Re: how does the ILS really work on the B757/767

Date:         06 Apr 99 11:46:14 
From:         jrp59@gte.net (Ron Parsons)
Organization: gte.net
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In article <airliners.1999.336@ohare.Chicago.COM>, "Paul MacDougall" <pmpub@simcoe.igs.net> wrote:
>just wondering if anyone is familiar with the inner workings of the ILS
>system and how it integrates with the FMC....ie if you dial in the correct
>localizer frequency but mis-set the front course setting how does the system
>work or not work... does it matter if you mis-set it only 10 degrees verses
>80 degrees....my AOM is not very helpful and I know this system has screwed
>a few people...

The FMC will complain if you tune the wrong frequency for the selected
runway, but doesn't check the course set in.

There are a number of aeronautical myths about what will happen with
various amounts of misset course but no hard data that I know of.

Once on the Loc, the FMC does drop the DME/DME or VOR/DME updating and
uses the LOC.

Some of the myths and scares you might hear date from very early versions
of FMC software and may or may not have any value on any particular
version.

Ron