Violent pitching/crashing after autopilot disconnect
Folks in the P3D Pro version of the aircraft I've had it three times now where, immediately after autopilot disconnect on the approach, the aircraft violently pitches nose up or down and it's far too quick to recover, so the aircraft just dives or stalls and hits the ground. It doesn't happen all the time but to get right to the end of a flight and then crash is very frustrating. What on earth can possibly cause that?
John
Comments
Hi,
how do you disconnect the autopilot? There are multiple ways to do that.
I'd recommend you to set up a specific hotkey for your joystick via the ini file, this never caused any issue for me.
I previously had this issue and traced it to a duplicate axis. Double check all your controls an their axis/ key commands.
I’m disconnecting via a button on my joystick linked to the autopilot disconnect command in P3D. I will investigate the double axes and report back.
I seem to recall from the old forum, using the Z key to disconnect the Q400 autopilot created a conflict with the Q400 custom autopilot. It is recommended to assign a joystick button to the Q400's AP via the ini file, or use the AP disconnect button on the glare shield, or yoke. The AP disconnect assignment is usually assigned to joystick 1, button 1 by default.
I had the same issue on my first 3 flights with Q400. In all my cases the trim tab suddenly moved to a drastic pitch-down setting, and like you, I was unable to manually pitch up in time to save the crash. I have recently been first putting the FD in STBY, (which puts the plane in pitch-hold mode) then verifying the trim is in sync before disconnecting the autopilot using the "Z" key and have had no issues. I think that pressing the "Z" key while the auto-trim is still engaged causes havoc for some reason. Must be a "Dash-ism"
Craig
Yeah, that is usually a conflict between the FSX and the external Dash auropilot. It is highly advisable to asign all flight controls and AP disconnect/trim functions via the .ini and disable the FSX AP in the aircraft.cfg. Since I did that I had no issues with the Q400.
Extraordinary, that. Thanks folks I will assign the autopilot disconnect in the .ini file instead of through P3D. Can anyone either guide me as to how to do that or guide me to a resource that’ll tell me? Never really touched the .ini file before.
BM: you say disable the FSX AP in the aircraft.cfg - how do I do that?
Thanks for your help folks
Go to your Q400 installation folder (simobjects/airplanes/mjc8q400/ini), open the ini file in notepad. Scroll down to the section labeled "joystick interface assignments."
There you should find the AP disconnect assignment already in place.
It will look something like this;
; AP DISC
J0_b0=AFCS_->inputs.AP_disengage
J0 and b0 represent your Joystick and button numbers which you want to assign to the AP disconnect function. You will have to change these numbers to match your particular control setup.
As always make a backup of the original, and your modified, ini file. In the event that you have to do a reinstall of the Q400, the ini file will be overwritten losing any changes you will have made.
Sorry Jax but can you be even more specific; it's not working at the moment and the manual is incredibly unclear. How do I know which number represents the stick I want to assign the A/P disconnect command to?
Have a look at this video, which may help you to better understand the inner workings of the .ini.
That video specifically says it's too complicated to explain. If I disable the Majestic joystick interface and just use FSX controls, will this get rid of the conflict?
Actually, sorry, I seem to have worked out the button assignment now and the A/P disconnect is working. Only problem I have now is that the trim switches, which I've also assigned in the mjc84.ini, are making the cricket bleeps and the elevator trim shut off pushbutton illuminates PUSH, but the elevator trim isn't actually moving. Is that because I have to have the elevator axis controlled by the majestic.ini too?
" ... but the elevator trim isn't actually moving. Is that because I have to have the elevator axis controlled by the majestic.ini too?"
I don't believe so. You may have a button assignment conflict. I will try to write up a more detailed description for finding and setting the correct joystick and button numbers, and post back here.
That would be excellent, Jax; I can't find any other conflict with an elevator trim assignment but at the moment, that trim just isn't moving. The key assignment is working in the mjc84.ini page, but the trim isn't actually moving. Weird.
"How do I know which number represents the stick I want to assign the A/P disconnect
command to?"
Open the Windows "devices and printers" dialog.
Right click on your controller icon, and select "game controller settings." A new window will
open showing a list of all the controllers plugged in to your pc.
begin counting from the top of the list starting with zero.
IE; For 4 devices,
Xbox 360 controller for win ..........0
logitech joystick x .........................1
saitek throttle ...............................2
saitek rudder pedals ......................3
In this example, I am going to assign the AP disconnect to my throttle quadrant which is
showing 3rd on the list but for the Q400 we have to use a value of 2. The same principle
applies to the rest of your controllers. Easy peasy.
To find the correct button number for assigning AP, TOGA, TCS, etc.
Using the same "devices and printers" dialog, right click on your controller again to open
the "game controller settings" window. Click on your controller, then the properties box at
the bottom.
In the new window, you will see the controllers axis and button test "lights" in red. Your
buttons will already be assigned numbers, but these are incorrect. As with the controller
numbering, Direct x starts counting the buttons from zero.
IE; For the saitek throttle quadrant, there are three rocker switches which give a total of 6
different buttons. In the properties window they are numbered from 1 thru 6,
but since we need to begin counting at zero, the correct numbers are 0 thru 5.
To keep it simple,
Press the button that you want to assign to the AP disconnect and subtract 1. That will be
the correct number to use in the Q400 ini.
In the ini file we would change the AP DISC line to reflect our particular controller setup.
In my example, I have assigned the AP disconnect switch to the 1st button on my throttle
quadrant.
J2_b0=AFCS_->inputs.AP_disengage
*** My instructions may be clear as mud, but the process itself is very easy peasy.
Cheers
Jax - thanks very much for that, that's not unclear - most helpful.
However, the reason I really did this was to avoid trim conflicts that cause the aircraft to pitch down/up violently after autopilot disconnect. The autopilot disconnect button works perfectly, but the trim switches don't. When I select and hold them, the crickets go off and the elevator trim shut off p/b illuminates, but the trims themselves don't move. Anyone have any ideas on how to remedy that?
BTW: when set in P3D, the trim switches work fine, but I want to avoid this weird conflict behaviour and set the trims through the mjc84.ini.
" ... the crickets go off and the elevator trim shut off p/b illuminates, but the trims themselves don't move."
The trim indicator not moving, is not something I have ever come across. Maybe Kroswynd, or Boss may have an idea as to what is causing the problem.
@rondon9898 ,
Most likely P3D's Autopilot kicks in if you were using Z to disengage via the button assignment of your joystick.
Q400 is not using FSX autopilot as such, but it will listen to the commands unless you set: AFCS_FSX_SYNC=0 in the mjc84.ini file
Sometimes for an unknown reason, FSX autopilot will turn ON on the background, despite the Q400 trying to keep it OFF at all times. After that, it will attempt to fly the airplane using the trim, as it was in your situation, which is primarily the cause for the violent pitching behavior.
Usually, the solution is:
1. Try to see if you might have another addon (navigation addon for example) that could attempt using autopilot of FSX
Do not use "Z". Use the joystick connector record in the mjc84.ini instead
Disable FSX AP link to Q400: AFCS_FSX_SYNC=0
The "crickets" sound that you speak of is actually an aural warning initiated when the elevator trim is activated for 3 seconds or more - this is designed to alert crews of a runaway trim. Possibly the best solution for you at this moment would be to assign your elevator and aileron trim assignments via P3D, which is how we initially designed the aircraft to work. This configuration can be used in conjunction with the 125 Hz controls - which is how we designed it to work and works best for those who find the .ini to be a bit of a challenge.
a. Remove the entries that you have entered for the "TRIM" within the mjc84.ini.
b. Then simply go into P3D's button assignment interface and assign the elevator and aileron trims accordingly.
Cheers
OK chaps, so trims set in P3D, and autopilot set in mjc84.ini. I’ll give it a go.