PMDG 737-700 RNAV approach

[Fiorentoni 4,156]

22 minutes ago, SAS443 said:

What is more prudent is to set the MCP to DA(H) or MDA(H) approximately 2 NM before the FAF to prevent level off at platform altitude. 

When the airplane is at least 300 feet below the missed approach altitude and stabilized in VNAV PTH, set the MCP to the missed approach altitude.

No need to dial altitude down to zero, just spin the alt knob quickly.

 

Example: FAF is 3000 feet, DA is 500 feet, MAP alt is 4000 feet. When I descent in VNAV PTH and am at let's say 2000 feet and I turn the altitude selector up to the MAP alt (4000 feet) - wouldn't the plane go into ALT ACQ mode once I "pass" 2000 feet during the turn of the knob up to 4000? Or will it ignore it if I turn the knob quickly enough?
If so, to what altitude will it descend then? The DA of 500 feet? Or unlimited?

[SAS443 1,716]

21 minutes ago, Fiorentoni said:

Or will it ignore it if I turn the knob quickly enough?

exactly it will continue in VNAV PATH

 

21 minutes ago, Fiorentoni said:

If so, to what altitude will it descend then? The DA of 500 feet? Or unlimited?

VNAV path guidance transitions to level flight once the missed approach fix is passed

[rjquick 219]

1 hour ago, Cpt_Piett said:

Flying the mentioned approach in this thread, when I look at PROG page 4, the actual RNP is 0.06nm. 

That is good. I noticed a typo in my post as said RNP approaches are usually 0.4, I meant to type 0.1. So, 0.06 is still good. If you tighten the limit on that page you'll see range narrow on the display so you can see graphically how the autopilot is doing.

[Stearmandriver 2,244]

There are actually quite a few differences between flying an RNAV approach in LNAV/VNAV vs IAN.  One of the largest has already been mentioned: IAN is for straight in approaches. A curving approach, especially an RNP (AR) with RF legs, cannot be flown in IAN, which is why most airlines do not use this mode or even have it. 

Different airlines take different approaches to setting an MCP altitude. Some like to set mins, and then "spin through" current altitude up to the missed approach alt once field is in sight or when approaching mins. The threat here is that the flight guidance might capture current altitude, destabilizing the approach. 

Another option is to set field elevation in the MCP when cleared for the approach (actually you round down to the hundred foot setting below field elev) and leave it there for the landing. If you miss, you have to get the MCP alt set on the go-around.  We tie it to the "gear up" call. 

Functionally, it does not matter which method you pick, they both work fine... it's just good to understand why you're doing it that way ;).

Edited July 29, 2022 by Stearmandriver