Autothrottle re-engages after leaving runway [747/787]

Bug Reporting Hub Aircraft & Systems
, , , , ,
1

:wave: Thank you for using the Bug section, using templates provided will greatly help the team reproducing the issue and ease the process of fixing it.

2 tags are required: One for platform, and one for aircraft.

Are you using Developer Mode or made changes in it?

No

Have you disabled/removed all your mods and addons? If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the Community Support section.

Yes

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

787, 747

Brief description of the issue:

After performing a manual landing by using the correct autopilot and auto-throttle disconnects (read: NOT the disconnect bar and NOT the AT/ARM switch) the engine levers will begin to move as soon as the PFD mode reverts from LOC to TO/GA. Essentially engaging a soft, un-commanded TO/GA press. I’ve checked my controls, there are no conflicts and this issue is non existent in other addons.
This problem will NOT manifest if you either do an autoland or use the incorrect method for disengaging the auto-throttle via the AT/ARM switch.

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

Detailed steps to reproduce the issue encountered:

Load up on an ILS approach and use the throttle disconnect button for the A/THR. Land manually. After vacating the runway and the modes on the PFD revert to TO/GA, if your AT/ARM switch is in the ARM position, the throttles will begin to increase power.

PC specs and/or peripheral set up if relevant:

irrelevant

Build Version # when you first started experiencing this issue:

SU13

:loudspeaker: For anyone who wants to contribute on this issue, Click on the button below to use this template:

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

787 manual is incorrect then?

Passing 1,500’ AGL the FMS will check for auto land conditions; you may execute an auto land on this approach. If all conditions are met for auto land, you will see the text LAND 3 indicated on the PFD below the FMA. This indicates that auto land conditions have been met and you will see in the PFD FMA that ROLLOUT and FLARE modes become armed.

You should be prepared to disconnect the auto throttle during flare, which you can do either with the A/T ARM switches on the Glareshield MCP, or with the side button on the throttles.

Once flare mode becomes active promptly disconnect the auto-throttle and bring the thrust to idle in preparation for engaging reverse thrust upon touchdown.

1 Like
3

Read the description again.

4

It’s my understanding that you are supposed to use the disconnect bar

How exactly are you disconnecting? Are you using a key bind?

5

No, you never use the disonnect bar during normal ops, at least not IRL.

2 Likes
6

@Ioanb92 The FDs are usually switched OFF when vacating the runway.
That said, I have no idea why the are switching to TOGA on their own.

1 Like
7

Does the problem happen IF you do use the disconnect bar?

8

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:

You must land with A/T on and leave A/T active when exiting on a high speed exit.

When the Rollout Guidance loses centreline off the scale, it initiates a go around mode. Possibly only if the spoilers are already retracted, autobrake disarmed, and flaps are retracted at least one increment from landing flaps - but I’m not sure any of those has any effect on it, just following same steps from other occurrences. It seems to be tied to the Rollout Guidance centreline scale.

This may be realistic, but I’m not sure.

I have read online information that both says to leave A/T on during landing (as with 787/777), and other places say to turn it off before short final as with 744. I believe the FCOM is not publicly available, so it’s hard to find info.

Perhaps us simmers experiencing this bug are missing a step disengaging A/T during rollout when bringing thrust levers to idle.

If relevant, provide additional screenshots/video:

Will provide some videos soon.

9

You didn’t miss anything, you’re among the few that actually know how how the autothrottle is disengaged during the approach. The reason this is so underreported is because everyone does it the wrong way by flipping the switch which completely disables the system, except the moment you vacate you will see TO/GA come up on the PFD, just that it can’t command engine power since the system is disabled.

Can’t say im surprised in the slightest that its still not fixed.

1 Like
10

Thanks, good to know I understood it correctly. I forgot to include this in my bug reports but I believe the thrust limit is also wrong sometimes on approach/landing. It stays in CLB when my understanding is it should be in GA.

Massive props to the WT guys, they’ve done an incredible job. But the mod they did for the CJ4 prior to being integrated into the Asobo/MS system was far superior to anything since.

The CJ4 itself has been rendered unflyable for me due to mouse input soft lock bugs when using freelook that weren’t present in the external mod, and there is no option to disable FMS keyboard input. Had to abort my world tour halfway through because of that. And the Salty 747 mod never had the janky autopilot/FD modelling that is now present either. 2 steps forward, 1 step back.

Still, it’s movement in the right direction, which is great to see. I just hope they follow through and fix the last 10%. When I pay 100% of the price for a product I do expect it to be 100% functional, not somewhere between 60-90%, which has been the MSFS experience thus far.

11

I don’t know if its realistic but thrust limit is set manually on the thrust limit page. I usually set it to GA just prior to passing the IAF.

12

Theres also another issue, while landing with the athr disabled properly, the engines will begin spooling in the last moments, leading to long landings. This should also be fixed asap..