27 minutes ago, kevinh said:

If it was about aircraft size the 747-8 wouldn’t need a VSD or IAN but it has them. No doubt the 777X will have it too. Having a VSD improves terrain awareness for any aircraft. So there is no reason not to have improve display features or enhance the navigation system in a new or upgraded design.

sure... there is no reason why not to put in a function that is available.. I just meant that there was likely no requirement for the VSD when the 777 has been developed and they first came to that point when they thought about the NG's capabilities.. Use what you have but don't waste money on things you don't "need".. 

2 hours ago, Ephedrin said:

sure... there is no reason why not to put in a function that is available.. I just meant that there was likely no requirement for the VSD when the 777 has been developed and they first came to that point when they thought about the NG's capabilities.. Use what you have but don't waste money on things you don't "need".. 

I think it's more likely to do with availability of technology than a requirement for the 737NG. After all the 737 Classic had operated without a VSD since the 1980s. Airbus first put a VSD on the A380.

Edited March 19, 20188 yr by kevinh

Boy,  makes ya wonder how the old propliner guys managed a descent without VNAV, a VSD, green banana etc...

... or,  not.  The simple answer is they were aviators,  not just computer programmers.  ;-)

Don't get me wrong,  all these tools have value (and some are mandated to be used in different phases of flight by different operators,  and I do follow my operator's guidance IRL)... but there's a difference these days.   It used to be that you learned the basics first and then started learning to incorporate the tech.  Now,  it seems even primary students are learning to place too much reliance on toys,  instead of stick/rudder/energy/sight picture flying.   (A 737 can be flown as effectively that way as a Super Cub can).  I'm talking in real life too,  not just the sim.  One thing I find interesting about flight sim is that it's gotten so realistic,  real - life human factors concerns are popping up in the sim world too.   That's... kinda cool! 

Ok,  sorry for the tangent.   Back to your original question.   I'm unsure as to whether you were trying to fly an RNAV approach or just a descent,  but either way you do not need to select APP.   You CAN, if flying an approach,  and a special mode called IAN will activate,  but not all operators have this in reality.   The plane will fly the descent path in LNAV/VNAV PTH happily,  though.  You can do even the tightest-tolerance RNP approaches this way.   But you have to do one thing I didn't see mentioned - did you reset your MCP altitude?  If for instance you're at 4,000 ft when you intercept your descent path,  you have to reset your MCP to something lower or the plane won't start down.  Even in VNAV, the MCP altitude is always honored.   Different operators deal with this in different ways for RNAV approaches... ours is simply to set field elevation in the MCP as soon as we're cleared for the approach and in VNAV PTH.

Speaking of RNAV, does anyone have any tips on getting the aircraft to descend while still in VNAV on the approach past the IAF when NOT fully configured.

It seems like the aircraft will not descend on the approach until you are fully configured for landing.

Been trying to figure this one out for a while now.  All the videos I've seen start out with someone holding at 6000' or so then starting their approach from there.

I would think it would be ok not to be dragging your flaps and gear all over town while still trying to fly another 50 or so track miles of approach.

Thanks.

Assuming you have the MCP altitude set correctly I think the only thing which will stop it descending is if you are in VNAV SPEED. It needs to be in VNAV PATH otherwise it will use pitch to control speed and not descend on the glide path. 

Edited April 2, 20188 yr by kevinh