One for the 737NG experts out there!

 

As we know, it's possible to pre-arm the LNAV and VNAV modes on the ground in our beloved NGX.

 

But I thought that this was not possible on the real 737NG ?

 

......... or is it the case that the 300/400/500 series did not have LNAV/VNAV prearming on the ground, but the NG always has?

 

... or maybe it's an airline option?

 

Would be interesting to hear (knowledgeable, rather than guesswork) views. :smile:

I am not a pilot, but remember this being discussed on the PMDG forum relating to theFS9 version....this was before the FSX version had been launched.

 

Input at the time from real pilots was that the real NG could arm LNAV on the ground and this was modelled in the sim.

 

VNAV was different. The original real NG could not be VNAV armed, but the FMC manufacturer did bring out a software update to allow it. It was problematic and some airlines forbade its use and Boeing did not recomend it. I think this was why the FS9 version has no VNAV arming.

 

Later apparently the software problems were sorted and the real NG could be VNAV armed on the ground. This is why the FSX version has this function modelled.

 

Please remember I am not a pilot, but this was input from real pilots who flew the NG. I hope this helps, and would welcome input from real pilots who can either confirm this ...or tell me i am talking rubbish

 

Peter

either confirm this ...or tell me i am talking rubbish

 

You're right. LNAV (first waypoint must be within 5 degrees of takeoff runway heading) and VNAV can be armed (there is no prearming) before takeoff.

 

Little note on LNAV however. If you are cleared to "fly runway heading", takeoff and then select HDG SEL after takeoff. If you are cleared to follow a DP (also known as SID), you can select LNAV before takeoff to lighten the workload a bit.

No pre arm on the Classics. NG with FMC version U10.7 and earlier, no VNAV but yes LNAV. U10.8 was the problematic version and U10.8a corrected some of the problems so you can arm VNAV on the ground.

Ah thanks Matt, that clarifies that the ability to prearm LNAV/VNAV is related to the FMC version.

 

Cool. :smile:

I have got this Blu-ray and you can see they arm LNAV and VNAV in the 737-800 before takeoff !!

 

Great blu-ray I can recommend this one !

 

 

Air Austral Boeing 737-800, 777-200LR & 777-300ER [blu-ray] (2012)

 

 

http://www.amazon.com/Austral-737-800-777-200LR-777-300ER-Blu-ray/dp/B008E8WIHS

 

Robert

It's technically related to both the FMC revision and the MCP firmware revision I think - we modeled the latest available stuff when we made the NGX, so it has it.

Hmmm, I thought this was something to do with MCP, namely that Honeywell couldn't prearm VNAV and Collins could prearm both.

@ 08:26 both VNAV and LNAV are armed, then @ 08:50 LNAV isn't armed.


The cleared alt for no LNAV is 5000f (changed from 10000). Also the course has changed.

An amended clearence. So they turned off LNAV for this.

I love these videos, I must buy them.

 

@ 08:26 both VNAV and LNAV are armed, then @ 08:50 LNAV isn't armed.

NGX does the same thing. At 400' (I think) it lights up again.

 

Noticed they have also that thing installed on the plane, that lady who warns about things.

NGX does the same thing. At 400' (I think) it lights up again.

 

It does when the TOGA is on but you can see clearly that it has been switched off in this video, well before take off.

Many thanks Ryan and all for the info and explanations ........ very interesting stuff. :smile:

 

PS...... I have a number of Just Planes DVDs for the NG, but not that Air Austral one; it looks great!

 

PPS...... It surprises me that on a lot of the Just Planes DVDs, the crews take off without use of flight director. On the Solbelair 737-800 DVD almost all of the departures are without FD in use; with the pilots manually pitching for IAS in the climb, and tracking the SIDs purely using the ND. (Using A/T for TOGA, then calling 'N1').

No pre arm on the Classics. NG with FMC version U10.7 and earlier, no VNAV but yes LNAV. U10.8 was the problematic version and U10.8a corrected some of the problems so you can arm VNAV on the ground.

 

As far as I recall off the top of my head, our beloved NGX displays version 10.8, the "problematic" version.

Any chance we can get this updated to 10.8a with SP2

NGX already has 10.8A.

Hmmm, I thought this was something to do with MCP, namely that Honeywell couldn't prearm VNAV and Collins could prearm both.

It's technically related to both the FMC revision and the MCP firmware revision I think - we modeled the latest available stuff when we made the NGX, so it has it.

Tabs is correct. Both Collins and Honeywell can do T/O with VNAV armed, you need to have U10.8a and CDS & MCP updates.