What is the use of GS on/off in approach ref cdu page?

europa345
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What is the use of GS on/off in approach ref cdu page?

Post by europa345 » 18 Jan 2015, 19:50

What is the use of GS on/off in approach ref cdu page?
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herculespilot
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Re: What is the use of GS on/off in approach ref cdu page?

Post by herculespilot » 18 Jan 2015, 20:40

As far as i know , you are able to disengage the G/S, to use only the localizer indication.

Maybe in case of an unreliable G/S indication.

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Re: What is the use of GS on/off in approach ref cdu page?

Post by willow » 19 Jan 2015, 03:20

I believe Thomas is correct.

If you loose the ILS receiver or do not want to use the receiver during an approach you select OFF. WilloW
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Re: What is the use of GS on/off in approach ref cdu page?

Post by bagarie » 21 Jan 2015, 20:48

To be more exaustive,

that option is used when you use the Lateral Guidance of ILS (LOC) but not the Vertical one. It's the case when you fly a LOC approach with G/S unserviceable. In this case you deselect the G/S on CDU and you can use the IAN capability: so you will follow the LOC lateral guidance of ILS and the G/P guidance using the FMC informations from the Database.

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Re: What is the use of GS on/off in approach ref cdu page?

Post by willow » 21 Jan 2015, 23:24

Excellent explanation Arnaldo - thanks, WilloW

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Re: What is the use of GS on/off in approach ref cdu page?

Post by herculespilot » 22 Jan 2015, 02:19

Wow... thats great explained indeed. And i learned hiw to improve the IAN functionality.

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Thomas Scheelen

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Re: What is the use of GS on/off in approach ref cdu page?

Post by europa345 » 22 Jan 2015, 09:20

hi

the problem is that is a litle confusing because the G/S does not disappear fron the PFD, it goes down, so you dont know if its down because you are high or because the GS is Off.
If that is how it Works in the real plane, i think is dangerous because is easy to make a mistake

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Re: What is the use of GS on/off in approach ref cdu page?

Post by vdbroeck.net » 22 Jan 2015, 10:14

In the good old days we were flying this with v/s reading the altitude/distance table on the chart. (No IAN)
Do not forget to set the new minima's for the approach. (LOC (GS OUT)) and check the new RVR

Roel

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Re: What is the use of GS on/off in approach ref cdu page?

Post by bagarie » 22 Jan 2015, 11:08

Hi Miguel,

the Glide slope Pointer (for the ILS or the Glide Path Pointer (for IAN) are in view when the signal is received.
For example if you tune an ILS frequency and the Glide Slope is out of order (sometimes happen), the PFD DON'T show any Pointer.

On Aircraft equipped with IAN, you can deselect the G|S indications to display the Glide Path indication as described above on my post.

But first of all the Crew knows when on ILS approach eventually the Glide Slope is out of order: first is aknoledged by a NOTAM and also the ATC or the ATIS inform you of the type of the approach.
So you know exactly what will you expect on the approach.

Hi Roel,

also aircraft not equipped with IAN, can make all NON precision approach with LNAV/VNAV.

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Arnaldo

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Re: What is the use of GS on/off in approach ref cdu page?

Post by herculespilot » 22 Jan 2015, 12:30

Yes, but what he want to know is, whether the G/S pointer is still indicated after disengaging. For a faulty G/S the pointer might indicate something strange, If you aware of this, its no issue.

But i wondering too, if the pointer is still visible, even with selecting G/S off in the FMC. I can't imagine that.

i guess.
G/S offv = No G/S pointer

If you fly an IAN Approach, the IAN G/P pointer appears. It should be the only pointer for vertical guidance i guess.

What wrote bill buffer about it, in his FMC guide?


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Thomas Scheelen

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