engaging FMS and HDG w/NAV does not track flight plan in GPS - any ideas?

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jerel2k6:
I would like some help on this issue.  I am engaging HDG button and the NAV button (above APR button).  This gives me LNAV(wht) HDG <--- ALT ASEL.  I am in climb when I engage this.  It is to my believe per introductory flight that this should work before cruise.  The aircraft is drifting off the flight plan.  Any ideas on why this occuring.  I am using the default GPS. 

I have received several e-mails and responses that HDG and NAV buttons cannot be on at the same time for this to work.  I am confused about a resolution.

A real ERJ pilot indicated this as well.  Both HDG and NAV cannot be engaged.  It is one or the other.  I was thumbing through some documentation on the Feelthere ERJ and their FMS shuts off the HDG button once FMS is engaged to track the flight plan. 

I am using Bills' panel with the Dreamwings ERJ package (charles fox).  It is an excellent package.  I am just finding some things that are not explained as issues in the manuals that are included with that package and the erjproject@yahoo.com support e-mail address is down.

Thanks for your help.

Bill_Grabowski:
The usual method for takeoff is to ...

-- Load a flight plan, which should be seen in the MFD nav display, with your plane in takeoff position ready to go to the first waypoint. 
     IF... you have pushed the FMS button on the display control panel, text on the PFD and ND will turn magenta. That means it's tracking the flightplan.
     IF... you then push the NAV on the autopilot panel, "LNAV" will appear to the left of the arrow on the PFD, indicating that you have captured the flightplan route and the autopilot will fly the plan if you push the AP button. But don't push any buttons yet.
-- Push the FD1 button to make the flight director appears.
-- Push the TOGA button on the throttle. The FD will pitch up to 14 degrees for takeoff and a green "ROL" will appear to the left of the couple arrow at the top of the PFD to indicate roll control.
-- Takeoff and pitch up to 14 degrees. After you've retracted gear and flaps, you have to make some decisions:
     1. Your present vertical mode is "TO" (takeoff). You can hand fly to your target altitude or select a climb mode, either SPD, FLC, or VS. Once you've done this, the vertical mode will appear in green (active mode) and the armed mode "ASEL" will be white. If you then deselect one of the vertical modes, a green "PIT" will appear meaning pitch mode (except for some reason SPD mode which goes to ASEL, which I can't explain).
     2. Do you want the autopilot to fly your flightplan or do you need to engage a heading? If flightplan, push the FMS button on the DCP, then the NAV button on the autopilot panel to engage and a green "LNAV" will appear on the PFD. If you have pushed the AP button to engage the autopilot, the autopilot should follow the flightplan. If you push the HDG button, "HDG" will appear and you'll follow whatever heading you have dialed in. If you reengage the NAV button, "LNAV" will reappear and the autopilot will resume following the flightplan route and attempt to intercept the course for the next waypoint.

If you are in FMS mode (with magenta text and bearing indicators), if you push HDG button, the NAV button illumination will extinguish, and vice versa. If you are in NAV mode (NAV button pushed on DCP and tracking VOR's and localizers instead of the flightplan, with text and bearing indicators in green), HDG and NAV modes can coexist with both buttons lighted. For instance, if you want to intercept a localizer (or a VOR radial), you select an active HDG mode (green annunciation on PFD) and arm the APR mode (white "LOC" annunciation) with both illuminated HDG and NAV buttons. When the localizer or vor radial is intercepted, then the HDG mode will terminate and indicators extinguish, and LOC (or VOR) becomes the active mode with the APR (or NAV) button still illuminated.

Bill

jerel2k6:
Problem solved!   

An earlier discovery on the docs or forum indicated having to disengage and engage the FLC or vertical mode to change flight levels from a previously set altitude.  This is the same as the LNAV mode (GRN) following the flight plan.  When I takeoff I am in FMS mode.  I have to disengage and engage FMS by selecting NAV then back to FMS and then it works!


engage NAV   LNAV (white)
engage NAV-engage FMS  LNAV <-- VS(GRN)   ASEL(wht)    climbing  FOLLOWING FLIGHT PLAN

*** at this point I noticed YAW DAMPER did not engage after takeoff when I engaged AP.  I attempted to engage YD just to try but this disengages the LNAV mode.   I engage BNK before takeoff and this may affect YD?!?  Any ideas?

LNAV <--- ALT (GRN)  cruise   AS EXPECTED and FOLLOWING FLIGHT PLAN

Happy New Year!

Thanks!

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