I have been able to consistently land using VNAV with the C172 and C208, but I am not too sure what I am doing with the Bonanza. Like most things in MSFS 2024 I suspect I am just not fully understanding how this thing works. For reference I was using an RNAV approach.

With the C172 and C208 I am able to get VPTH working so that from the time I activate the approach right up to threshold, the Auto Pilot manages the vertical descent, lining me up perfectly with the runway and capturing the Glide Path/Slope. With the Black Square Bonanza, this baby is just a little different. For reference I am using the TDS unit, and it has a VNV option under utilities, which I think I use for reference when setting VS? I am actually getting the GS but it doesn't appear the manage the descent without me using VS.

In any case, here are my questions...

1. Do I need to set and manage the VS for each leg of the approach, or will this thing manage the descent on its own using the FPL altitudes set for the approach? 

2. Do I use the VNV VS data in the TDS as a reference to set the VS manually?

I really like this plane but just not sure what I should be expecting after being spoiled rotten from the Cessnas.

Thanks guys!

Edited January 29Jan 29 by RobJC

22 minutes ago, RobJC said:

1. Do I need to set and manage the VS for each leg of the approach, or will this thing manage the descent on its own using the FPL altitudes set for the approach? 

2. Do I use the VNV VS data in the TDS as a reference to set the VS manually?

You have to manage the vertical profile manually... using the approach chart as a reference.  The TDS unit has the charts built in.

Once you are on final, and the GTN indicates LPV, you can switch the autopilot to APR mode and capture the glidepath.

This BK autopilot does not do VNAV..   I am surprised you got the Cessnas to do anything more.. in real life, their autopilots would not be any more capable..   As best I know, you need a Garmin autopilot, coupled with the Garmin GTN to do VNAV. 

The key thing to focus on is the target altitude for the glidepath intercept.  Unless you have ATC directing you, you should be able to manage your vertical descent according to your preferences... this is not an airliner 😉  

Might be fun to read the actual autopilot manual.. www.bendixking.com/content/dam/bendixking/en/documents/downloads/006-18035-0000_1-KFC-225-KI-525A-Pilot-s-Guide.pdf

Edited January 29Jan 29 by Bert Pieke

I manage VNAV by myself using combination of VS/IAS/Pitch  descent depending on circumstances. TDS provide  a "banana" that shows approximate point of target altitude intersection - that gives me idea on how to manage vertical descent rate . The only time TDS managing vertical guidance is on LPV approach with APP engage below GP.

1 hour ago, Bert Pieke said:

You have to manage the vertical profile manually... using the approach chart as a reference.  The TDS unit has the charts built in.

Once you are on final, and the GTN indicates LPV, you can switch the autopilot to APR mode and capture the glidepath.

This BK autopilot does not do VNAV..   I am surprised you got the Cessnas to do anything more.. in real life, their autopilots would not be any more capable..   As best I know, you need a Garmin autopilot, coupled with the Garmin GTN to do VNAV. 

Thanks Bert! Okay that helps. Yeah, the Caravan had the G1000 and the 172 was using TDS and a KAP 140 (I believe) and both did really smooth VNAV. I was able to capture the GS, but I just was a bit lost as to how to know if my descent was the right angle or not. The chart shows 3.04 degrees, (KCOS RWY 31 RNAV) so I need to figure out how to match that. The runway lights were showing 4 red so I knew I was too low, but I was thinking maybe another gauge would show me if I was high or low so I could manage it? Good stuff regardless! 

54 minutes ago, sd_flyer said:

I manage VNAV by myself using combination of VS/IAS/Pitch  descent depending on circumstances. TDS provide  a "banana" that shows approximate point of target altitude intersection - that gives me idea on how to manage vertical descent rate . The only time TDS managing vertical guidance is on LPV approach with APP engage below GP.

Awesome. I will look for that on the next test flight. Thank you!

38 minutes ago, RobJC said:

Thanks Bert! Okay that helps. Yeah, the Caravan had the G1000 and the 172 was using TDS and a KAP 140 (I believe) and both did really smooth VNAV. I was able to capture the GS, but I just was a bit lost as to how to know if my descent was the right angle or not. The chart shows 3.04 degrees, (KCOS RWY 31 RNAV) so I need to figure out how to match that. The runway lights were showing 4 red so I knew I was too low, but I was thinking maybe another gauge would show me if I was high or low so I could manage it? Good stuff regardless! 

OK, the G1000 is all Garmin, so that makes sense.  KAP140...?  

The Bonanza Pro actually has a KFC150 autopilot:  www.bendixking.com/content/dam/bendixking/en/documents/downloads/006-08377-0001_1-kap-150-ki-525a-pilot-s-guide.pdf

Once you are stable on final (ALT mode) and ready to capture the autopilot, the APR setting on the autopilot should get you to the runway... You, however, need to manage the speed!  

Until glidepath capture, you are indeed below the glideslope, so four red would be technically correct..

Edited January 29Jan 29 by Bert Pieke

35 minutes ago, RobJC said:

The chart shows 3.04 degrees, (KCOS RWY 31 RNAV) so I need to figure out how to match that.

The 3.04 degrees on the approach plate is the glidepath angle you'll get after glidepath intercept - which on the approach you're discussing should occur at JATOL if you're at 7800' when reaching this fix.  Here is where you should intercept the glidepath from below.  At this point, and assuming APR mode is selected on the AP, you now WILL have vertical guidance for the AP.  And if manually flying, you'll simply follow the GS indicator on the HSI, adjusting power and pitch as necessary to maintain glidepath and airspeed.

For the stepdowns on this approach prior to glidepath intercept, simply VS down at an appropriate rate.  So, what's "appropriate"?  As @sd_flyer notes, the GTN's "banana" can be used to see if the vertical speed you've selected will get you to the next fix at the altitude you've pre-selected.  You can also use simple math, looking at time to next waypoint and figuring what kind of descent you'll need to arrive prior to the fix. 

For example, on the KCOS RWY 31 RNAV approach, suppose I arrive at ZENER at 9400' and now want to descend to 8600' before NUTVE.  If I note that my GTN says I'll arrive at NUTVE in say a minute and thirty seconds I can see that I'll easily get to my next stepdown altitude using a VS of 500'/min with time to spare.  No need to be super precise in your calculation - you can do quick approximations and then use the "banana" to see if things will work out.

As noted, this is not an airliner flying with an FMS.  This kind of functionality matches what you'd actually have with this plane and these avionics and is part of the fun in flying a plane like this.  But honestly, for even more fun forget the AP altogether and fly the approach by hand as you'd have to if training for an instrument rating.  Letting the AP do all the work takes some of the fun out of things!

 

Scott

Edited January 29Jan 29 by tttocs

You only need a couple of rules of thumb, or "pearls of wisdom" for a 3deg glidepath:

Target Rod = 5 x ground speed (in fpm) e.g. 100kts GS = 500fpm

A 3deg glidepath will bring you down at around 320 feet/nm e.g. if you have 2nm to your next fix you should be 640ft (round to 600ft) above it.

 

Easy

 

One final note on the vertical path indicated by VASI or PAPI lights vs glideslope/glidepath - be aware that path angles indicated don't always match, both in the sim and in real life.

 

Scott

Awesome guys. Thank you! 

3 hours ago, tttocs said:

The 3.04 degrees on the approach plate is the glidepath angle you'll get after glidepath intercept - which on the approach you're discussing should occur at JATOL if you're at 7800' when reaching this fix.  Here is where you should intercept the glidepath from below.  At this point, and assuming APR mode is selected on the AP, you now WILL have vertical guidance for the AP.  And if manually flying, you'll simply follow the GS indicator on the HSI, adjusting power and pitch as necessary to maintain glidepath and airspeed.

For the stepdowns on this approach prior to glidepath intercept, simply VS down at an appropriate rate.  So, what's "appropriate"?  As @sd_flyer notes, the GTN's "banana" can be used to see if the vertical speed you've selected will get you to the next fix at the altitude you've pre-selected.  You can also use simple math, looking at time to next waypoint and figuring what kind of descent you'll need to arrive prior to the fix. 

For example, on the KCOS RWY 31 RNAV approach, suppose I arrive at ZENER at 9400' and now want to descend to 8600' before NUTVE.  If I note that my GTN says I'll arrive at NUTVE in say a minute and thirty seconds I can see that I'll easily get to my next stepdown altitude using a VS of 500'/min with time to spare.  No need to be super precise in your calculation - you can do quick approximations and then use the "banana" to see if things will work out.

As noted, this is not an airliner flying with an FMS.  This kind of functionality matches what you'd actually have with this plane and these avionics and is part of the fun in flying a plane like this.  But honestly, for even more fun forget the AP altogether and fly the approach by hand as you'd have to if training for an instrument rating.  Letting the AP do all the work takes some of the fun out of things!

 

Scott

Thanks Scott! I am not getting vertical guidance so i need to sort this part out. Definitely will do some hand flying as well. Good point! 

1 hour ago, RobJC said:

Thanks Scott! I am not getting vertical guidance so i need to sort this part out. Definitely will do some hand flying as well. Good point! 

Just so we're on the same page, forget about VNAV, as this is not a VNAV "thing".  This is about Glideslope (ILS) or Glidepath (RNAV with vertical guidance) capture.

So... You're not getting vertical guidance at and after glideslope/glidepath intercept?  Going back to your approach at KCOS, are you established at 7800' at JATOL, and in APR mode on the autopilot?  In order to capture the glidepath, you must intercept it from below and must be in APR mode.  If either of these things are untrue, you won't capture. 

Pls try this exaggerated method the next time you fly this approach to be sure you're getting where you need to be.  At NUTVE, activate APR mode and VS aggressively down to 7800' to make sure you are level at this altitude well before you reach JATOL.  What the chart is telling you is that you can be at 7800' any time after NUTVE, so it's OK to do this while you figure things out.  If you're not getting down soon enough, you risk staying above the glidepath so don't be afraid to descend quickly to the charted altitude while figuring out how this works.  You can do this with more finesse after you've seen how it works out for you. 

If you're doing this correctly, as you approach JATOL you should see the GS indicators on your HSI slowly coming down to the center at, or near JATOL.  If you reach this point too high, the GS/GP will already be below you and you won't capture. 

And again, before GS capture (in this case at or near JATOL), any descents are all up to you.

Let me know how this works for you,

 

Scott

 

Thanks again Scott. I will test and report back! 

That was it Scott! It caught the GS and brought me right down. Thank you sir!