Pressing LOC before APP is not required.  I'm not sure where this old wives tale popped up (likely in sim land, or back in the days of the first autopilots), but it's just that: an old tale.

 

I quote from the PMDG 777 Tutorial 1 (pg. 91 in the PDF):

 

"It’s always a good idea to intercept the localizer before the glideslope – in fact, the configuration options of this particular PMDG 777-200LR/F airframe does not even allow for the GS to be intercepted before the LOC.". So this differs of course per livery. Why is this an option by the way, if you should or should not intercept the localizer before the glidescope? Why do some do it, some don't? Is it to get a better approach?

 

In FSX the LOC indication appears some 10 nm before the G/S indication shows up. That results in a few seconds, where people are tempted to press the LOC button (APP wouldn't work yet during those seconds).

 

 

Deniz,

the KLM livery actually defaults to "no G/S before LOC" ... and I've just noticed you fly a fictional livery!  

 

I am pretty sure I did make sure LOC was in green before I pressed APP... so I would assume it would put me on the glidescope? Anyway, I'll try it out tonight

And what's the problem with flying a fictional livery? Not correct with the real world I guess? I just wanted to fly with KLM   Although I do understand that (at least if I remember correctly) KLM flies Airbus and not Boeings across the atlantic.

 

 

I quote from the PMDG 777 Tutorial 1 (pg. 91 in the PDF):

"It’s always a good idea to intercept the localizer before the glideslope – in fact, the configuration options of this particular PMDG 777-200LR/F airframe does not even allow for the GS to be intercepted before the LOC."

 

You're confusing technique and buttonology.

 

Nowhere in that quote does it say "press LOC and then press APP."  It's telling you to be below the glideslope when you intercept the localizer.  That's it.  You can press APP when following that same method with no ill effects.

 

Why press two buttons when you can press one?

You're confusing technique and buttonology.

 

Nowhere in that quote does it say "press LOC and then press APP."  It's telling you to be below the glideslope when you intercept the localizer.  That's it.  You can press APP when following that same method with no ill effects.

 

Why press two buttons when you can press one?

 

I think this is an FS'ism because i'm fairly sure if my memory serves me correctly some of the default aircraft in FS2004 used to climb into the glideslope if you hit approach before you were about to intercept the G/S!

You're confusing technique and buttonology.

 

Nowhere in that quote does it say "press LOC and then press APP."  It's telling you to be below the glideslope when you intercept the localizer.  That's it.  You can press APP when following that same method with no ill effects.

 

Why press two buttons when you can press one?

 

The PMDG tutorial first makes you press the LOC button, and then press the APP button when you intercept the localizer. That's in the 777 tutorial, but was also in the 737 tutorial, so it being a mistake would be left out, I think.

By the way - that quote was directly below the instruction to press the LOC button - so how else is someone like me, who has not the most knowledge in this, supposed to interpret that quote, given the context?

I'm with Kyle here.

I always press the APP button only and it always capture both the LOC and the GS correctly.

I'm with Kyle here.

I always press the APP button only and it always capture both the LOC and the GS correctly.

Then why is it stated to press LOC before in the PMDG tutorials? Not saying you guys are wrong, but why are they opting for telling their users to press LOC before, instead of not?

The important thing is to be below the G/S before trying to capture it, as Kyle mentioned already. (Unless you're coincidentally happening to be flying an Airbus 32x .)

 

I may push the LOC button before the APP button when I get vectored for a looong final approach, so there's a chance of overshooting the extended centreline (centerline for Kyle ), before the G/S signal is received.

 

And I fly a completely unrealistic entirely fictitious Lufthansa livery myself, occasionally ...   :rolleyes:

Then why is it stated to press LOC before in the PMDG tutorials? Not saying you guys are wrong, but why are they opting for telling their users to press LOC before, instead of not?

 

As a better practice maybe?

 

Sometimes you are not clear for the approach  but to join the LOC only. In that case you should only pres LOC until ATC clears you for the approach.

Then why is it stated to press LOC before in the PMDG tutorials? Not saying you guys are wrong, but why are they opting for telling their users to press LOC before, instead of not?

 

I haven't looked at the tutorial in a while.  It actually says "press LOC," or does it just refer to the LOC[alizer]?  Regardless, just because it says "do this" doesn't mean that it's required.

 

 

 

(centerline for Kyle )

 

haha - I have the most messed up version of English under my belt.  I'll alternate spellings all over the place.  I'm pretty sure it's 'gray' here, but I use 'grey;' I've occasionally used 'colour' and 'favourite' here on the forum (mostly when I first joined - less so now).  My parents live in Centreville, too, so yeah...I'm just a mess.

I haven't looked at the tutorial in a while.  It actually says "press LOC," or does it just refer to the LOC[alizer]?  Regardless, just because it says "do this" doesn't mean that it's required.

 

It says in the tutorial: "Press the MCP LOC button to arm the localizer capture mode.". And I understand your comment, but then again it IS a tutorial. I definetely know the basics of ILS approach & autoland, but I think I should expect from an aircraft-specific tutorial that it should tell me accurately what I should do in the specific aircraft.

 

Anyways, I tried reproducing the scenario just now. It seemed like I actually engaged APP too late last time.

Also, I think this is because I am used to longer glidescopes with more time to intercept the localizer. From what I gather and from my own findings, I am pretty certain that KFJK is not one of those airports  ^_^

 

 

And I understand your comment, but then again it IS a tutorial. I definetely know the basics of ILS approach & autoland, but I think I should expect from an aircraft-specific tutorial that it should tell me accurately what I should do in the specific aircraft.

 

If I've said it once, I've said it a thousand times:

Aviation is not rigid.  What one person/airline/operator does, another will do differently.

 

You can't write a tutorial that's going to capture every possible way that the 777 is operated.

If I've said it once, I've said it a thousand times:

Aviation is not rigid.  What one person/airline/operator does, another will do differently.

 

You can't write a tutorial that's going to capture every possible way that the 777 is operated.

 

I guess I misunderstood you, as I thought your method was more like "this is the way everyone does it" and not "this is the way some do it". I've gathered in my FSX days that aviation is sometimes an unnecessarily complex business. Though I guess you can find that everywhere  :rolleyes:

Sometimes ATC vectors are not ideal.

And with that I mean that sometimes they give you your last descend altitude too late.

Let's use "heading 360, descend 3000ft, cleared ILS" as our clearance example.

 

When you then arm APP (which arms both LOC and GS) you might have the GS capture while you are still on that radar vector to intercept the LOC.

 

So you will be descending on the GS to BELOW those 3000ft (departing the safe altitude on that heading) while OUTSIDE the protected area of the ILS (obstacle clearance)!

 

Some companies allow you to that.

Others only allow a descend on the GS without LOC capture during dayligh + VMC conditions (so you can remain clear of obstacles visually).

And other companies dont allow it at all. (which means you need to request a lower altitude from ATC or intercept the LOC, drop the gear and other drag devices, and try to capture the GS from above, which is ugly and can require a go around if not stabilized below 1000ft (or 500ft again depending on SOPs).

 

This also explains why those options can be set in the PMDG menu (to cater for company (or your own) SOPs).

and then turned on APP at the correct altitude (according to my FMC 1500ft for landing on RWY 04L). I did reach the 1500ft at the last moment, so maybe that's the issue? (the plane did not descend quick enough; probably a FMC error on my part)

 

The FMC does not give you any info about when to press the APP switch!

Those altitudes in the FMC LEGs page are the same as the ones on your approach plate (there can be differences if therovider of the FMC database is not the same as the provider of your charts) and they just state at what altitude the GS will be at various point along the LOC.

 

One reason they are there is so you can check your airplanes altitude and milage against those depicted on the chart.

As a backup, to make sure you have not captured a false GS!

So: read 4.5nm and 1500ft from your airplane instruments. Then check the chart sais the same.

If you read 4.5nm and 2000ft from your instruments (with GS captured) where your chart sais 4.5nm and 1500ft.....then something is wrong and you should discontinue the approach!

 

The APP button CAN be pressed at any time once cleared approach by ATC.

But it is SAFER to arm only the LOC if you would otherwise end up with GC captured and a following descend below your vecored (cleared) altitude.

9 out of 10 times, ATC vectors are perfect and so that you will first intercept the LOC. So in those case it is fine to use the APP switch.

 Does anyone have an idea why this failed? Is 1500ft too low?

Not too late. But late, yes. No need to wait with APP mode that long (except for reasoned mentioned above).

[quote name="gdscei" post="2973286" timestamp="1398169946"

Another thing btw, for the 737 NGX, there was a display mode where you could see the glidescope (or just ascend/descend path), this doesn't seem to be on the 777.. Is there an alternative to this display on there?Not sure what you mean here.

 

You mean them white ghost pointers (anticipation que) on the PFD?

They should be visible.

(unless it is an option that can be turned on/off....I dont know)

 

This is very confusing though!

 

We shall get there step by step :-)

 

1)

You will see LNAV/VNAV in white in the left hand top corner above the horizon.

You will also see a magenta diamond for both lateral and vertical path deviation.

(the vertical deviation on the PFD correspond to the path deviation indication on the ND)

The diamonds on the PFD in this case show your course deviation from your programmed FMC lateral and vertical path. (they are there pretty much the whole flight).

 

2)

Dont confuse this white LNAV/VNAV indication with the (green) FMA modes!!

I am talking about that position on the PFD where you will later on see the the ILS frequency or ident and ILS inbound course! (left/top/horizon).

 

3)

The actual AP or FD mode (green) can be something else entirely (VS and HDG for example ).

Just like you can fly with the AP (and/or FD) in VS and HDG MODE while follwing the LOC and GS deviation pointers down the ILS approach,

you can also fly with the AP (and/or FD) in VS and HDG MODE while follow your LNAV and VNAV path deviation pointers.

(Normally you would use the AP/FD in LNAV and VNAV PTH mode to follow them ofcourse.)

 

So on top in green = AP/FD mode

Left above horizon, in white = mode for vertical and lateral deviation from path (LNAV/VNAV or ILS)

 

4)

and if you are seeing that white LNAV/VNAV indication on the PFD, then you should also see two ADDITIONAL white (ghost) pointers (one along the vertical and one along the lateral deviation bar on the PFD). They represent where your localizer and glideslope are.

So you can see if you are positioned well for the Loc and GS intercept!

 

5) once the LOC/GS capture, you will see that white indication change.

It does no say LNAV/VNAV anymore. Instead you should see ILS.

Meaning that the magenta diamonds are now showing ILS deviation (the white ghost pointers are now gone).