Cirrus SR-22 and VNV

[Boeing_Driver 76]

I've been flying this plane a lately and trying to get a better understanding of its capabilities.

So far as I can tell, this plane is different from a lot of other planes in that you don't use the APR button when on an RNAV approach. Rather, one uses VNV for the entire approach. 

 

Is that correct? The APR button is only used for ILS approaches?

[Jeffg817 26]

The APPr button should be used when on any approach when the CDI is greater than 1 dot arms the approach mode in White and than when activated goes green needles.The definition out of the Cirrus FOM is Approach mode acquires and tracks the selected navigation source (GPS,VOR or LOC)  depending on loaded approach.

Jeffg

[ark 1,291]

1 hour ago, Boeing_Driver said:

I've been flying this plane a lately and trying to get a better understanding of its capabilities.

So far as I can tell, this plane is different from a lot of other planes in that you don't use the APR button when on an RNAV approach. Rather, one uses VNV for the entire approach. 

 

Is that correct? The APR button is only used for ILS approaches?

No, my understanding is VNV mode will terminate at the FAF and you still need to use APR mode.

Al

Edited December 13, 2023 by ark

[fsiscool 251]

19 minutes ago, Jeffg817 said:

(GPS,VOR or LOC)

or visual approach, a feature which I admire as it gives you an instrument approach on any runway on this earth.

[Boeing_Driver 76]

16 minutes ago, ark said:

No, my understanding is VNV mode will terminate at the FAF and you still need to use APR mode.

Al

So to be clear, is it critical when to press APR? can it be done prior to the FAF?

[ryanbatc 12,859]

You still use approach mode during an ILS or RNAV(GPS) approach with vertical guidance.  For rnav approach with LNAV mins you can use APR mode but you need to meet the altitude constraints on the chart... So irl it's typical to descend with VS speed mode (and NAV) while bugging the step down altitudes on the approach plate.

Irl I press APR when I'm cleared for the approach.  But in the sim...I'd say anytime before the final approach fix should work....as long as you're at or below the glide path.

Edited December 13, 2023 by ryanbatc

[ark 1,291]

2 hours ago, Boeing_Driver said:

So to be clear, is it critical when to press APR? can it be done prior to the FAF?

Yes, as Ryan said, definitely before the FAF.  Gemerally in the sim arming the approach a couple miles before the IAF usually works out well. The less buttons you have to push as you near the FAF the better since that is a good time to remind yourself of at least the initial details of the missed approach procedure. At some point during the approach you will want to get things set for a possible missed approach -- dial in the target missed approach altitude and perhaps preset the heading bug, etc.

Al

Edited December 13, 2023 by ark

[JYW 2,984]

If you look carefully at the top of the VNAV scale, when it appears on the PFD;  if there is a small 'v' it's a VNAV profile, if it turns to a 'g' (for GP or glide path) you'd hit APPR as this is a glide path profile. 

[Boeing_Driver 76]

1 hour ago, ark said:

Yes, as Ryan said, definitely before the FAF.  Gemerally in the sim arming the approach a couple miles before the IAF usually works out well. The less buttons you have to push as you near the FAF the better since that is a good time to remind yourself of at least the initial details of the missed approach procedure. At some point during the approach you will want to get things set for a possible missed approach -- dial in the target missed approach altitude and perhaps preset the heading bug, etc.

Al

When is it possible to reset the Altitude (to the Missed Approach altitude) when on an VNAV path? After the GP is captured? Or after the MAP?

[MattNischan 3,778]

47 minutes ago, Boeing_Driver said:

When is it possible to reset the Altitude (to the Missed Approach altitude) when on an VNAV path? After the GP is captured? Or after the MAP?

The autopilot will always capture the alt preselector while your active AP mode is VNAV. The autopilot, conversely, will always ignore the alt preselector once in either GS or GP.