I’ m having difficulty getting RNAV approaches to work, this after several months of absence from MSFS. I can still do ILS approaches and they’ll get me close to the runway using Glide Path. Now, when I try RNAV GPS approaches I cant seem to get the aircraft to lock onto the Glide Slope and take me down. Using the Beech Bonanza G36 with G1000nxi. Simple Flight plan entered into the Garmin (nearly a straight in approach 30 - 40 NM out), and Approach parameters entered, approach, waypoint scheme, min altitude set to BARO and minimum altitude set to the published plate diagram. Then, approach to ACTIVATE and proceed to depart. Climb to altitude, follow the waypoints to the FAF, press FD APR button. At this point, I may or may not see the magenta diamond on the altitude tape (GS is displayed in white). When, and if, the diamond appears I may be above or below it, I chase it to get it to center it in the altitude tape, but it never locks onto and follows the descent path. I’ve tried approaching significantly below the FAF altitude but still will not grab the path and the diamond still continues falling until I have to hand fly. I’ve watched so many YouTube videos on this topic I’m going cross-eyed and still can’t figure out what I’m doing wrong. Any assistance would be gratefully accepted, thanks in advance.
The rnav following the “glidepath” has not worked from the start so it is not you
It works with the G1000Nxi, and works natively with a small subset of approaches. I wonder whether OP has the same issues with other planes.
I wonder why you need to press FD sequentially before APR. If the AP is on and following LNAV during enroute to the IAF, usually FD is already enabled. And APR is armed before the FAF? The way to tell is the white GS/GP in the Annunciator Scoreboard. That will flash Green and then switch to Steady Green as you capture GS/GP guidance.
If your using a Honeycomb Bravo, make sure your not in vertical speed mode.
I’ve had a difficult time as of late with RNAV approaches in any plane not using the G1000 NXi. With planes using the GNS530 (with or without the PMS50 mod) or using the TDS GTNXi, it’s been rather hit or miss if it captures the vertical component of the RNAV approach or not. Never have any issue with ILS, not do I have issues with RNAV when using the G1000NXi. But it’s almost certain that if I’m in such a plane on an RNAV approach, I’m going to have to manually control my vertical rate as the glide path won’t capture.
Oddly, I used to never have issues with RNAV approaches regardless what plane I flew. This seems to be a rather recent thing for me. Not sure when it started as I’ve been mostly flying the Kodiak since I got it before Christmas, and mostly flying the SR22, Bonanza or CJ4 for IFR flights when not in the Kodiak. I noticed this difficulty with RNAV a couple of weeks back and have since experienced it in pretty much any plane that doesn’t use the G1000 NXi. I suspect the CJ4 is probably ok, but have only done ILS approaches with that, so can’t say for sure.
Same with the Cessna Sky
hawk
Try making a video perhaps?
Specifically which approach are you trying to do? Not all RNAV approaches have vertical guidance; there are several different types. Be sure you’re selecting either an LPV or LNAV+V approach.
There are many diffent sequences and timings of button pushes for RNAV approaches as there are different GPSs.
First, make sure the RNAV approach has vertical guidance by checking the approach chart. Look for “LPV” in the bottom section listing the types of approaches. Not all RNAV approaches have vertical guidance for a glide path.
To capture a glide path, make sure you are at the altitude for the IF. This is where the approach begins. This isn’t 30 to 40 nm from the airport. At this distance the GPS provides the lateral guidance in the flight plan. VNAV can be used for vertical guidance until stating the approach.
The G1000 NXi has an awesome feature to create RNAV approaches with vertical guidance for any airport and runway. Note: these approaches do not provide terrain or obstacle avoidance.
To use this feature, select “PROC” on the flight plan section. Scroll down to “Select Approach” and press Enter. A box selection menu will appear listing all the approaches for the destination airport. Scroll to the bottom and select the Visual approach for the runway you want. Press Enter to select, next select the transition and then scroll through the remaining items to activate. The new flight plan with new waypoints are displayed. Press NAV for the GPS to start flying it.
I use this to practice flying RNAV approaches fine tuning when and where various buttons and actions are performed.
Currently I am practicing approaches with the C208. I’m having problems when configured for landing the AP drops my airspeed below stall and the C208 falls out of the sky….
Also, LittleNavMap has a feature to create an approach and insert into a flight plan, very helpful for practice as well.
Absolutely. I’m attempting LPVs at different airports. Your methods are exactly what I’ve been doing, selecting a transition and following the waypoints into the runway at the prescribed altitudes. I’m selecting APR at the FAF point and altitude to arm the Garmin function, but so far, no joy. The magenta diamond indicator simply passes from above the aircraft to below and is never captured bu the RNAV function to take the aircraft down. The C208 situation is curious, I didn’t think AP had control of throttle. You’re unable to maintain airspeed by adding power?
Are you on autopilot the entire time from transition onward or handflying the approach?
The only aircraft with auto-throttle are the Longitude and possibly some of the stock airliners, so it’s up to the PIC to adjust power as needed to remain on GS, the AP will input pitch.
You must be in APR BEFORE the FAF. Not at, not after. Activate APR after the FACF so you are completely in correct switchology so all you’re waiting for is GS/GP capture.
CC, thanks. AP through the FAF, cutting throttle to a reasonable approach speed, fully configured for landing. I’ve tried descending a little below the published altitude to see if I could intercept the GS below the published altitude, but no joy with that method either. I’m going to try the approach into Manchester (KMHT) with the G36 as shown in the Kipontheground YouTube video suggested by meh1951.
So, just tried the RNAV GPS approach into Manchester on RW 06 and the system worked flawlessly, took the aircraft down to 500 feet and handflew to the ground. Now I wonder if it is situational, you have to be at the right airport for it to work. LOL!
You are correct. The C208 doesn’t have AutoThrottle. I have trouble timing setting the flaps. The AP makes adjustments when flaps are deployed. The C208 engine doesn’t respond quickly to throttle changes like smaller aircraft. Getting the aircraft in a stabilized configuration is part of an approach where I need lots of practice coordinating everything.
I will have to give a try. I gave up on Rnav other than following the altitudes from the charts. I have not no troubles with ILS. Thanks!
I’ve successfully landed at a number of different airports with a number of different aircraft Not sure what my initial error was (procedural probably) but if I activate the procedure before takeoff, follow the approach procedure at the proper altitude, configure for landing and activate the APR at the Final Approach Fix (FAF), I’ve found that it works all the time (so far… LOL). It is also useful in finishing off the 500 landings of the World Traveler Achievement. Thanks to the comments from the community!
Many think RNAV and ILS approaches are the same and try to fly them the same. However, RNAV GPS approaches are only similar to ILS, LOC, and VOR approaches. The terminology is different. Similar terms like GS and GP or DA and DH can be confusing. ILS approaches are somewhat standard for all airports. Many RNAV GPS approaches are not “standard” and some are quite challenging. I often practice an RNAV GPS approach multiple times using different weather settings. My current challenge is to fly the KSBS RNAV (GPS)-E approach and not hit a mountain. Sometimes I am successful In clear weather but unsuccessful at weather minimums.
This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.