Boeing 737 Max8 trim goes nuts when increasing the sim rate

Bug Reporting Hub Aircraft & Systems
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1

ISSUE DESCRIPTION

Description of the issue:
When increasing the sim rate more than 2x flying the Asobo Boeing 737 Max8 on the autopilot trim goes nuts constantly pitching heavily up and down and this behaviour continues even after returning to the 1xSimRate. The only solution to recovery is to decrease the Sim Rate to minimum, turn off the autopilot, turn off the autotrim, then turn back on autopilot and then autotrim and restore Sim Rate 1x, but this can result in either exceeding the G-forces or crashing the aircraft to the ground.

If applicable, which aircraft is experiencing this issue:
Asobo Boeing 737 Max8

[PC Only] Did you remove all your community mods/add-ons? If yes, are you still experiencing the issue?
No

FREQUENCY OF ISSUE

How often does this occur for you (Example: Just once, every time on sim load, intermittently)?
Exery time

REPRODUCTION STEPS

Please list clear steps you took in order to help our test team reproduce the same issue:

  1. Go any flight in Boeing 737 Max8
  2. Take off and turn the autopilot on
  3. Increase the Sim Rate at least 4x
  4. Observe the trim behaviour and aircraft itself

YOUR SETTINGS

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 User Support Hub.

What peripherals are you using, if relevant:
Thrustmaster Airbus Captain Pack

[PC Only] Are you using Developer Mode or have you made any changes to it?
No

[PC Only] What GPU (Graphics Card) do you use?
Asus GeForce 3070 Dual OC 8GB

[PC Only] What other relevant PC specs can you share?
Intel I7-9700K, MSI Z370, G.Skill 64GB DDR4 3600, Windows 11 Pro on 1TB Gamming NVMe, FS24 on 8TB WDC 7200 RPM 256MB cache, Creative SoundBlaster X-Fi Titanium

MEDIA

[END OF FIRST USER REPORT]

: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 OPā€™s steps to reproduce it?
ā€¢

Provide extra information to complete the original description of the issue:
ā€¢

If relevant, provide additional screenshots/video:
ā€¢

2

Yes 2x is about all I can run sim rate at with the Max due to these pitch changes. I also think LNAV goes wobbly on 4x sim rate too. It also has the most oscillatory ILS approach with engines spooling up and down creating porpoising effect. Itā€™s a very buggy aircraft.

4

Same here.

5

Do you have the same issue if you follow the OPā€™s steps to reproduce it?
ā€¢ It happens to me even on 1x sim rate. The plane keeps heading up and down when on autopilot.

Provide extra information to complete the original description of the issue:
ā€¢ My computer is on low performance hardware with Nvidia 1070, and I have to set graphics to low-end.

If relevant, provide additional screenshots/video:
ā€¢

6

I tried something unique. I set autopilot speed to about 228 and set my flight level to 399, and I was able to get 4x sim rate for longer periods.

7

I hope this issue gets sorted as you canā€™t do long haul flights in a reasonable time without sim rate working proper with the 737 MAX.

2 Likes
8

I am experiencing a similar issue. Whenever I fly the 737-800 in MSFS 2024 free flight, if ā€œauto trimā€ is selected in the assistances menu, the aircraft will porpoise up and down as the trim wheel (in virtual cockpit) spins wildly, oscillating from positive to negative values. This happens regardless of whether autopilot is engaged. I donā€™t Know what sim rate is and havenā€™t messed with it. Any known solutions to this issue?

9

Yep, same here. Going to 4x causes it too. Had a similar issue in MSFS 20.

10

For me it happened today at 1x :slight_smile: I just changed the view from external back to cockpit and my trim went fully UP and AP disconnected. Looks like trim settings are always dependent on PC resources somehow and not only when we go 4x or ather x

11

Just for awareness there was an Asobo 737 Max update with SU4beta 1.6.21 on Friday. I only noticed it because I have the 737 stored locally so had to update it. NO word on what changed though, no change log and nothing in the beta release notes as far as I can see.

1 Like
12

Still happening now on MSFS 24 on Xbox Series S

13

The AP moves the trim as itā€™s mechanism for changing the pitch (this is true IRL for modern planes too, older ones moved the yoke), rather than it being the automatic trim ā€˜helperā€™ function.

As I understand the sim-rate itā€™s not compressing action into a smaller amount of time (i.e time running faster), itā€™s objects move x times as far, in the same time.

The ramification of this is say at 4x rate, every time the AP observes the aircraft state it has moved 4x further than it would have, so this stimulates the AP to make much more dramatic changes.

Almost all aircraft porpoise a bit in sim (particularly at high sim rates) but autothrottle, particularly on jets like the 737Max, seems to exacerbate this as it cycles the throttle reacting to the speed change (which in turn comes from the pitch change). PC24 and Longitude bizjets porpoise dramatically at high sim-rate.

Iā€™ve had some success by using manual throttle in all of these situations, it doesnā€™t remove but does reduce the impact significantly.

1 Like