I may not be doing something right but I have very limited success with the X using VNAV, SIDs & STARs, SIDs only. So, off to YouTube, The Flight Level posted a VNAV Tutorial, a 40 minute flight from Las Vegas to Phoenix. I’m pretty confident that I’ve copied every aspect of the video, but my VNAV simply doesn’t respond as shown. Is there a known bug with the VNAV or am I alone here? TIA!
p.s.
I still haven’t solved the cabin pressure problem. Most of the time I get FMS cabin pressure alerts and warnings. I am losing passengers to asphyxia every flight…
did you make sure there were no discontinuity’s or (Vectors) as a waypoint in the flight plan? If there is no altitude restriction before a discontinuity or vector waypoint in the flight plan it won’t see the ones after that.
can you post a picture of your instrument panel in cruise with the cabin altitude warning? it sounds like something isn’t set correctly
I cleared the discos, I’ll have to check on the Altitude Restrictions prior to the Discos, not sure at the moment. VNAV seems to disregard the altitude and speed restrictions in the SID and STAR, follows VALT. I’m taking a little break here to let some of my hair grow back (after pulling it out, LOL). I’ll post cabin pics of the pressure control area in a bit.
The settings in there are Rate: MAX, all others in that section are NORM. I adjust the altimeter just above to cruising altitude, using the ‘A’ control. The section to the right, Left and Right ENG BLD AIR set to HP/LP, ISOL VALVE On, Cockpit and Cabin PACs ON.
Thanks for checking!
Here is my pressurization panel in cruise at FL390
Hi @trashmon49 ,
Make sure you set the flight altitude in the pressurization controller by turning the knob labeled “A” as in the picture above by @wcc96387 before engine start. In his case the highest FL was 390, therefore he set it to 39 since the outer scale of the gage is calibrated to AIRCRAFT ALT x 1000 FT. (=39000 ft)
The inner scale will then give you the corresponding CABIN ALT x 1000FT. (In this case about 5.1 which equals 5100 ft cabin altitude)
Same, with the exception of the RATE control which I have set at MAX.
For the VNAV, make sure the FMS is calculating a Top Of Descent (TOD). Hit PROG then NEXT and it should give you a distance in miles to TOD, if it doesn’t then there’s no altitude constraints set in your flight plan for it to follow.
once you have the TOD displayed in the PROG page, set your desired altitude for the autopilot (I usually just set the lowest altitude in my flight plan or the IAF for an approach. I do this about 40nm from the TOD, and about 10nm before I hit the VNAV button on the autopilot. on the top of the PFD you should see VALT. then at the TOD it should start your descent.
Then set your cabin altitude (inside numbers) to your landing airport altitude in the pressurization panel. the rate knob is fine at about a 700fpm climb or descent, no need to max it out
Thanks for the reply! I have the flight altitude set to my cruise altitude. I’m not certain that I set it before engine start but I’ll make certain to do that next flight and see if there is a difference in pressurization behavior…
In the checklist the pressurization isn’t mentioned until the before taxi checklist, so setting it before start shouldn’t make a difference.
Hi,
I believe it should work either way. Just make sure that it is set before taking off.
Here’s a quick and dirty video of the top of my descent into KMIA just now
I just had an issue with the Citation X with a 3rd party livery… this one livery I cannot get the IRS to align… changed liveries and it works fine, so if you’re using a 3rd party livery try changing that and trying a flight
Thanks! I’ll check those things, never tried the PROG to look at TOD. Frankly, this is the first FMS I’ve really gotten into and I had no idea what the PROG function was. I understand how to enter speed/altitude constraints, so I’ll verify (pretty sure the constraints match the tutorial I’ve been following).
Thanks, using stock liveries, X version with winglets (can’t fathom how winglets could make a difference…
)
Well…
Success!! Not one caution or warning about cabin pressure the entire flight. Dialed down the altitude to arrival airport and no issues. The only thing different that I can see is that I left the RATE at NORM instead of MAX. I also noted a caution when cockpit and cabin PACs were on, so I turned them off and reset them on when I was airborne. Someday when I need to beat myself up, I’ll try it again with RATE on MAX, but that’s not happening anytime soon .
The flight was uneventful with VNAV following the flightplan as advertised. Unfortunately, I landed in Phoenix and had to taxi for many minutes to a remote parking spot. Should have just taken a tubeliner and let the pilots get me there…LOL!
Thanks so much for your help on this, I still don’t understand everything I don’t know about FMS, but I’m slow…
Tim
