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FWAviation

Autothrust issues during approach

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I am using version 1.2.3.2 and in that version, I currently always run into autothrust problems when doing an ILS approach. I just tested it with the Lufthansa A320 D-AIZQ from the default livery set, during an approach to EVRA's runway 18 (default scenery) with default weather (scenario "Fair Weather", i.e. with only very light and steady wind during approach). But I did many other ILS approaches at various airports in the last few weeks and always had the following problem in the Airbus:

 

Until I intercept the glide slope, everything is fine and autothrust is running as it should (keeping an airspeed of 180 knots). But as soon as the autopilot catches the localizer and glide slope and autothrust reduces to idle (also because of me reducing the managed speed to the landing speed of 138 knots), the speed mode display on the PFD flickers between "Speed" and "CLB". At first, the speed falls slightly below the 138 knots bug, then it oscillates more heavily leading to the "Speed! Speed!" voice sounding during almost the entire final approach. Autothrust almost never reaches the actual set airspeed of 138 knots, right until touchdown.

 

I left the autopilot and autothrust on until touchdown for this test flight. And as I said, there was no gusty wind during final approach which could lead to those speed oscillations. And I also always watch out that the landing speed is in the "green zone" (so to speak), i.e. well above the stall zone on the PFD's speed display. Even when I increase the set airspeed to 143 knots, I get big oscillations in the airspeed and the flickering "Speed"/"CLB" display. Only the "Speed! Speed!" voice is silent then. It's funny that this problem only occurs as soon as I have caught the glide slope, and not before that. Even during climb with a set managed speed of 170 knots, I get no oscillations. So it is probably not a problem related to low airspeeds.

 

I have checked whether I have hit the "Climb" detent on the A320 throttle correctly - I have. I also have not changed the settings for my Thrustmaster throttle recently. I use FSUIPC, though. Could this create issues? Or is the issue possibly add-on-related? Does anyone else have those issues, too? I am flying in P3D v4.4, by the way and had no autothrust issues in earlier versions of the Airbus Professional.

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No, I don't have this behavior on my A319s.
But for more clarity, a few questions:
You filled out the APPR page in the FMC?
Autothrust was always on with "---" in the display?
You know that the speed is automatically reduced and adjusted to the flap position? There is no need for manual changes from the pilot's side.

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@Hoffie3000 No, I did not fill out the APPR page. In my test scenario and (I believe) most of my other flights recently I flew without a flight plan, mostly only a short pattern around the airport and then landed again.

 

Yes, autothrust was always on. Autothrust always tried to fight against those speed oscillations and the switch of speed modes (between "Speed" and "CLB"), but without much avail. The "Speed! Speed!" warning sounded anyway most of the time.

 

And regarding your third question: Yes, I know that. But since I flew without a flight plan or a programmed FMC, I had to reduce speed manually with the corresponding dial on the MCP. This always worked very well in the past, without any speed oscillations and speed warnings. So something has changed - either due to a bug in version 1.2.3.2 or due to any conflicting software on my part (FSUIPC etc.) or issues with my throttle.

I have not noticed similar problems with other aircraft yet, though.

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As far as I am aware it was a long time ago since any of that code was altered. Certainly not in 1.2.3.2.

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Some screenshots might also be helpfull here, it is always very hard to follow up on such a situation without seeing what actually happens.

Or even better a video if you can take one and upload it somehwere and post the link here.

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Vor 1 Stunde, Emanuel Hagen sagte:

Some screenshots might also be helpfull here, it is always very hard to follow up on such a situation without seeing what actually happens.

Or even better a video if you can take one and upload it somehwere and post the link here.

 

I will try. Can you recommend a good (and easy) screen capturing software (freeware, preferrably ;))? Otherwise, I would have to take a video with my mobile phone or such.

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If you use an nVidia card it might have one included already. Otherwise I don't really have any recommendation, sorry.

In the worst case you mobile would do the job as long as everything is readable.

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There are a few ways to do this in Windows 10.... already built it for you!  See HERE for more information on this.

 

I use (and love) ScreenShot Capture.  It's free, but you have to get a free serial number once a year for three years (it reminds you) and then it's completely free.  It's the best screen shot software I've ever used, but given it has a lot of features it takes a few minutes to learn and setup.

 

I hope this is helpful to you.

 

Best wishes.

 

 

 

 

 

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To @Emanuel Hagen and everyone else who is concerned: Here is the video.

 

https://www.youtube.com/watch?v=7uBnPgqe9P0

 

And thank you for your hints, Emi and Dave. Dave, I was actually looking for a video recording software. For screenshots, I can also recommend FireShot which is (I believe) an add-on available for Firefox. It's free and does a nice job as well. For the video, I used Nvidia Shadowplay.

 

Regarding the video: I hope that it is helpful. As you can see, it starts during the capturing of the EVRA Runway 18 localizer, shortly before intercepting the glide slope. You will notice that the speed/thrust oscillations start as soon as the plane captures the glide slope and the engines are being idled by autothrust. I also increased speed to 143 knots for a short while in order to show you that effect. And I pointed out that the throttle in the A320 was in the "Climb" detent all the time. Please ignore the Ryanair Boeing 737 on the runway shortly before my touchdown. It's obvious that I did not care about the proper landing direction in this test flight. ;)

 

On a side note, you will notice at 1:03 and 4:13 that the autopilot makes a sudden slight right turn and then back to the left during approach in order to stay at the localizer. This is pretty typical for my ILS/autopilot approaches in the Airbus Professional family. And I believe this has been reported here already by other users - and the probable cause you guys named in those cases were FPS drops due to the loading of scenery. I do not notice any unusual FPS drops or visual scenery loading effects at those two points, though. So if anyone has an explanation for that problem, too, that would be much appreciated as well.

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9 minutes ago, FWAviation said:

Dave, I was actually looking for a video recording software.

 

Ah, thanks for the update!

 

I've used several different programs for both Video Recording and Steaming, and I can't recommend OBS Studio any higher!  And... it's free, easy to install and setup, and allows to you record, stream, or do both!

 

Best wishes!

 

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Have you filled anything on INIT A and INIT B pages? At least on the right MCDU I can see initialize weights message. The Airbus is not intended to be flown without filling the items with orange boxes on INIT A and INIT B page. This can certainly lead into some unexpected issues.

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@Secondator No, I have not filled anything on the INIT pages. But until recently, that never created any problems in flight for me (at least if I only wanted to fly a short pattern, without any flight plan and such), especially not with autothrust.

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While you should have filled the FMC I agree with you though that at least in selected modes it should be working even without FMC information entered.

 

Not taking any gurantees here for the real aircraft, you never know with Airbus.

 

I believe what is causing your issue here is that the selected speed is jumping from your target down to 100kt for some split seconds every now and then. This causes the thrust to reduce and the to rise again, leading to an average N1 slightly below what would be needed to maintain your target speed.

While probably unrelated I want you to do a small test for me please: Could you try to set the speedbug to the top of the amber bar +15kt (instead of the +5kt as in your video) please and see if the speed gets stable anywhere before going into the amber bar? If yes, at which speed is this?

This might give us a hint if my above theory is correct.

Obviously we still have to find the cause of the target speed jumping down itself.

Do you have anything connected to your computer which might try to set the target speed? Maybe some hardware FCU, MCP, etc.?

Does the same happen in managed mode (then of course with a fully programmed FMC)?

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vor 5 Stunden , Emanuel Hagen sagte:

While probably unrelated I want you to do a small test for me please: Could you try to set the speedbug to the top of the amber bar +15kt (instead of the +5kt as in your video) please and see if the speed gets stable anywhere before going into the amber bar? If yes, at which speed is this?

 

Sorry for the stupid question, but what exactly do you mean with "top of the amber bar +15kt"? On the speed tape of the PFD, there is a magenta portion between approximately 136 and 120 knots (with flaps set to the "full" position), then there are yellow stripes between 120 and 110 knots, followed by the red stall portion of the speed tape which sits at 110 knots and below. So I see no amber bar there. If you meant the magenta portion, the speedbug already sits at the top of that (by choosing 138 knots on the MCP). Or did you mean that I should simply add 10 knots to that, i.e. choose 148 knots and then gradually go down from that in order to see when the oscillations start?

 

If yes: I can do that, but as you could see in my video at 1:06, the speed mode flickering starts already at 180 knots while the engines are spooled down to idle because of the glide slope interception. So I do not expect the speed getting stable at any speed below 180, at least not in landing/approach configuration.

 

In order to answer your other questions: No, I don't have any hardware FCU, MCP etc.. I only have a fairly simple Thrustmaster throttle (T.Flight Hotas X) consisting of a joystick and a throttle quadrant.

 

And yes, I will try a flight in managed mode with a fully programmed FMC and report the results.

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Addendum: My apologies, I misread the amber bar as a magenta bar (I couldn't recognise the colour properly in the video). But even then I don't quite understand what you meant by "to the top of the amber bar" because the top of that bar is 136 knots in landing configuration in the video above. But I reckon you meant 153 knots (138 knots + 15 knots), right?

 

I also just completed a short flight from Tallinn to Riga in the D-AIZQ A320 with a fully programmed FMC and had no speed oscillations on final approach (at a VAPP speed of 134 knots). But I noticed that the FMC calculated a totally wrong cruise speed. After departure in Tallinn, it set a correct climb speed of 250 knots until 10,000 feet, but after that, wanted to reduce the speed to 198 knots (even for cruise!). So I had to intervene manually and set a speed of 320 knots for my cruise in 24,000 feet. For landing, I then returned to managed speed, i.e. the aforementioned speed of 134 knots.

 

I had that "wrong cruise speed set by the FMC" problem already at an earlier flight with a fully programmed FMC one or two weeks ago. So it seems to me as if the speed management in total is a little bit botched currently in my Airbusses. I don't know why that could be. Besides the latest NavDataPro AIRAC cycle (1904) and a few airports, I did not install anything new or make any changes to my P3D during the course of the last few weeks. The update to version 1.2.3.2 is also already more than a month ago. @Secondator helped me with that after I ran into some problems after a wrongly configured virus protection on my system (all that is fixed now). So what can it be?

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I also did the second test you asked for, @Emanuel Hagen: I just completed a flight from and to EVRA (just a short pattern without programmed FMC) and chose an approach speed of 153 knots. As expected, I got speed and speed mode oscillations there as well and autothrust never managed to reach the 153 knots, falling below that speed (it was mostly at 148 knots or even less during final approach). Any ideas?

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How do you load the Airbus, do you use any default aircraft which may have the autopilot engaged at 100kt or less in the defautl scenario?

 

And do you use a betaversion or the latest stable release?

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@Emanuel Hagen My default scenario consists of the default Mooney Bravo sitting on runway 26R of Munich Airport, with its motor running at idle and its autopilot not engaged. I do not load that scenario first, but immediately after having started P3D, I choose the Aerosoft Airbus Professional from my list of aircraft and an airport, and then go flying.

 

I never had any problems with that procedure, and I have been using the Mooney Bravo default scenario for two months now. I got those autothrust problems in the Airbus only a few days ago. And the wrongly calculated cruise speeds in the FMC occurred for the first time about two or three weeks ago. So I don't think that there is a connection between my default scenario and the recent problems.

 

As mentioned above, I use version 1.2.3.2.

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@Emanuel Hagen Is there anything I can do, do you have all the information that you need? Could it be wiser to return to version 1.2.3.0, for example?

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On 4/11/2019 at 10:24 AM, FWAviation said:

I got those autothrust problems in the Airbus only a few days ago.

What did you change on your PC and or Sim at that time?

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vor 1 hour , mopperle sagte:

What did you change on your PC and or Sim at that time?

 

No changes on my PC at all recently (besides the occasional Windows update, but that was already after the autothrust problems occurred). The only changes in my sim in recent weeks was that I installed a couple of (P3Dv4-native or -compatible) sceneries and the latest NavDataPro AIRAC cycle 1904. I have touched no settings in my sim, so I see nothing so far which could affect autothrust behaviour in the Airbus. Or can a scenery or an AIRAC set alter any files in such a way that even such a feature inside an airplane add-on can be affected?

 

I use FSUIPC, though - and I know that there have been cases where this created bugs with the throttles or other hardware. Could this be a trace to follow?

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vor 19 Stunden , Mathijs Kok sagte:

Are you handling the throttles through FSUIPC?

 

 

If you mean by that, "have you configured your throttles through FSUIPC, i.e. have you changed sensitivity of thrust, rudder etc. through FSUIPC", then yes.

 

I'd just like to point out that I have been using FSUIPC since mid-January now, so way before my current autothrottle problems in the Airbus started. And I haven't changed any of my FSUIPC settings since January. But still, I wonder whether there's something in version 1.2.3.2 reacting more sensitively to FSUIPC than previous versions of the Airbus Professional that I operated. It might also be a change in FSUIPC that went unnoticed by me (although that is probably highly unlikely). Or the problem might still be not connected to FSUIPC at all.

But if you have any idea what I should change about FSUIPC (at least for a test), I'm of course open to that.

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Hi FWAviation,

 

I had the same issue with 1232 version (reinstalled 2 times, same behaviour). Each approach ended by a crash before reaching the runway. Finally ended this by going back to version 1230 that has no issue like this.

 

With the 1232 version I also have to mention that the speeds numbers displayed on the speed tape (top and bottom, blue numbers) of the PFD are blinking rapidly during the climb phase (never seen that on 1230, in selected speed mode)

 

Patrice.

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On 4/13/2019 at 9:44 AM, FWAviation said:

 

If you mean by that, "have you configured your throttles through FSUIPC, i.e. have you changed sensitivity of thrust, rudder etc. through FSUIPC", then yes.

 

I'd just like to point out that I have been using FSUIPC since mid-January now, so way before my current autothrottle problems in the Airbus started. And I haven't changed any of my FSUIPC settings since January. But still, I wonder whether there's something in version 1.2.3.2 reacting more sensitively to FSUIPC than previous versions of the Airbus Professional that I operated. It might also be a change in FSUIPC that went unnoticed by me (although that is probably highly unlikely). Or the problem might still be not connected to FSUIPC at all.

But if you have any idea what I should change about FSUIPC (at least for a test), I'm of course open to that.

 

We are not aware of anything changed in this regard. 

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