what a perplexing situation. Well thanks for your help Leffe. Oh and yes if I manually press the LNAV button after takeoff it will stay lighted, it's just the after takeoff procedue that is giving me the trouble.Devin Mack

Same problem happends over there, actually I disappointed from all those Flight-Sim payware addons.I have also expected gauges FREEZE in VC, seems like PMDG saving money to perform good QA.I work in software development Industry and I know exactly how those parts are working.It is disappointing to see how they brawely release SP1 with many bugs, and everybody says they're genious, maybe they just the best of worse but not more.I'm not familiar with real aircraft systems, but details of PMDG are really impressing, the only problem is a quality and bugs.

what a perplexing situation. Well thanks for your help Leffe. Oh and yes if I manually press the LNAV button after takeoff it will stay lighted, it's just the after takeoff procedue that is giving me the trouble.Devin Mack

looks like a weird situation.first thing i wanted to suggest is to change the PFD display layout but you've already tried that.1.What happens if you set the autobrakes OFF (currently still RTO) and the landing gear the the OFF position?2.You're taking off with FLAPS 1 and when airborne they are 5 or do i misinterpret the screenshots?3.Are you able to reproduce this issue when using another route/SID ?

At least from what I know, only LNAV is armed on gnd.VNAV suppose to be engadged passing 400 AGL and it will be armed passing 400 AGL only.And light bolbs can be burned, FMA is the only place to look for what the AC is doingand his mode.

And light bolbs can be burned

Not the issue here as he clearly states he can press it to come alive manually,The issue is why it doesn't appear lit automatically like the VNAV button

Not the issue here as he clearly states he can press it to come alive manually,The issue is why it doesn't appear lit automatically like the VNAV button

Didn't say this is the issue. Just said that when you fly, MCP lights are not where you should look tosee which mode is on.FMA is the place.

Have the same problem - thought it was me but perhaps not.To add to the above.1. Pre - TO. Select LNAV on MCP - it arms {white on FMA}2. Post TO. LNAV engages correctly {green on FMA} but LNAV light on MCP extinguishes.3. Climb/Cruise. LNAV remains engaged {green on FMA} and follows correct route - LNAV MCP light remains out4. At any stage - press LNAV on MCP: LNAV disengages and AP reverts to CWSR5. Press LNAV again and LNAV re-engages and reverts to normal operation.As with the OP could not find this in FCOM or tuuorial so perhaps some of our experts could advise as they do not see it- is it something in my NGX set up?John Rooum

looks like a weird situation.first thing i wanted to suggest is to change the PFD display layout but you've already tried that.1.What happens if you set the autobrakes OFF (currently still RTO) and the landing gear the the OFF position?2.You're taking off with FLAPS 1 and when airborne they are 5 or do i misinterpret the screenshots?3.Are you able to reproduce this issue when using another route/SID ?

Thanks for your ideas Antoine, sadly I tried them all and the event still occurs regardless of my takeoff config, local, or SID. Oh and the flaps had been different in the screen shot because in the original ones I took while on the ground with flaps 1 I had forget to take a screenshot in the air so I restarted the flight and changed the weights a little to set flap 5, either way the issue still persists.

Have the same problem - thought it was me but perhaps not.To add to the above.1. Pre - TO. Select LNAV on MCP - it arms {white on FMA}2. Post TO. LNAV engages correctly {green on FMA} but LNAV light on MCP extinguishes.3. Climb/Cruise. LNAV remains engaged {green on FMA} and follows correct route - LNAV MCP light remains out4. At any stage - press LNAV on MCP: LNAV disengages and AP reverts to CWSR5. Press LNAV again and LNAV re-engages and reverts to normal operation.As with the OP could not find this in FCOM or tuuorial so perhaps some of our experts could advise as they do not see it- is it something in my NGX set up?John Rooum

John it's comforting to know that someone else is having this issue as well, I just wish we could get someone from the PMDG team to give their take on it though.Devin Mack

Same problem here (since SP1). LNAV mode _is_ active, but not lit. Switching LNAV off and on again during flight usually brings it back.Regards,Jörn

I have the same problem, I noticed, thought it didn't bother me much, that if I engaged both VNAV and LNAV on the ground, that sometimes after I press TOGA, LNAV would extinguish.I would usually repress the button after takeoff, before I engage AP, but that would sometimes disengage VNAV (as I remember!). In the end, a click here and there would solve the "situation".But: sometimes it all went normal, 2 are on, two are kept on, and I only press AP.The situation I was testing was a saved flight from EGKK to LOWI, always the same config, and I always take care that I have right configuration on takeoff, along with correct trim and following the FD anyway possible, usually between 15 and 20 degree up. With the exactly same procedure, sometimes it happens and sometimes not. Maybe I am missing something, but I think not.

Have the same problem - thought it was me but perhaps not.To add to the above.1. Pre - TO. Select LNAV on MCP - it arms {white on FMA}2. Post TO. LNAV engages correctly {green on FMA} but LNAV light on MCP extinguishes.3. Climb/Cruise. LNAV remains engaged {green on FMA} and follows correct route - LNAV MCP light remains out4. At any stage - press LNAV on MCP: LNAV disengages and AP reverts to CWSR5. Press LNAV again and LNAV re-engages and reverts to normal operation.As with the OP could not find this in FCOM or tuuorial so perhaps some of our experts could advise as they do not see it- is it something in my NGX set up?John Rooum

This is identical to the behaviour of mine as well!

I also have this problem. Only since SP1Apologies. Forgot my signature. Mark McNulty

Yep, same problem here.

Just for the statistics: +1. Lnav light extinguishes but lnav keeps engaged.

One more here with the LNAV active but not lit problem.