54 minutes ago, Christopher Low said:

....and yet Bilal2104 is saying exactly that, and he states that he is a real world 737 pilot??

Well that's why I'm asking.  What would be the point of selecting VOR/loc first, if you're cleared for the approach and thus intend to track both the localizer and glideslope?  In our 737s (and every other airplane I've ever flown) the glideslope will not capture before the localizer, and so there's no danger of starting down before established on the loc.  But like I say, some of these "truisms" in the sim world do come from somewhere and so I'm curious if anyone actually does it this way and why.  (But also, a lot of these truisms seemingly originated out of thin air, so it always makes me wonder.)

34 minutes ago, Stearmandriver said:

Well that's why I'm asking.  What would be the point of selecting VOR/loc first, if you're cleared for the approach and thus intend to track both the localizer and glideslope?  In our 737s (and every other airplane I've ever flown) the glideslope will not capture before the localizer, and so there's no danger of starting down before established on the loc.

Maybe the procedure is a carryover from older aircraft that didn't protect against capturing the glideslope before the localizer? (Do you know how the 737 Jurassic behaves in this regard?) When newer aircraft were introduced, operators with mixed fleets may have retained the old procedure for commonality; at some point, the old aircraft that required the procedure were phased out, but the procedure was never changed?

Just an idea...

3 hours ago, Stearmandriver said:

Well that's why I'm asking.  What would be the point of selecting VOR/loc first, if you're cleared for the approach and thus intend to track both the localizer and glideslope?  In our 737s (and every other airplane I've ever flown) the glideslope will not capture before the localizer, and so there's no danger of starting down before established on the loc.  But like I say, some of these "truisms" in the sim world do come from somewhere and so I'm curious if anyone actually does it this way and why.  (But also, a lot of these truisms seemingly originated out of thin air, so it always makes me wonder.)

The reason that I started doing it that way is because that's what is stated in the PMDG 737 tutorial!

9 minutes ago, Christopher Low said:

The reason that I started doing it that way is because that's what is stated in the PMDG 737 tutorial!

Me too! 

From actual ummm pilots:

https://www.pprune.org/archive/index.php/t-419161.html

To avoid false captures it is good practise to go first for VORLOC and once you are established on LOC and within 10nm to arm the glide.

If you are joining within 10nm it is usually OK to go directly for the APP mode, there might only be ATC issues - like in the UK, where you are first cleared for the localizer and once you reported established, you are cleared for the ILS.

Using FSHUD I always get "report when established on localiser" before being cleared for approach. 

Versatilty is a skill. 

5 hours ago, Christopher Low said:

....and yet Bilal2104 is saying exactly that, and he states that he is a real world 737 pilot??

Sorry for the late reply,

 

The reason why "we" do this procedure is to align the aircraft with the centerline (VOR/LOC) first before we initiate decent on the G/P.

5 hours ago, Christopher Low said:

....and yet Bilal2104 is saying exactly that, and he states that he is a real world 737 pilot??

Sorry for the late reply,

 

The reason why "we" do this procedure is to align the aircraft with the centerline (VOR/LOC) first before we initiate decent on the G/P.

2 hours ago, Bilal2104 said:

Sorry for the late reply,

 

The reason why "we" do this procedure is to align the aircraft with the centerline (VOR/LOC) first before we initiate decent on the G/P.

But the aircraft won't capture the glide until after capturing the loc in approach mode, so where does the concern stem from about a false glideslope capture? 

3 hours ago, sloppysmusic said:

Me too! 

From actual ummm pilots:

https://www.pprune.org/archive/index.php/t-419161.html

To avoid false captures it is good practise to go first for VORLOC and once you are established on LOC and within 10nm to arm the glide.

Really makes me wonder if there are 737s out there that are configured differently than the ones I (and all of my friends at US airlines) fly.  I do not understand why you would have an airliner configured to be able to capture a glideslope before a localizer though; there is never a time when you would want to do that.  Even the Brasilias I started on almost 30 years ago wouldn't do that, and I've never taught anyone on OE in any airplane to arm VOR/Loc unless that's actually the thing you want to do -track the loc and not the glideslope.  

There are times when that's what you want to do, so of course there are times to use that mode.  But also, it's a recipe to forget to subsequently arm approach and destabilize yourself by not realizing it until you go high.  Versatility is certainly a skill, but so is understanding what your airplane will and won't do 😉.  I'm also not sure I'd take a video game tutorial as gospel here; who knows who wrote that and if they even understood why.  Could be as simple as they tried it that way and it worked, so that's what they wrote in the instructions...

1 hour ago, Stearmandriver said:

Really makes me wonder if there are 737s out there that are configured differently than the ones I (and all of my friends at US airlines) fly. 

...

1 hour ago, Stearmandriver said:

I'm also not sure I'd take a video game tutorial as gospel here; who knows who wrote that and if they even understood why.  Could be as simple as they tried it that way and it worked, so that's what they wrote in the instructions...

The tutorial I tried to use was DOWNLOADED from the PMDG website. It was written for the 737-700.

PMDG tech support said I can use the same tutorial for the 600 and the 800... So perhabs@Stearmandriver has a point. Not only are airlines configured differently but different variants of the 737 are different too at least in as far as PMDG and IRL auto-land procedures are concerned. These undocumented differences and 'truisms' make it difficult for the newbie to learn an already complicated procedure for auto-landing the aircraft.

I mentioned that I tried to use the tutorial. I used the word "tried". There is a reason for that. The tutorial has instructions to follow a VECTOR along the planned route. Towards the end of the route the ATC cleared me to a new waypoint and increase my altitude from FL340 to FL410 which did not make any sense. Why? See graphic below. 

Also, the route's general direction is southward from KPDX to KSFO for a landing to KSFO's northward facing 28R. The default ATC then tells me to head north to 015 and AWAY from my final airport destination when I'm close to arriving at the airport and I've been heading southwards all along towards KSFO's 28R.

The advice here in Avsim was to ignore the DEFAULT ATC. The problem with that advice is the newbie struggling how to make sense of how this whole thing works apparently has three different choices: BeyondATC, SayIntentions and FSHUD. There's actually also a 4th choice. Upgrade to the default ATC in MSFS 2024 (which might be improved in some future iteration of MSFS 2024?).

Back to the subject of auto-landing. From the posts above, it seems to me that there are three choices to auto-land the aircraft:

1. Use VOR/LOC and then APP
2. Use APP and then VOR/LOC
3. Ignore VOR/LOC and just use the APP

Do I have the tutorial and auto-land all wrong?

---

 

I do not think that Option 2 is a valid choice. As far as I am aware, you would always want to capture the VOR/LOC signal before APP.

36 minutes ago, anavsun said:

2. Use APP and then VOR/LOC

Never! Unless told to go around/missed approach to a VOR radial.

32 minutes ago, Christopher Low said:

I do not think that Option 2 is a valid choice

It's not unless above!

36 minutes ago, anavsun said:

The advice here in Avsim was to ignore the DEFAULT ATC

Ignore ALL ATC completely when learning the ac. Except when confident enough to switch nav modes on the fly at a moments notice!

1 hour ago, Stearmandriver said:

Really makes me wonder if there are 737s out there that are configured differently than the ones I (and all of my friends at US airlines) fly.

The classics behave differently apparently and there are many differences between FMS firmware updates throughout NG/Max lifetime. The PMDG does not use a specific version it 'borrows' features from others. The PMDG FMS can allow/disallow glideslope capture BEFORE LOC intercept which is a feature of some of the 'live' FMS versions too. 

1 hour ago, Stearmandriver said:

I do not understand why you would have an airliner configured to be able to capture a glideslope before a localizer though; there is never a time when you would want to do that

Seeing as you have to TELL the FMS to disable or enable that function it would seem to be an SOP not a regular choice by the PILOT.

One scenario I could possibly imagine is if you are too high on your approach (hello VNAV!) and above alt restrictions for the approach (and terrain not an issue!) then capturing and following GS early would help you to descend to 'catch up' to FAF. ATC would have to authorize of course. It's safe as long as you remember to go back to ALT hold once at intercept height if still not on LOC intercept. Of course it's safer to just alter your V/S or descent angle manually to get down........

Sounds a recipe for disaster but I hear WAY worse from US ATC all the time these days...

 

Edited February 8, 20251 yr by sloppysmusic
tippo

28 minutes ago, Christopher Low said:

I do not think that Option 2 is a valid choice. As far as I am aware, you would always want to capture the VOR/LOC signal before APP.

Yes. On second thought you are correct. There's no point in selecting VOR/LOC when you already have lateral and vertical guidance. 

There's something else. No one has mentioned using speed brakes in this conversation. I'm wondering when that is used. For speed brakes is there a difference between arming it and activating it?  If there is how is it armed or activated? Are speed brakes always used in landing?  How is it used relative to also using auto-brake vs manual braking?

3 hours ago, anavsun said:

If there is how is it armed or activated?

That's a lot of questions! Arm when gear down is a good time, it should be in your landing checklist. Gear/final flaps/arm speed brake(spoiler).

It is auto activated when the gear touches down (ac dependent). If you land too smooth they might not deploy! Hence a firmish landing is the usual :D

You can deploy them manually to the detent (half way approx) in flight to slow the plane down during descent. Your pfd will often suggest it when  it messes up the vnav!

1 hour ago, sloppysmusic said:

That's a lot of questions! Arm when gear down is a good time, it should be in your landing checklist. Gear/final flaps/arm speed brake(spoiler).

It is auto activated when the gear touches down (ac dependent). If you land too smooth they might not deploy! Hence a firmish landing is the usual 😄

You can deploy them manually to the detent (half way approx) in flight to slow the plane down during descent. Your pfd will often suggest it when  it messes up the vnav!

Yup, lots of questions for lots of details. Grateful for the answers. 🙂 I learned something new. Arming the spoiler has no default key in MSFS. It needs a new keyboard key or a joystick button assignment in MSFS.

On 2/8/2025 at 8:38 AM, sloppysmusic said:

One scenario I could possibly imagine is if you are too high on your approach (hello VNAV!) and above alt restrictions for the approach (and terrain not an issue!) then capturing and following GS early would help you to descend to 'catch up' to FAF. ATC would have to authorize of course. It's safe as long as you remember to go back to ALT hold once at intercept height if still not on LOC intercept. Of course it's safer to just alter your V/S or descent angle manually to get down........

That definitely would not be a great technique as it contains a significant threat: you'd be giving up all MCP altitude protections while using a vertical mode that could very well be inaccurate - if you're capturing a glideslope signal before you're on the localizer, you're very possibly capturing an inaccurate side lobe.  Remember that a glide slope only provides meaningful guidance when you're on the localizer; you never want to use it otherwise.  This is why I say that there would never be a reason for an airplane to be configured to capture a glideslope before a localizer.  There's never a scenario in which you would want to do that.

Your scenario wouldn't give you any descent advantages over level change or VS anyway, and those modes will honor MCP altitude restrictions.

On 2/8/2025 at 8:02 AM, anavsun said:

1. Use VOR/LOC and then APP
2. Use APP and then VOR/LOC
3. Ignore VOR/LOC and just use the APP

Not only is option 2 not a valid choice as pointed out above, but if you try it you'll see you couldn't make it work if you wanted to.  Once approach mode has become active (loc and GS captured), you cannot exit approach mode by de-selecting it or selecting another mode.  In other words, pressing VOR/loc will do nothing.

Normal ways to exit approach mode are a toga press, or shutting off both FDs or detuning nav radios.