VNAV into Approach

[EricJ]

11 hours ago, PeteMc said:

Oh, I get being a different Co/Division.  That doesn't bother me at all for a company that size.  But they have NO coordination.  There should be a HQ department that keeps track of what they're all doing and what they're all looking to release in the next 12-24 months.  Other than Patches for BUGS, it's not like they develop the new features in a week.  (Not talking writing the code, but actually the planning and research.)  So when they see something for the 600 that would work for the 500, then they let them know for continuity.  Same with Experimental vs. Certified....  curious if there's anything the Exp. versions can do that the Cert. versions could benefit by?  That would be another perfect example of lack of coordination.  Right now we Users will be the only way the Cert. crowd will hear about a great Feature Request.  That's pretty bad IMHO.

Product integration planning and coordination and verification all costs a lot of time and money, and can also add a lot to a program schedule in delays.   None of those are liked by managers, especially if they're not a requirement.    Reducing cost and time to market is just better business, sadly.

[PeteMc]

1 hour ago, EricJ said:

Product integration planning and coordination and verification all costs a lot of time and money, and can also add a lot to a program schedule in delays.

Well... I'm not totally disagreeing in some cases.

What do you think it cost them to re-engineer both the GTN Xi and the GNX375/GNC355/GPS175 lines so they now all can talk to each other vs. designing them to do that in the beginning???  I know what you're saying, but so many times companies have had to spend SO much more because of short sightedness.  The 500 vs 600 autopilot also have some of the same issues with approaches that they're now having to correct. 

[Tim-37419]

On 4/19/2023 at 6:08 AM, ArtVandelay said:

My most common mistake is forgetting to set the altitude preselect.

I’ve created a laminated checklist for autopilot functions.

@ArtVandelayI've been reading this old thread it has a lot of great information. Would you mind sharing your checklist with me?

[ArtVandelay]

[mention=11849]ArtVandelay[/mention]I've been reading this old thread it has a lot of great information. Would you mind sharing your checklist with me?

Go to your AFMS, I just copied all the checklists from there;

[Marc_B]

Can't remember if I posted this or not, so circling back around to my original post trying to tease out VNAV power mgmt best practice.

RE: flying an Enhanced VNAV approach descent and handing power settings so that I can 1) descend with speed as long as possible, but 2) still slow down to gear down speed at least by the FAF but ideally by the fix prior:

I found that with cruise power settings that I can point the nose down and descend (VNAV default set at 2.5 deg which is somewhere around ~800 FPM depending on my speed) and it takes me ~5 min and ~2.5 nm to level off and simultaneously pull power to reach equilibrium and steady state speed.  With enhanced VNAV it smoothly flies from altitude to FAF where it picks up GP/GS without level off to slow down.  So with a continued descent from altitude down though the approach to the FAF altitude it makes sense to pull back to 18-20" (2400 cruise RPM setting) at a minimum of 10nm before the FAF.  I can take a look at my FPM descent rate and then determine how early I need to slow down.  For a nice smooth approach I can pull power at the IAF to 20" and for my Mooney for standard 3 deg standard descent (gear down/flaps up): 20" ~115kts, 18" ~105kts, 15" ~95 kts.  YMMV.

[midlifeflyer]

59 minutes ago, Marc_B said:

Can't remember if I posted this or not, so circling back around to my original post trying to tease out VNAV power mgmt best practice.

RE: flying an Enhanced VNAV approach descent and handing power settings so that I can 1) descend with speed as long as possible, but 2) still slow down to gear down speed at least by the FAF but ideally by the fix prior:

I found that with cruise power settings that I can point the nose down and descend (VNAV default set at 2.5 deg which is somewhere around ~800 FPM depending on my speed) and it takes me ~5 min and ~2.5 nm to level off and simultaneously pull power to reach equilibrium and steady state speed.  With enhanced VNAV it smoothly flies from altitude to FAF where it picks up GP/GS without level off to slow down.  So with a continued descent from altitude down though the approach to the FAF altitude it makes sense to pull back to 18-20" (2400 cruise RPM setting) at a minimum of 10nm before the FAF.  I can take a look at my FPM descent rate and then determine how early I need to slow down.  For a nice smooth approach I can pull power at the IAF to 20" and for my Mooney for standard 3 deg standard descent (gear down/flaps up): 20" ~115kts, 18" ~105kts, 15" ~95 kts.  YMMV.

Sounds good to me. Unless there’s a reason to keep up speed to the FAF, slow to approach speed. The one issue I can see is that enhanced VNAV is a calculated descent based on groundspeed at the time of the calculation.  That can change in the course of the descent, which will make your vertical profile different. Simple example, you are flying level at 160 GS. It calculates a TOD, You start down and don’t reduce power so you are now at 175. It recalculates a rate. If it’s higher than your default limit, it won’t make it down.