737 RNAV approach question

[Stearmandriver 2,244]

RNAV approaches are good up to a specific end/on final...then you're responsible for the landing.  Thats where your going wrong.  It's usually the last waypoint on the RNAV then it's yours.  Just checked your approach and yes after LEETS @ 7,000-RNAV stops and you fly the rest of the approach and landing without aid, just visual visual.  Gotta set your baro correctly-(Radio / 5690)-also.  Use the ILS for approach if you use VATSIM.  They-(ATC Controllers)-usually take you out of the descent path anyway to compensate for traffic, wind change etc, and it's easier to navigate

Nossir... flying an RNAV approach in LNAV / VNAV PTH provides lateral and vertical guidance to the runway threshold, and then beyond that if you go missed. You'll notice the published minimums for the approach are much lower than you'll be at LEETS; since you don't have to have any visual references until minimums, you obviously are still following guidance after LEETS.

Saw the question about IAN approach mode in the other thread; I can't personally comment on IAN since my company doesn't use it, but there's no reason this approach can't be flown in LNAV / VNAV PTH, we do that all the time.

 

Unless the AIRACS data really has been borked in the last few updates, there's something else going on. I can think of an easy way to test it; maybe somebody can try this: fly the approach, be sure to get slowed and configured early, and set your MCP altitude window to 0. This is just for testing purposes but ensures the autopilot won't level off anywhere. Then just let the autopilot drive down the glidepath in LNAV / VNAV PTH until you impact the runway. You'll crash, obviously. But that's fine; we just want to see where the glidepath intersects the runway - that'll be the point where you hit the ground. It should be somewhere in the touchdown zone. If not, the AIRACS data is bad. If you hit the ground in the touchdown zone (and not at the very end), then the approach works as is.

 

Oh, one more thing: make SURE you've got the correct altimeter setting! An incorrect setting will throw off the calculation of the entire VNAV path.

[Guest]

Nossir... flying an RNAV approach in LNAV / VNAV PTH provides lateral and vertical guidance to the runway threshold, and then beyond that if you go missed. You'll notice the published minimums for the approach are much lower than you'll be at LEETS; since you don't have to have any visual references until minimums, you obviously are still following guidance after LEETS.

Saw the question about IAN approach mode in the other thread; I can't personally comment on IAN since my company doesn't use it, but there's no reason this approach can't be flown in LNAV / VNAV PTH, we do that all the time.

 

Unless the AIRACS data really has been borked in the last few updates, there's something else going on. I can think of an easy way to test it; maybe somebody can try this: fly the approach, be sure to get slowed and configured early, and set your MCP altitude window to 0. This is just for testing purposes but ensures the autopilot won't level off anywhere. Then just let the autopilot drive down the glidepath in LNAV / VNAV PTH until you impact the runway. You'll crash, obviously. But that's fine; we just want to see where the glidepath intersects the runway - that'll be the point where you hit the ground. It should be somewhere in the touchdown zone. If not, the AIRACS data is bad. If you hit the ground in the touchdown zone (and not at the very end), then the approach works as is.

 

Oh, one more thing: make SURE you've got the correct altimeter setting! An incorrect setting will throw off the calculation of the entire VNAV path.

Sorry for the mis information then.  Just had similar issues when attempting RNAV landings and eventually just returned to ILS landings.  You are a company pilot and know more than me.  I'm currently learning more about such things via AoA and 737 course study.  Read the manual but still tough to ascertain all the right moves so off to class I go!...

Sorry for the mis information then.  Just had similar issues when attempting RNAV landings and eventually just returned to ILS landings.  You are a company pilot and know more than me.  I'm currently learning more about such things via AoA and 737 course study.  Read the manual but still tough to ascertain all the right moves so off to class I go!...

And thanks for the info!, always ready to learn!  Hate the mistake tho, I should know better by now!, was not really sure just basic input.

 

"Oh, one more thing: make SURE you've got the correct altimeter setting! An incorrect setting will throw off the calculation of the entire VNAV path."

 

I was also going to add a comment on his altimeter/baro part

Still prefer to be vectored in and use ILS... :smile:

[Stearmandriver 2,244]

Hah no problem Don, and I'm sorry if I came off as flippant.  Didn't mean it that way at all, was just typing fast.

 

Believe me, confusion about this stuff is common even in the industry.  In the first place, Boeing delivers these planes with lots of different options, creating different ways of flying this stuff (reference the IAN modes that I know nothing about), and then different airlines use different procedures for the same approach even when using the same equipment.  You can find a few different techniques discussed just on this thread; none is better than the other, they're just the way different airlines do it.  So plenty of confusion to go around ;-).

[scandinavian13 5,192]

and eventually just returned to ILS landings.

 

ILS approach.

 

What follows is either a hand flown (manual) landing, or an autoland. The technology used for the approach and the technology used for the landings should be treated separate concepts. Autoland, while not currently approved for this use, could also be used at the end of a GLS approach.

 

Sorry - I know that seems pedantic, but people's use of "ILS landings" contributes to the misconception that autolands are the norm, and that ILSs usually/always end with one.

[Guest]

ILS approach.

 

What follows is either a hand flown (manual) landing, or an autoland. The technology used for the approach and the technology used for the landings should be treated separate concepts. Autoland, while not currently approved for this use, could also be used at the end of a GLS approach.

 

Sorry - I know that seems pedantic, but people's use of "ILS landings" contributes to the misconception that autolands are the norm, and that ILSs usually/always end with one.

Thanks for the info Kyle!  Already bookmarked!

 

I know ILS approaches don't always have autoland feature, I personally don't use unless necessary say @ SFO / fog w/rnwy 28R.

One should NOT use ILS for autolands unless needed.

Even if/when available I go with the LOC approach, not the Cats, really works best for vectoring on VATSIM.

[Guest]

Hah no problem Don, and I'm sorry if I came off as flippant.  Didn't mean it that way at all, was just typing fast.

 

Believe me, confusion about this stuff is common even in the industry.  In the first place, Boeing delivers these planes with lots of different options, creating different ways of flying this stuff (reference the IAN modes that I know nothing about), and then different airlines use different procedures for the same approach even when using the same equipment.  You can find a few different techniques discussed just on this thread; none is better than the other, they're just the way different airlines do it.  So plenty of confusion to go around ;-).

No problems.  I like learning, if I state something incorrectly I prefer to be corrected!

[cubs 2]

I just did this approach with no problems. Before your initial fix (QWIKE) or (CLFFF), the aircraft needs to be at flaps 1 or more.

This will keep the aircraft in VNAV PATH. As you approach LEETS, you should be at flaps 25 for a stable approach and do not set your missed approach alt until your below your FAF of 300 feet.

 

hope this helps!

[jrw4 624]

I tried this approach yesterday using IAN as I lamely reported in the wrong thread.

 

To address Stearmandriver's suggestion regarding flying the approach down to the runway just to see where one lands, I think I did the next best thing. At around 800 AGL, I dropped the HUD into position. The guidance cue and flight path vector were centered around 1500 feet down the runway, which is a bit further from the threshold than a typical ILS approach. So there doesn't seem to be a problem with AIRAC 1513, at least.

 

And, yes, it is necessary to keep the speed under control from the IAF inward. KDEN is higher than most airports, so things feel even more slippery than they do closer to sea level.

 

John

[ExNusquam 11]

So I went and tried stearmandriver's suggestion, at least until the autpilot leveled off at 50'. Otherwise, the airplane was perfectly land-able down to minimums.

 

I shot both the RNAV Y and Z, you can watch them here:

 

I think most of your confusion is explained away by this chart note:

 

You are supposed to be above the PAPIs on the RNAV glidepath (and the ILS GP as well, as far as I can tell).