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saifm

How to extend the localizer?

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This is not a feature exclusive only to the Boeing 777, I believe. It is all about the FMC, and i want to know how to extend the localizer from the FMC to allow an earlier localizer capture!


Saif Salama

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It's a relatively simple procedure...common to all modern Boeing Aircraft.  It is normally used when on ATC radar vectors & also helps maintain situational awareness & keeps the ND 'tidy' thus reducing clutter.

 

You are actually creating an 'extended centreline' to the runway in question by using the DIRECT INTERCEPT (DIR INTC) technique to either the actual RWY entry in the LEGs Page, or alternatively an approach FIX  in the LEGs Page that is positioned along the runway centreline.  The transmitting range of the Localiser Transmitter is finite.

 

The Boeing terminology is Intercepting a Leg (Course) to a Waypoint

 

See the PMDG NGX FCOMv1 SP.11.5 (pp235) for the official guidance.

 

When creating an 'extended centreline' it is best to select lower modes of PITCH  (FLCH, V/S or ALT HOLD) & ROLL (HDG SEL) automation.  These lower levels or modes of automation are sometimes referred to as 'Tactical Modes'. 

 

You must always remember that any modifications to the LEGS page will undoubtedly alter the VNAV PTH - & this can complicate the issue as the track miles to the RWY or WPT will reduce dramatically in most cases. 

 

Use a lower level of automation!

 

Established downwind with a 'busy' ND prior to any LEGS Page modifications:

 

DIR%20INTC%201.jpg

 

Approach WPT copied into SCRATCHPAD:

 

DIR%20INTC%202.jpg


Steve Bell

 

"Wise men talk because they have something to say.  Fools talk because they have to say something." - Plato (latterly attributed to Saul Bellow)

 

The most useful tool on the AVSIM Fora ... 'Mark forum as read'

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Don't forget that when you perform the DIR INTC you must enter an Inbound Course (INB CRS) at LSK 6R BEFORE you EXEC any changes.

 

INBD CRS entered into SCRATCHPAD:

 

DIR%20INTC%203.jpg

 

INBD CRS copied to LSK 6R:

 

DIR%20INTC%204.jpg

 

EXEC button pressed:

 

DIR%20INTC%205.jpg

 

Finally....

 

In theory you could intercept this extended centreline using LNAV well beyond the range of the associated ground based Localiser Transmitter (IRL ranges vary):

 

DIR%20INTC%207.jpg

 

Using HDG SEL & ALT HOLD to intercept the ILS these are lower modes/levels of automation than say LNAV & VNAV.

 

Note that VNAV is still displaying PTH info on the right side of the ND because the APP WPT we selected had an associated ALT entry on the LEGs Page:

 

DIR%20INTC%206.jpg


Steve Bell

 

"Wise men talk because they have something to say.  Fools talk because they have to say something." - Plato (latterly attributed to Saul Bellow)

 

The most useful tool on the AVSIM Fora ... 'Mark forum as read'

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Don't forget that when you perform the DIR INTC you must enter an Inbound Course (INB CRS) at LSK 6R BEFORE you EXEC any changes.

 

INBD CRS entered into SCRATCHPAD:

 

DIR%20INTC%203.jpg

 

INBD CRS copied to LSK 6R:

 

DIR%20INTC%204.jpg

 

EXEC button pressed:

 

DIR%20INTC%205.jpg

 

Finally....

 

In theory you could intercept this extended centreline using LNAV well beyond the range of the associated ground based Localiser Transmitter (IRL ranges vary):

 

DIR%20INTC%207.jpg

 

Using HDG SEL & ALT HOLD to intercept the ILS these are lower modes/levels of automation than say LNAV & VNAV.

 

Note that VNAV is still displaying PTH info on the right side of the ND because the APP WPT we selected had an associated ALT entry on the LEGs Page:

 

DIR%20INTC%206.jpg

 

I LOVE YOU!!

THIS IS EVEN EXPLAINED BETTER THAN MY MATHS TEACHER

THANK YOU SO MUC


Saif Salama

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Happy to have helped.


Steve Bell

 

"Wise men talk because they have something to say.  Fools talk because they have to say something." - Plato (latterly attributed to Saul Bellow)

 

The most useful tool on the AVSIM Fora ... 'Mark forum as read'

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Depending on the sim software obviously, but in the aircraft, when you are close to the destination ILS (the ILS shows up < 250nm to go) you can select the inbound course with the following.

 

Dep/Arr page

LSK6R will give you the inbound intercept course to the final approach fix for the ILS.

 

eg (something like):

 

INTCPT ILL40 <--

 

It's a bit quicker than the above but, as stated, I'm not sure what mod state the simulator FMC is.


GregL :-)

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A picture paints a thousand words (and avoids ambiguity as has been seen on another thread!!!!)

 

So: Here you go, from the Fcom.

 

the final intercept course is the LSK6R, it WILL drop all waypoints from your current position to that waypoint and give you an automatic extended centreline. Use it when in HDG SEL. Enjoy. Achieved with a single button press and execute.


GregL :-)

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A picture paints a thousand words (and avoids ambiguity as has been seen on another thread!!!!)

 

So: Here you go, from the Fcom.

 

the final intercept course is the LSK6R, it WILL drop all waypoints from your current position to that waypoint and give you an automatic extended centreline. Use it when in HDG SEL. Enjoy. Achieved with a single button press and execute.

 

 

YES,  you are certainly right, it is really faster!! 

thank you


Saif Salama

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The above information on intercepting waypoints on specific headings is invaluable!

 

Often, especially in the Caribbean, you will be asked to intercept beacons on specific radials and the way given by G-CIVA is excellent. Either that or you can drop the beacon into the FIX page and project a radial out and fly that, just don't forget to fly it in TRK and the computer will handle the drift for you!

 

Happy landings.


GregL :-)

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Steve and Greg, thanks for your valuable input, much appreaciated by myself and others no doubt. I'll be looking forward to trying the above when she's released :)


Alaister Kay

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