Hi Everyone,

 

First,Im sory for my bad english..

 

I'm using Sp1c Pmdg NGX and I have a problem with LNAV.

 

After takeoff, I am activating VNAV,LNAV and A/P.Airplane is following LNAV path normal and smoothly.But after 5-10

minutes later,LNAV is deactivating and airplane leaving from the LNAV path.After this, I am trying to use heading for

correction, but airplane is not responding to my commands :S Can someone help me about this situation?

 

 

For information :  Im using FSX default weather engine (updating every 15 min)

 

its maybe about weather update ??

 

Best Regars.

 

 

 

No it's a problem with your NGX. Is VNAV working properly?

Yes usually working properly but somethimes when I activate (after take off) not working properly..

 

For this situaition, I uninstalled pmdg and reinstalled.But I had LNAV problem in my first flight.

 

Thank you for your fast answer..

Could it be spikes sent by your yoke or joystick? Have you tried re-calibrating and adding small null zones to each axis?

 

What does your PFD/FMA read after LNAV disengagement? Could it be that LNAV is manually overridden?

I am using Logitech Pro 3d joystick and yes I have calibrated..and I set small null zones for each axis.

 

I havent got any error messages on FMS or PFD when LNAV disengaged..

 

But I remember, when I enter to runway for takeoff, I saw recall lamps is on :S (I mean warning lamp)

 

After, I checked FMS,PFD and recall ..But nothing..No error messages and warnings.

 

I am wondering, what is the relation with FMS and joystick? Can you explain please?

 

For information,  Im sure my FMS setup is correct (SID,Performance,Route etc.)

 

Thanks..

The pilots can override the autopilot without switching it off. There's also a mixed mode available where VNAV remains engaged, while LNAV is replaced by control column inputs (called CWS, Control Wheel Steering).

 

So, if your joystick isn't centered, or if it spikes, or if you apply manual pressure on the joystick, LNAV may disengage.

 

The current A/P mode is indicated on the PFD, including CWS. I don't think your issue is related to the FMC or to the preflighting procedure, though.

 

For a test, have you tried setting A/P behaviour to 'not realistic' or switching the joystick off after A/P engagement? (hotkey Ctrl+J or similar - have to recall that from memory)

Hello again,

 

Thank you very much your fast answers.

 

Yes ,I understand..You're right, its maybe about my joystick..I will try your solutions tonight

 

I mean I will deactivate my joystick after A/P engagement..

 

Thanks again..

any idea???