I’m doing a flight from OMDB to GOBD onboard B777… The video below shows the HUD during the flight and as you can see the aircraft is popping up and down… How can i fix this issue now? I’m doing a step climb starting with FL340…
This is a known issue. The easiest way to solve this is to deselect the altitude select and just set the VS to 0.
I climbed in a very slow rate before reaching the required altitude up to 200 feet/minute… The V/S now is already set to zero
One thing I noticed… your speed, it’s a bit too low. Bump it up to M 0.84 which is the typical and optimal cruise speed for the 777.
You plane will probably still bop up and down despite that, but not as much. Also as earlier mentioned don’t have your ALT set via the A/P
I did… Still doing the same
In my experience climbing slowly doesnt help as the issue will just make itself worse. Just deselect the Altitude select. Turn off that off. Just fly with VS set to 0 to maintain your altitude.
Do i need to do that during all phases of the flight or this just because I’m heavy right now and things will get better once I burnt more fuel?!
Throught the flight although you might want to test with that and see if it continues.
For me personally, I have never encounter this issue at this rate, I do occasionally, have the plane go up and down about +100 and -100 VS, but ti fixes itself as I burn more fuel.
The issues from what I have seen is slightly different for each and every user. I have not had the plane go up and down +/- 500 fpm as in your video, so I would suggest to keep burning fuel and report back and see what happens.
I noticed that only would happen if your load is more than the MLW at first… I have flown B777 many times but didn’t get such issue always
Will wait until the aircraft becomes lighter and will then select the altitude mode (on)…
Additionally, if you would like to, try descending down to FL320, and see if that helps. by minimizing the bouncing a little :)
What is your current Airplane load?
I might have already found the issue. But I roughly need to know what your airplane load is
According to the video; it was loaded with 49% load…
I meant the aircraft’s load not the fuel load.
I’m just put this here, as something Seb mentioned earlier about excessive VS inputs that get countered back when reaching assigned ALT, too quickly.
The question is: What was your VS when you reached FL340?
I know about this… before reaching FL340, the climb rate was 200ft/min
Okay. I’ve flown the B77W for over 1500hrs, doing mostly SIN-HND/ HND-SIN route with 260 tonnes of takeoff weight and I’ve never had this problem. I suspect it’s because of the ridiculously high trim. Try setting it to less than 10% and see what happens. Don’t set it to 10% immediately, slowly let the aircraft do its work
Trim as far as I’m concerned has no effect on the aircraft pitch when the AP is active, so during cruise or any other stage of the flight, no matter how much Trim you have, if the AP is on, then the Trim setting is nullified until you regain manual control.