Autothrottle issues/questions

[Red4282]

Hello all, new member here. I primarily fly the  Inibuilds a320 v2 on Xbox, and have enjoyed it quite a bit. As a new simmer, I obviously had some hiccups here and there as I was learning more about the systems and procedures. However, I feel after hundreds of hours, I'm fairly familiar and comfortable flying. I am having one issue occasionally that Im not sure if its something I'm doing, or if there is something wrong with the aircraft/programming.

On difficult approaches with terrain, (examples: NZQN, Paro, etc), I have had several instances where the auto thottle just stops working. The most recent event, I can describe very detailed what happened, as I was watching it very carefully. I was coming into NZQN runway 23. I had my flightplan loaded from simbrief. However, for whatever reason, none of the SIDS and transitions will load properly. I select them on the MCDU and insert, but none of the waypoints show up. I tried them all. None work.

So as I was about to begin the descent, manually inserted all my waypoints from Simbrief into the MCDU. This seemed to work, as it accepted them and had what looked to be a good approach path. I took the Descent nice and easy, just to make sure terrain was not to be an issue, so i slowed my plane down early. At about 6500 feet or so, right before my last waypoint and final turn into the runway heading, I was at 180 knots (or flaps 1 speed). Approach mode activated. I could see one issue though, there was one last mountain top I needed to clear before I could descend any further, and on my current trajectory, It was going to be very close. So, I Disconnected the autopilot to flight manually, same way i would the last thousand feet or so into landing, and basically just level off to clear the mountain. As I did this, I noticed my speed starting to drop.  Engines were at Idle. I made it over the mountain, and started troubleshooting the lack of auto throttle. Still in clb detent, autothrottle still shows its active and engaged. Tried to do selected speed, and still no response. Selected flaps two, as I was getting close to stall speed. Speed keeps dropping. I tried the auto throttle disconnect button, the autothrottle button on the dash, moving the throttle to idle and back to clmb, and there is just nothing. Engines still Idle. Finally, the inevitable happens, and i hit stall speed, AFLOOR triggers and goes into TOGA. It is at this point when I can get the autothrottle back working. 

This only seems happens when I disconnect the autopilot early, to fly manually. Which is usually a difficult approach. My question is, like I mentioned before, I disconnect the Autopilot every single time I land at about 1000 ft AGL and the autothrottle never drops out. So why would this be any different? Is it because Im not at final landing speed? Is this some kind of bug? 

 

Also for clarity, Im using an Xbox controller. No yoke or throttles. Also not using the simple "y" button to turn off autopilot, I made my own key to disengage Autopilot, as that chime on landing was annoying. 

 

Thanks for any help!

[richboy2307]

Hi @Red4282

Thanks for your post. There are multiple issues questions raised in this post so I'll address them in bits below:

3 hours ago, Red4282 said:

I was coming into NZQN runway 23. I had my flightplan loaded from simbrief. However, for whatever reason, none of the SIDS and transitions will load properly. I select them on the MCDU and insert, but none of the waypoints show up. I tried them all. None work.

In the case of NZQN specifically, this is an issue with the simulator's Navdata API rather than the A320neo V2 itself. All Microsoft planes, including the A320neo V2, use the sim's internal data as a source for navdata, but sometimes part of that data is not relayed properly for aircraft on WASM API (Like the A320neo v2) , but would work on those using the JS API (WT 787/747 for example). NZQN is a well documented example of this and this is something for Asobo/MS to address in the long-run. 

An alternative solution is to use an entirely custom navigation database (navdata) such as one made by Navigraph (e.g. on planes like PMDG 737/ FENIX A320), however this is unlikely for "default" Microsoft aircraft such as the A320neo V2 that need to work with the sim's data, specifically on Xbox. For now though entering the waypoints manually, or visual flight is the only way around airports like NZQN.

4 hours ago, Red4282 said:

Tried to do selected speed, and still no response. Selected flaps two, as I was getting close to stall speed. Speed keeps dropping. I tried the auto throttle disconnect button, the autothrottle button on the dash, moving the throttle to idle and back to clmb, and there is just nothing. Engines still Idle. Finally, the inevitable happens, and i hit stall speed, AFLOOR triggers and goes into TOGA. It is at this point when I can get the auto throttle back working. 

I'm afraid I'll need a video clip preferably, or screenshots in order to truly assess what may be happening. As it could be misconfigured modes on the FCU or throttles not being in the proper detents also leading to misconfigured modes as a result.

How are you engaging selected speed? Are you pulling the speed knob in order to go out of MANAGED mode, and instead follow your commanded speed?

Once disconnected, the ATHR won't re-engage by simply moving the throttle into CLB detent, but rather you'd need to engage it from the FCU button and then ensure throttle is in the right detent.  

Also another thing to check is your 'Assistance Options', ensure they're all disabled to avoid any AI Pilot intervention that may be causing issues.

 

4 hours ago, Red4282 said:

This only seems happens when I disconnect the autopilot early, to fly manually. Which is usually a difficult approach. My question is, like I mentioned before, I disconnect the Autopilot every single time I land at about 1000 ft AGL and the autothrottle never drops out. So why would this be any different? Is it because Im not at final landing speed? Is this some kind of bug? 

There should be nothing that affects it in terms of whether you're landing at a "normal" airport, or at a mountainous one. Ofcourse, power settings will vary with density altitudes, typically the higher up you are above mean sea level, the faster your Ground Speed and the more power required, however the ATHR should be more than capable of adjusting for this in order to achieve commanded speeds, assuming that it is configured properly.

Thanks!

[Red4282]

4 hours ago, richboy2307 said:

Hi @Red4282

Thanks for your post. There are multiple issues questions raised in this post so I'll address them in bits below:

In the case of NZQN specifically, this is an issue with the simulator's Navdata API rather than the A320neo V2 itself. All Microsoft planes, including the A320neo V2, use the sim's internal data as a source for navdata, but sometimes part of that data is not relayed properly for aircraft on WASM API (Like the A320neo v2) , but would work on those using the JS API (WT 787/747 for example). NZQN is a well documented example of this and this is something for Asobo/MS to address in the long-run. 

An alternative solution is to use an entirely custom navigation database (navdata) such as one made by Navigraph (e.g. on planes like PMDG 737/ FENIX A320), however this is unlikely for "default" Microsoft aircraft such as the A320neo V2 that need to work with the sim's data, specifically on Xbox. For now though entering the waypoints manually, or visual flight is the only way around airports like NZQN.

I'm afraid I'll need a video clip preferably, or screenshots in order to truly assess what may be happening. As it could be misconfigured modes on the FCU or throttles not being in the proper detents also leading to misconfigured modes as a result.

How are you engaging selected speed? Are you pulling the speed knob in order to go out of MANAGED mode, and instead follow your commanded speed?

Once disconnected, the ATHR won't re-engage by simply moving the throttle into CLB detent, but rather you'd need to engage it from the FCU button and then ensure throttle is in the right detent.  

Also another thing to check is your 'Assistance Options', ensure they're all disabled to avoid any AI Pilot intervention that may be causing issues.

 

There should be nothing that affects it in terms of whether you're landing at a "normal" airport, or at a mountainous one. Ofcourse, power settings will vary with density altitudes, typically the higher up you are above mean sea level, the faster your Ground Speed and the more power required, however the ATHR should be more than capable of adjusting for this in order to achieve commanded speeds, assuming that it is configured properly.

Thanks!

Thanks for the reply. Good info to know as far as way points and such. All Ai pilot settings are disabled. As for selecting a speed, i use the "x" button to go into selected, and do this all the time. In this case, the blue triangle speed indicator, shows up but is totally ignored. I know the auto throttle shouldnt be affected by mountainous ones. However, "normal" approaches, I usually disconnect autopilot at 1000 ft, usually fully configured and on glideslope.  Where as mountainous, there is a good chance I may disconnect way early, even before Im fully configured for landing. Thought maybe there was a correlation. Next time it happens I will attempt to grab some screenshots.

[Red4282]

So just did a quick flight and tested some things. Took off from christchurch NZ headed for NZQN. Leveled off at FL320. Disconnected autopilot, pitched up and down and throttle adjusted accordingly. Began an early managed deacent, at 1k fpm, same thing, disconnected, and pitched up and down. Same result. Then began the more moderate descent where engines went to idle, and bam there it is. Disconnect and pitch up (or even just level off) and the engines just stay idle and speed plummets. Back to autopilot engaged and nothing. Manually dove down to get speed back up to magenta triangle then engaged autopilot and auto throttle came back to life. It seems as if you disconnect autopilot at any time the engines are in idle, the autothrottle becomes non responsive UNLESS you dive to get speed up to the magenta triangle and re-engage autopilot. At least thats what i think is happening.
 

Again, im not sure if this is actually how the plane is supposed to be or not. 

[Red4282]

I think I found my answer. This is correct logic as it appears something similar has happened in real life!

https://www.flightglobal.com/easyjet-incident-highlights-open-descent-mode-risk/121478.article

[richboy2307]

9 hours ago, Red4282 said:

It seems as if you disconnect autopilot at any time the engines are in idle, the autothrottle becomes non responsive UNLESS you dive to get speed up to the magenta triangle and re-engage autopilot. At least thats what i think is happening.
 

Again, im not sure if this is actually how the plane is supposed to be or not. 

I checked with the team.

TL;DR: This is expected behaviour if the thrust mode was THR IDLE at the time AP was disconnected. You'd want the thrust mode to be SPEED in order for the ATHR to continue to respond to pitch inputs. As such, it is recommended to disable both FDs when doing such kind of manual flying.

The team's detailed response is as follows:

Quote

This is actually expected and caused and easyJet to trigger A.FLOOR once. It's why the SOP when flying without using FD guidance is AP off + FDs off (to trigger the A/THR to SPEED mode specifically).

You can read more about the incident here: https://avherald.com/h?article=4835e8f2

Excerpt below is from the report (https://assets.publishing.service.gov.uk/media/578df05140f0b652dd00014c/Airbus_A320-214_G-EZTE_08-16.pdf ) :

"The AAIB discussed:

On the A320 series, when the autopilot is disconnected in OP DES mode, the FD remains engaged in thrust mode, commanding IDLE thrust, and provides pitch commands for the PF to maintain the target speed. Thrust will not increase when the pitch commands are not followed and there is a decay in speed, until the low speed protections activate. To revert to SPEED mode and resume variable thrust, the flight director must be switched off.

Flight crew are accustomed to the speed protections afforded by the A/THR system and the two events reported on by the BEA demonstrate that, if misunderstood, there can be an expectation that the A/THR will vary the thrust to maintain the target speed."

 

For illustrative purposes, note the two videos below, specifically how throttle responds in THR IDLE vs SPEED modes to pitch changes once AP is disconnected.

Scenario #1 - Thrust Mode: THR IDLE, Vertical Mode: OP DES

 

Scenario #2 - Thrust Mode: SPEED, Vertical Mode: VS

 

Thanks!

 

 

[richboy2307]

46 minutes ago, Red4282 said:

I think I found my answer. This is correct logic as it appears something similar has happened in real life!

Yes exactly, great detective work! 🙂

[Red4282]

Thanks for the detailed response and videos. Im assuming same is true for when in a managed descent and the throttle is in idle mode?

[richboy2307]

1 hour ago, Red4282 said:

managed descent and the throttle is in idle mode?

Yes, what matters more is the thrust mode - if its THR IDLE, it will remain so unless FD is off or VS used to engage SPEED mode.