747 autopilot Altitude won't hold at certain weight

I’ve noticed that past a certain point of weight on the plane, no matter what altitude is set on the autopilot, when the altitude hold goes from V/S to ALT the plane will go over and under it (like it’s over correcting the trim) and will get increasingly worse. I’ve known that I could fix this by making the plane hold at 0 vs instead of putting it in alt mode but sometimes winds and other atmosphere things will slightly knock the plane around and won’t go back to the altitude. It is also annoying to get the plane to hold at 0 vs all the time. This shouldn’t be a problem on short haul flights, but since this is a 747 it can go long range and I’ve been planning a flight from KLAX-OMDB which uses around max fuel which ,means heavy weight on the plane but think it would get annoying at some early point. Is this going to get fixed in this month’s update? Also I don’t own the premium version so I don’t know if the 787 does this too.

I’ve managed to get out of a particular nasty one with the 747 on autopilot and in cruise. It was fluctuating by 600 feet. 300 up and 300 down, just non stop. I managed to stop it by lowering the speed. Then when it settled down, I slowly increased the speed and it stayed on altitude. Perhaps still dipping and rising a bit but no more than 50 feet or so.

interesting, I think that can work, what speed and altitude did you use?

Oh good question… I think I was at 39.000 feet and I lowered from mach .85 to mach .81… but this is from a tired memory. Something like that. Two or three clicks down. Until it stopped. Then back up again per click. I don’t know if it would have gone crazy again if I had flown longer. It was a short flight.

This issue is similar to the Airbus ‘rocking’. With the Airbus it’s turning left, turning right, turning left… Different problem but also autopilot not being able to do its job properly. That rocking of the Airbus is really nauseating :nauseated_face:

Update: So I’ve tried multiple weights, and balances, and I can safely say that the planes alt and vnav mode can’t hold the altitude for ■■■■, also lnav swings left to right like the a320neo but a bit slower, I assume that all of this will be fixed in patch 2 since “Airliner system updates” and “Airliner avionics updates” are in the patch note highlights, if it doesn’t, then oh well it is what it is.

Already logged a ticket for this on Zendesk. Got the automated response that they’ve added it to the internal tracker.

is that a good thing?

Not sure if it’s good or bad, all of my tickets have had the same response.

Another update: The patch update didn’t fix it, ill probably reinstall the game and see if it’s just a corrupt file or something, if not well, once again, it is what it is.

I put in a ticket for this when the game came out. Got an automated response as well. I was hoping this would be fixed in most recent patch, but no dice.

Hope this gets fixed soon. I love the 747 and am upset that it’s basically unusable,

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yea there are waaayy too many issues with the 748, honestly it’s just annoying, fuel, autopilot, functionality, nd map using a 2d map which makes the map on it look curved towards the poles, physics (cruising especially), etc… I just can’t with this simulator’s airliners in general, and it doesn’t look like they are getting fixed anytime soon, i’m out.

Man I hope they fix this

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Today I tried my first flight with 747 and had same issue above.
Plane goes up and down like a maniac.

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Same issue here. Let’s vote this up guys :slight_smile:

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Ii think this has been mentioned before but the autopilot logic is all over the place. I just can’t get the aircraft to fly properly with the autopilot, to the point it puts itself into a bank and spins into the ground. With CMD on some functions work, then they stop working and I can’t turn CMD off. FLCH locks itself on and then HDG doesn’t function properly.

I think there are major issues with the autopilot in general. I see strange behaviour on other aircraft as well.

By the way, I’ve tried it with joystick plugged in and not plugged in. So, that’s not the issue.

The PID algorithm isn’t great for this aircraft either. A FLCH, when it works, overshoots a climb by 500 feet. The vertical speed then tends to fluctuate between climbing and descending when it tries to get back to the selected altitude.

Asobo probably needs to revisit the entire autopilot system rather urgently.

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Oh boy, the 747 just get worse and worse.

When using autopilot to ascend to instructed height, the 747 wildly pitches up and down during the ascent. Will ascend for 2000ft, then abruptly descend 1500ft.

This happens in both VNAV & FL CH mode. Seems ok when using V/S mode.

Also… when final altitude is reached, 747 will pitch up and down by +/- 300ft. Essentially un-flyable.

Dear all,

The problem starts in the the airplane is not following flight plan the complete route in the last points is It requires turning right and the plane is going straight ahead, loosing the route and the flight

Having the same issue with the current version, 747 keeps oscillating at cruise alt +/- 1000 ft

This plane is litterally unflayable. It would take me a few hours to list all the bugs I have found, all of them reported by alpha testers as far as I know.

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I have about 2000h on the PMDG 747 and another 1000h on the PMDG 777 and I am not able to controll the FS2020 747. I tried to fly a short trip from Munich to Zurich today on low alt (13.000ft) and after the autopilot nearly crashed the plane two times I flew the route manually and it was just not possible to controll the Boing. I´m really disappointed about this aircraft. The scenery is really incredible but the performance of the airliners and the AP behaviour ist terribly.

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