Garmin has released system software 6.50 (since updated to 6.51, which is a mandatory update) for its GTN 750 and GTN 650 navigators. The new software adds several features, including:
- Vertical navigation (VNAV) capability when flying STARS and the initial stages of instrument approaches
- Along-track offsets in flight plan segments
- Destination airport remains in the flight plan when an approach is loaded (but the destination airport is removed when the approach is activated)
- A shortcut to the airport info page added to all procedure headers
- Load the approach NAV frequency from the approach header in the flight plan
- QWERTY keyboard option
The following sections highlight some of these features. For more details on how to use the functions, see the latest editions of the GTN guides, available in my Aviation Documents folder at OneDrive and from Garmin’s product pages.
The details about this update to the GTN series are in ASDN Service Bulletin 1860, the 6.51 mandatory udpate, and the GTN 725/750 SOFTWARE v6.50 PILOT’S GUIDE UPGRADE SUPPLEMENT.
Garmin also released system software updates for the G500/600 PFD/MFD and associated hardware. For details on those updates, see ASDN Service Bulletin 1861.
Garmin has also updated its free Windows-based trainer for the GTN series.
Note that these system updates must be performed by an authorized Garmin dealer or avionics shop unless you are flying a experimental-homebuilt aircraft.
VNAV Capability
The new software adds several vertical navigation features, best illustrated with examples.
Garmin has published a video that describes the VNAV feature in detail, here.
Suppose you are flying the RNAV RWY 08 approach at Lewiston, ID (KLWS), joining the procedure at the BIDDY initial approach fix northwest of the airport. The NoPT feeder route from BIDDY specifies an an altitude of at or above 5000 ft to EVOYU, followed by a descent to at or above 4000 ft to MABIZ, and then at or above 3400 ft to the FAF at GIYES.
With the new GTN system software, those segment altitudes appear in the flight plan page for the procedure.
The VNAV feature appears as a magenta vertical guidance cue next to the altitude tape on a PFD such as the new Garmin G500Txi (shown here) or the G500. Note that at this point in the approach, the LPV glidepath is a dim white diamond behind the magenta VNAV cue because the FAF is not the active waypoint and LPV is not yet annunciated on the HSI.
The VNAV cue provides advisory guidance to help you smoothly descend to each charted altitude as you fly the initial stages of the approach.
The LPV glidepath marker that displays approved vertical guidance replaces the VNAV cue when the FAF is active and the GTN system confirms that LPV minimums are available, as shown below.
Similar VNAV information and cues are available when flying a STAR, such as the MADEE FOUR arrival at Bellingham, WA (KBLI).
Note that the altitudes shown in the GTN flight plan list for this STAR are for turbojet aircraft. But you can easily edit the altitude if ATC assigns a more appropriate altitude when you’re flying a typical piston-powered light aircraft.
If you are flying an approach based on an ILS, LOC, or VOR, you can quickly retrieve the navaid frequency by touching the approach title, as shown below for the ILS RWY 16 at KBLI.
Along-Track Offsets
Suppose you are flying northeast along V2 at 13,000 ft. between ELN and MWH when Seattle Center clears you to cross 20 nm west of MWH at 9000 ft.
With the new software, you can easily enter an along-track offset and display advisory vertical guidance to help you meet the restriction.
Touch MWH in the flight plan, and then touch the new Along Track button.
To create a waypoint for VNAV guidance, fill in the information that corresponds to your new clearance.
Airport Information
An earlier version of the GTN system software included behavior that frustrated many pilots. When you loaded an approach into a flight plan, the destination airport was removed. If you hadn’t noted details such as the tower frequency, extracting that information from the GTN’s database was cumbersome.
In version 6.50, Garmin has added an APT Info button next to the approach title in the flight plan list.
Touching that button shows the familiar information window that provides touch access to details about the airport, including frequencies, weather, and other data.
QWERTY Keyboard
You can also choose a QWERTY keyboard instead of the alphabetical layout in previous versions of the GTN software. The option is available on the System Setup page.
BruceAir, LLC 
Found this via your link on Beechtalk.
Nice overview of the new software enhancements. Thanks!!
Bruce, thanks for the explanation of the new GTN 750 features. Much appreciate your time doing this for us.
Just had a system update (dual GTN 750s with G600 PFD and MFD) during annual and went flying without any warning or explanation of new features. Time to each waypoint is now gone from the flight plan screen, and there seems to be no way to get it back. Apparently, room had to be made for the new ALT column. Most significant, if an approach was loaded earlier in a flight, there seems to be no way to activate it. (There is “Activate Vectors to Final”, but as is well known, that’s not always a great idea.) A little bit more salient notification of serious changes would be a good idea. (I know they are buried in the new manuals, but believing that pilots are reading these cover to cover is the human factors equivalent of believing in the Tooth Fairy.) A simple pilot’s update calling attention to new features would be appropriate, I think.
Many thanks to Bruce for going through these changes!
Garmin does publish a supplement to the Pilot Guide that includes only the changes that apply to the new system software. You can find that document, and the complete guides and other supporting documentation for the new system software, in one of my OneDrive folders: https://1drv.ms/f/s!AneE1ZO1pQoRgtp-AG9vsnSROy-XSw
Very helpful, Bruce. For me, the lesson learned is that if maintenance folks are handling system updates, I need to keep after them to let me know that there have been substantial changes. Thanks for having the Garmin update document you mentioned on your site. I note that the Update Supplement is more than 90 pages without obvious page numbers. Really have to wonder how many pilots truly stay on top of this. These things really need to trigger major training events. If you are keeping up and teaching these things, Bruce, I’m sure you’ll have a lot of business.
Nice advice about activating the approach. That is how we solved it in flight; the surprise was that the system behavior was different from before.
One specific question: For editing the data fields in the flight plan page to show ETE or ETA for each waypoint, how do you do that? Our attempt was to press menu on the flight plan page. Then there is a key for “Edit Data Fields”, but it was grayed out and would not respond. I see in the Update document that they say:
1. While viewing the Flight Plan page, touch the Menu key, and then the Edit Data Fields key.
However, this function is definitely locked out on my system. Any ideas what to do about that? I’ve asked the Avionics folks to look into it.
Thanks again for very useful comments.
Whenever system software is updated in avionics like the GTN series, you should receive: 1) a new AFM Supplement (that document tracks changes made per the STC under which the GTN was installed and updated); 2) new user guides (at least PDFs); 3) logbook entries indicating the scope of the work. I can edit the data fields via the process described in the manuals. The supplement that describes the new/changed features is essentially the pages in the pilot guide that change. Each of the new areas is tied to a section number in the pilot guide.
You can always go back into a procedure and “reactivate” it by proceeding direct to a fix or activating a leg between two fixes that appear below the procedure title. That behavior hasn’t changed. Procedures are in one sense just additional fixes in your flight plan. I have several blog posts on this topic.
See for example: https://bruceair.wordpress.com/2014/12/03/flying-instrument-approaches-without-activating-the-approach/
As my blog post also notes, Garmin has updated its free Windows-based trainer for the GTN series. That simulation (a link to that tool is also in my blog post) is an excellent way to become familiar with new and changed features. For example, you can still edit the data fields in the flight plan page to show ETE or ETA for each waypoint if you prefer to see that information. As for activating an approach or other procedure that is in your flight plan, you can always scroll up to the fix where you want to begin a procedure (perhaps for the second time after flying a missed approach) and proceed direct to that fix or activate the leg that precedes it.
Nice summary, Bruce.
Hello Bruce,
I had the latest software 6.51 update done on my GTN750. I get an error message VNAV -Unavailable, Barometric altitude lost. I do not have a G5, so would that mean I do not have a barometric altitude sensor?
See section 4.3.3.1 VNAV Requirements in the updated GTN 750 Pilot Guide and the AFM supplement that you should have received from the installer. A baro-corrected altitude source is required for VNAV.
• Enablement by the installer
• A baro-corrected altitude source
…
For installation details related to en route vertical navigation, consult the
AFMS.
Hi Bruce, my name is Mike Stevens and I just had my GTN750 updated with 6.5,and 6.6. I went and flew today expecting to see Altitude as the first data field on my flight plan, but nothing had changed, nor did I get any 500 ft call outs on my practice approaches, which I thought was one of the key features. Per what I read in the supplement the altitude data field should have replaced the first field for VNAV. When I went to the utilities page my VNAV was the same as before installing 6.50. Was there not something set correctly at installation. I do not have a barometric altitude sensor, but still thought these features would work. I plan to call my installer on Monday. Thanks for any help. Mike
Section 4.3.3.1 VNAV Requirements in the updated GTN 750 Pilot’s Guide notes the prerequisites for the new feature:
• Enablement by the installer
• A baro-corrected altitude source
If en route vertical navigation is not enabled, the GTN provides a single waypoint vertical calculator. For more information, refer to section 15.1.
For installation details related to en route vertical navigation, consult the AFMS.
Hi,
I have GTN 650 and 2 GDU 370.
Trying to use VNAV, the GTN calculate TOD, BOD and VS required.
VNAV get armed in the GDU 370 but when reaching the TOD, the autopilote just continues at the same altitude an VNAV never get activated.
And, yes, the alt selected is lower than the alt at BOD in the profile.
The VNAV-profile looks good too.
What can be possibly wrong?
You don’t say which AP you have. The VNAV feature works only with the Garmin GFC 500/600. It also appears that your GTN 650 is configured for the VCALC function, not VNAV. You should talk to your avionics shop and confirm the correct settings.