SearchSearch 

VNAV?

Pro Member Captain
Jared Captain

So on the Pmdg 737's there is the VNAV button. this doesnt make sense. ill turn it on once i get to cruising altitude. but when i start to decend, the engines go idle and the plane pitches down to maintain the speed indicaded in the legs page. so if i put the spoilers down, the plane pitches down so far so it can keep a certain speed. i thought it was supposed to follow a certain descent rate to pass the waypoints at the selected altitude in the LEGS page in the FMC. is anyone else having this problem?

4 Responses

Pro Member Captain
Zach (ranald) Captain

Yes! the PMDG 737NG does seem to have the problem of not getting to the waypoints at the cerrect altitude but will often arrive at the next waypoint at the cerrect altitude.LDS 767 haad the same problem I think and they released a fix but PMDG have not 😕 Why do you turn on you VNAV when you reach cruise ❓ I turn mine on at about 1000-1500 feet.

Pro Member Captain
Jared Captain

well it turn it on at cruise cause depending on the conditions at cruise like if you have a head or tail wind, the fmc automatically puts in a good mach # that the FMC follows when the VNAV is on. so u dont have to adjust the mach # in the speed hold. cause when you turn on the VNAV, it clears the speed hold box and it goes clear. so the only good thing is that it hold a certain speed for certain conditions at crusie

Pro Member First Officer
Greg (FL050) First Officer

Jared wrote:

well it turn it on at cruise cause depending on the conditions at cruise like if you have a head or tail wind, the fmc automatically puts in a good mach # that the FMC follows when the VNAV is on. so u dont have to adjust the mach # in the speed hold. cause when you turn on the VNAV, it clears the speed hold box and it goes clear. so the only good thing is that it hold a certain speed for certain conditions at crusie

Actually, if you look in the FMC you adjust all these figures. Mach Cruise is set in the FMC and is default .80. The 737 can actually cruise at .82.

VNAV is Vertical Navigation and Speed

Pro Member First Officer
Martin (Blake14) First Officer

I didn't know that the autopilot could do the descents exactly on the waypoint. I have always done it by steering manually and giving the autopilot a fixed descent rate.

All times are GMT Page 1 of 1

Related Questions