile in either climb or descent)

ALTS = VALTV (respects crossing restrictions regardless of set altitude)

VPATH = auto-armed at ToD and will commence descent if altitude selector is lower that present altitude (double chord sound at path intercept)

Ensure the option (PERF x 2) is set for "ENABLE ADVISORY VNAV". It will draw the vertical diamond on the PFD when the vertical path is near.

Also ensure to "RESUME VNAV SPEED" (PERF x 2) to get it to follow the VNAV speed schedule, otherwise the selected speed takes precedence.

Edited January 14, 2022 by EGT

[leha74ru]

1 hour ago, EGT said:

Also ensure to "RESUME VNAV SPEED" (PERF x 2) to get it to follow the VNAV speed schedule, otherwise the selected speed takes precedence.

how to get back if you clicked and now there is VNAV PLAN SPEED

[EGT]

1 hour ago, leha74ru said:

how to get back if you clicked and now there is VNAV PLAN SPEED

You can only select it. If you select it, FMS VNAV will control the speed.

If you want manual control of speed, just select a different speed with the speed selector knob on the AP control panel.

Edited January 14, 2022 by EGT

[kecm80]

hi Everyone,  isn't the challenger supposed to descend via VPATH with engines at idle? i noticed that N1 is decreasing slowly but for not at idle since TOD. 

FPA not touched, still at -3°

[Pils]

5 hours ago, kecm80 said:

hi Everyone,  isn't the challenger supposed to descend via VPATH with engines at idle? i noticed that N1 is decreasing slowly but for not at idle since TOD. 

FPA not touched, still at -3°

No, it’s not like an Airbus or Boeing. It targets a fixed FPA, respecting constraints otherwise, and that’s it.

[kecm80]

7 hours ago, Pils said:

No, it’s not like an Airbus or Boeing. It targets a fixed FPA, respecting constraints otherwise, and that’s it.

ok thanks, was referring to the cl650 operation reference pdf but in some other documents found on the web there is another way to descend not using VPATH, thanks indeed for your explanation 

[Pils]

I guess this is just a consequence of the ATS being somewhat independent from the FMS due to its “aftermarket” origins on the type.

[Graeme_77]

@kecm80It's just an airplane - it flies on pitch/power like everything else. That chart is only giving you some approximate pitch/power datums to help you fly the aircraft. You can descend using VFLC if you want - that will give you an idle descent and will obey the constraints, but managing the profile will be your responsibility.

[kecm80]

2 hours ago, Graeme_77 said:

@kecm80It's just an airplane - it flies on pitch/power like everything else. That chart is only giving you some approximate pitch/power datums to help you fly the aircraft. You can descend using VFLC if you want - that will give you an idle descent and will obey the constraints, but managing the profile will be your responsibility.

thanks Graeme, i really love this plane and the simulation level it brings to xplane, finding more information isn't easy since every company has it own Sop's.

So you (team) were experiencing a lot of questions from users and 99% of the time is not a figner point to the quality of the CL650 but simply a newbie question. And to be transparent I like to say that dev team should not answer like "the challenger is doing exactly like this" or other answers similar, but taking some time to answer is well appreciated. Appreciated like your YT videos since they're a masterpiece of explanation.  (still waiting the last felis 747 one :P) 

 

thanks

[Graeme_77]

No problem at all. I do understand the complexity - the Challenger is a very rare sim aircraft that does almost everything like the real thing. The resources the development team have had are exceptional.  Newbie questions are totally fine, and that's exactly the point in the forum. Any frustration from forum participants is usually down to when posters phrase questions that read like "Boeing does X so Hot Start Challenger is wrong."  It's a different sort of system, but one by one we'll make sure the sim community are confident ProLine 21 Advanced pilots ;-)

Not being able to do an idle descent is unusual coming from an airliner background, but when you understand the system is designed to be just as useful without autothrust, and the descent angle mode is probably more pilot-friendly anyway it starts to make a lot of sense.

[arrowspace90]

On 1/11/2022 at 6:42 PM, Rastuasi said:

When I hear the gong for TOD, usually 1 minute out, I simply activate VNAV, FLC, and set the Altitude to the base of the descent (where the approach alt starts). Once you do that, then if ATS is on and profile is setup for approach, it will throttle back to M.72 (default) and start the descent.

It shouldn't be necessary to arm both VNAV AND FLC.  FLC will not calculate crossing restrictions.