Performance collection not recording descent performance

[oltsukoo]

I'm trying to collect a performance profile for my Aerobask DA42, but all the descent performance values in the current performance tab keep reading zero and won't track the airspeed, vertical speed and fuel flow.

Other flight segments are tracked correctly, the aircraft progress tab is showing current fuel flow and other flight data, and the log indicates that the descent segment is active.

LNM 3.0.17, X-Plane 12.2.0-b6

LNM log file: abarthel-little_navmap.log

XP12 log file: Log.txt

[albar965]

Not at my flying computer now to test.
Maybe there is a problem with flight plans having no en-route waypoints. Try with one or more waypoints added.

[albar965]

Also reset things before flying:

Alex

[oltsukoo]

Alright, I did another flight with 2 enroute waypoints and it seemed to work.

However, I don't know if that's actually what fixed it. When I was planning the flight, I found that having one or no enroute waypoints caused the elevation profile window to show a straight horizontal line at cruise altitude, all the way from origin to destination, with no climb or descent segments.

But when I finished that flight, reset LNM and planned another direct flight between two airports, the profile correctly displayed the climb and descent segments.

Could this be related? Does the performance collection take the elevation profile into account, and can it fail if the profile is invalid? Unfortunately I wasn't paying attention to this so I don't remember if the same thing happened on earlier flights where the performance collection didn't record descent data.

[albar965]

I'll have a look at this. Either I fix this limitation or have to add a message if en-route waypoints are missing.

Could this be related? Does the performance collection take the elevation profile into account, and can it fail if the profile is invalid?

Yes. You need a valid profile. The error message at the bottom of the flight plan window shows what is wrong or missing.

[oltsukoo]

Yet another flight, and the performance collection worked even with a direct flightplan with no enroute waypoints, even though the manual says that it wouldn't.

But upon further testing, it seems that having a flightplan that is too short will cause the elevation profile to fail to generate, and it'll just show a straight horizontal line at the planned cruise altitude.

So I think what may have happened on my earlier flights (which were fairly short) is that my initial performance data was incorrect enough that LNM thought I wouldn't be able to reach cruise altitude before starting the descent (even though this was not the case in the sim), and that caused an invalid elevation profile, which then caused the descent performance collection to fail.

The manual says that "a short hop will not suffice", but as far as I can tell, it doesn't explicitly and clearly say that the performance collection will break completely (rather than just produce inaccurate results) if there's no valid elevation profile with climb/cruise/descent segments. I think this is something that should be mentioned in a green "important" or yellow "warning" box in the manual.

[albar965]

Yet another flight, and the performance collection worked even with a direct flightplan with no enroute waypoints, even though the manual says that it wouldn't.

I just added this note yesterday. I'll add more.

A red error in the flight plan table and an invalid elevation profile will definitely cause issues. You have to see the climb and cruise phase. A straight line will also trigger a red error message in the flight plan table.

I cannot see the flight plan table in your screenshot. I'd keep this open to see any issues (press Alt+1 or see in menu Window).

[ricardo404]

This discussion is quite interesting, and I’d like to share some insights as well. I don’t have concrete proof yet to determine whether this issue is caused by X-Plane 12 in beta (the version I’m currently using is B6), but sometimes the aircraft performance data collection in X-Plane fails to gather information. For example, in the current performance menu, the climb and cruise data, vertical speed, and fuel flow appear as zeros. Restarting the data collection gets it working again, but you end up losing crucial data that should have been recorded during critical phases of the flight, such as climb and descent.

My connection to Little Navmap is established via LNM Connect.

My option to reset performance data collection every time I click "Reset Flight Plan" is enabled.

On a recent flight, I noticed that the system collected climb data normally up to cruise altitude, which seemed promising. However, when I landed, I realized that the descent data hadn’t been recorded—it was completely zeroed out. Something particularly curious also happened: Volanta didn’t provide me with FPM (feet per minute) information at landing. There was no data available, yet somehow it still recognized my altitude, as I was able to check the Volanta VSD graph. This makes me wonder if the issue stems from X-Plane in beta.

I was flying the FlightFactor 757 using performance settings based on successful previous data collections, with no error warnings related to the flight plan or profile.

I’m going to experiment with how I launch Volanta and LittleNavConnect! Normally, I open both simultaneously before launching X-Plane. This time, I’ll wait until the simulator is running before opening them, and I’ll launch each one in a random order to see if the final result changes.

[albar965]

Watch the actual fuel flow in the progress tab if this is zero when the collection stops detecting fuel flow. Some aircraft "doctor" values and can show no fuel flow. This rarely happens in X-Plane, though. I also fly X-Plane and haven't encountered this issue yet.

As soon as I have more time, I will carry out thorough tests.

[ricardo404]

Watch the actual fuel flow in the progress tab if this is zero when the collection stops detecting fuel flow. Some aircraft "doctor" values and can show no fuel flow. This rarely happens in X-Plane, though. I also fly X-Plane and haven't encountered this issue yet.

As soon as I have more time, I will carry out thorough tests.

Hi Alba, I have more information about this, looking here. I started a flight in LNM and reset the flight plan where, among other things, it reset the aircraft performance collection. I even went to the "current performance" tab and it was clean with only the inscriptions "Unknown Aircraft" and "no flight plan". As soon as I entered an airport in Xplane and opened LNM Connect, there was a change in the "Current Performance" tab to as if I had just completed the flight, see:

(Could this explain why, even after resetting the performance collection, you end up discovering that there was no collection, since there was an "empty collection" that interrupted what should have been a legitimate collection?!)

[albar965]

Hi Alba, I have more information about this, looking here. I started a flight in LNM and reset the flight plan where, among other things, it reset the aircraft performance collection. I even went to the "current performance" tab and it was clean with only the inscriptions "Unknown Aircraft" and "no flight plan". As soon as I entered an airport in Xplane and opened LNM Connect, there was a change in the "Current Performance" tab to as if I had just completed the flight, see:

(Could this explain why, even after resetting the performance collection, you end up discovering that there was no collection, since there was an "empty collection" that interrupted what should have been a legitimate collection?!)

Thanks for the screenshot, Ricardo. Loaded from last session, Finished might be the culprit. It seems that the collection falls back to this finished state when restarting LNM after a reset. A new reset should fix this.

I had no time yet to test this but this is already a helpful clue.

[albar965]

Test results so far:

1. Works with flight plan having no intermediate waypoints.
2. Works with broken flight plan (straight line in elevation profile).
3. Works without a flight plan, provided that the correct cruise altitude has been set in the Flight Plan window.
4. Reloading of status when restarting LNM does not work at all. Always reverts to finished, no matter if empty or not.

Let me know if you see other issues. It should be fine if you do not restart LNM.

[ricardo404]

Test results so far:

1. Works with flight plan having no intermediate waypoints.
2. Works with broken flight plan (straight line in elevation profile).
3. Works without a flight plan, provided that the correct cruise altitude has been set in the Flight Plan window.
4. Reloading of status when restarting LNM does not work at all. Always reverts to finished, no matter if empty or not.

Let me know if you see other issues. It should be fine if you do not restart LNM.

Thank you for this Alba.