Inibuilds A320neo V2 Auto-Thrust malfunction in approach mode

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Are you using Developer Mode or made changes in it?

No

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Yes

Which aircraft are you reporting an issue about? (Please also add the proper tag for it)

iniBuild Airbus A320Neo V2

Which aircraft version are you experiencing this issue on? (You can find this listed in the Content Manager under the Aircraft Name)

iniBuild Airbus A320Neo V2

Brief description of the issue:

During approach, in approach mode, vApp not maintained, causing stall and auto thrust to jump to TOGA (regardless of throttle position). Ignores manually set target airspeed (or speed for go around); can’t disengage Auto Thrust (IP button unresponsive).

Provide Screenshot(s)/video(s) of the issue encountered:

Detailed steps to reproduce the issue encountered:

Begin final approach, config full, be in approach mode (on final), disengage AP1. Attempt to maintain constant angle approach at vApp speed. Speed will drop below stall due to lack of AT response, AT then freaks out and jumps to TOGA, AT switch locked out, speed will continue to increase past any set speed (vApp, go around, manual, etc.).

PC specs and/or peripheral set up if relevant:

Windows 11,

Build Version # when you first started experiencing this issue:

SU 15

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Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

2

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

I experienced the same issue on an Xbox console. I tried disconnecting the a/p and auto throttle multiple times but TOGO kept engaging as I lower the altitude.

3

Do you have the same issue if you follow the OP’s steps to reproduce it?

No

Provide extra information to complete the original description of the issue:

NA

If relevant, provide additional screenshots/video:

NA

4

Do you have the same issue if you follow the OP’s steps to reproduce it?

No

Provide extra information to complete the original description of the issue:

Providing the INIT B page weight data is completed after applying the EFB Payload the correct VAPP is calculated. If these steps aren’t completed properly VAPP will be too low which will probably trigger Alpha Floor protection on approach.

If relevant, provide additional screenshots/video:

1 Like
5

Moved to Aircraft & Systems for community assistance.

6

Do you have the same issue if you follow the OP’s steps to reproduce it?

yes

Provide extra information to complete the original description of the issue:

no only approach also descent mode. When descending, autopilot is only IDLE.

If relevant, provide additional screenshots/video:

7

Have you got the right weights entered in the MCDU? The FMGC calculates speeds based on the MCDU data only so if you’ve loaded extra pax/cargo/fuel the FMGC won’t know about it so could be calculating speeds that are too low for the actual a/c weight.

Thrust is often at idle during the descent. That’s normal.

8

I just did some test and even forcing the weights there was no issue with the AT maintaining the selected speed (Vapp), next time I will try with managed mode but this was just a quick test and I didn’t have a full flight plan.

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Also I forced the plane to enter A. FLOOR and TOGA LK to demonstrate that you need to follow the correct steps to disengage the TOGA LK, is not just moving the throttles up and down as that will not have any effect, neither just pressing the AT button (probably what you tried).

These are the steps to follow:

  1. Disconnect the autothrust on the flight control unit (FCU).

  2. Set the new position for the thrust levers (or return to CLB detent).

  3. Reactivate autothrust.

All this is from the FBW manual but it’s basically the same for the A320 V2.

And here is the demonstration:

If you still have issues I recommend sharing pictures and a video to see what could be wrong.

9

Just wondering what weight you were actually at and what VAPP that weight would’ve really needed?

As an example using the Simbrief calculator:

Landing weight assumed 48500kg VAPP 122 kts (equivalent of MCDU not being set up correctly)

But if the a/c actual landing weight was 58500kg required VAPP 133 kts

Would the 11 kts difference be enough to trigger Alpha Floor?

10

No it wasnt. I actually forced the A FLOOR by pitching up aggressively.

11

I experience the same problem as well. :confused:
Currently the autothrust on the IniBuilds A320v2 quite useless.
It frequently just ignores the airspeed that I’ve dialled in on the FCU – and the autothrust light is on and throttles are in the correct CLB detent.
eg. I’ve commanded 180kt (to slow down from say from 250kt), and instead of spooling-down to flight idle, the engines just do the opposite and spool-up to near max thrust ! (And no, I’m not in alpha-floor / TOGA lock !)

12

It will be nice to post screenshots/videos. Otherwise its difficult to see whats happening.

13

I’ve never had this issue, are you sure the throttle is in the right location? e.g. climb and not MCT? Also when you set 180 try pushing the middle mouse button of the speed dial to ensure its activated.

14

Yes, throttle is correct position. In CLB. Not MCT.
Some other observations while taking off manually, and comparing like-for-like with the FBW A32NX.

Some notable differences:
Set a speed in the PFD – say 170kt.
Then take off in manual TOGA.
Then once I am airborne…
Set thrust levers to CLB.
In the iniBuids aircraft the autothrust lights up without you pressing it.
In the FBW the A/THR button does not light up.
In both aircraft, after you lift off, the V/S panel on the FCU shows a number like +700.

Then on the IniBuilds, the engine thrust stays high and the airspeed increases to above what you had set on the FCU…Until I reach about 3,000ft, then all of a sudden it starts to obey the speed that you had previously set prior to take on the FCU.
However, on the FBW, you can press the A/THR button immediately once you are airborne and it will obey the speed that you had set on the FCU – even if you are say at 800ft altitude after take off.

Question: Can you please explain these differences?
And which aircraft is behaving correctly?

15

Hi DreadfulHydra50

So I thought I’d give this a try, I’m not sure I’m seeing what you are seeing, I recorded what I see, is this what you are experiencing. The Inibuilds and FBW seem to be doing very similar things. This is the inibuilds version I’m using here:

Zooze74

2 Likes
16

Let me be clearer on what I experienced, as I wrote the bug report rapidly in a fit of annoyance:

  1. All FMC values on all pages (init pages one and two + including correctly calculated block, zfw, cg, etc. winds and IRS init, all perf pages including approach with correct weather, vapp, radio altimeter and so on).

  2. Was on approach to KBGR ILS Zulu for runway 15, flying the approach manually with AT, just passed UMAIN (FAF for 15) at 2100 feet. vapp was set for 140.

  3. On final, with AT engaged, it was not maintaining any set airspeed, the speed decayed below 130 until stall warning with no response from the AT (e.g no spool up). Throttle position is set to climb (as it is during all phases past takeoff, prior to retard callout).

  4. Finally, without any commanded input, it then went to TOGA (alpha floor), though I don’t recall seeing TOGA LK indicated on the PFD, though I was distracted, so I might have missed it.

  5. I then manually set the speed to 165 preparing to execute a missed approach (since approach was no longer stabilized, to say the least). As speed was now above stall and was rapidly increasing, there was no danger of such. I attempted to disengage AT by hitting the AT button on the FCU, to cycle out of TOGA LK. This was the point where things became unrecoverable.

  6. AT continued in TOGA regardless of AT button presses or throttle position detent, far past any safe airspeed for the configuration. AT switch was not responsive (as in it remained lit green regardless of presses or throttle position).

  7. No throttle related commanded input was respected, there was no way to retard thrust, regardless of other aspects of configuration, trim, flight mode, pitch, etc. Ultimately, I had to abandon the flight as the aircraft was effectively uncontrollable (I could have killed both engines, and attempted an unpowered landing, but I wasn’t in the mood).

There are two big issues: first, AT should have maintained airspeed and didn’t, allowing the plane to fall into A FLOOR territory (actually past, as I got a stall warning) before responding; second, once in TOGA LK (?), it wouldn’t exit no matter what I did or what the disposition of the aircraft.

17

I just saw this post on the IniBuilds Discord page:

A320V2 slows to A.Floor on approach

29 May 2024NEW

CrossHyparuOP — 29/05/2024 04:28

I just did a flight with the A320 and during the approach with the A/T set, the plane slowed to A.Floor, far below VAPP. VAPP was about 136 and the plane slowed to around 125, then A/Floor activated and immediately tried to initiate a go around. This happened twice. I had to disable the A/T and the AP to get it to work properly.

18

And this…

A320neo climbs instead of OP descent when on manual path ahead and flight director pitches up

A320neo

1 June 2024

kritikvOP — Yesterday at 18:05

I was approaching KSMF17L, there was manual path ahead after end of the STAR, I instructed open descent from 4000 feet to 2000 feet for an ILS approach. The FMA shows OP DES 2000 in blue however the aircraft pitched up and started climbing infinity and stalled in managed speed. I pulled V/S mode however V/S was not showing and FMA kept showing OP DES and climbing infinity. I recovered the aircraft from stall however it should have descended at first without any problem.

19

But it does IRL: A320Neo - Cockpit Takeoff

As you can see once the throttle levers are in FLX/MCT the A/THR illuminates in the FCU and it appears blue/cyan (armed) in the PFD FMA at the top right, when the levers are moved to CL the A/THR message in FMA becomes white.

1 Like
20

Thanks for the video. I can duplicate all of this no problem – in both the IniBuilds and the FlyByWire.
However, there is one crucial difference after the manual TOGA takeoff :

~ In the FBW, Scenario:
At 500ft I decide to level off by pushing the sidestick forward (say to avoid a stray aircraft in front and above me). I set the thrust levers into CLB detent and pull the Speed knob to the pre-set 170kt. The FBW’s engines immediately spool down and the airspeed settles at 170kt.

~ In the IniBuilds, if I do all the above, the engines just keep blasting at takeoff thrust, while the airspeed trends to an overspeed situation.

I can’t believe the latter scenario is meant to happen.
Q: Is my intuition misplaced? And is there an intended reason for the aircraft to keep on accelerating ad-infinium at 500ft even though I have set 170kt A/THR and the thrust levers are at the CLB detent?