"Mark Hansen" wrote in message
...

During my instrument training, I learned that I would have "normal"
CDI sensing whether flying in the localizer front course or out the
back course.

However, At our local International airport (Sacramento, CA), one
of the runways (16R/34L) has an ILS on both 16R and 34L, although
the ILS for 34L is currently out of service.

While flying the ILS approach to runway 16R, I was to continue
straight out after a touch and go, so I planned to follow the
localizer. The D.E. with me said that I would have reverse sensing
while flying out the back course.

What!?! That's not what I learned. While flying out, I noticed that
the needle displaced further while he was 'correcting' in what I
felt was the wrong direction. This seemed to make my point, but
he then said that I was getting 'correct' sensing due to the fact
that that particular runway has an ILS on both ends, both on the
same frequency.

OK, this gave me pause - I had never noticed that before. In looking
at the ILS 16R and ILS 34L approach charts, they both are on frequency
111.1 - although they have different Identifier codes.

How does this work? I thought the Localizer antennas operated in both
directions, ahead of the antenna and behind as well. When they both
use the same frequency, are they omni-directional?

Assuming they are omni-directional, does that mean you will receive
both signals while overflying the runway?

Given that the ILS for 34L was out of service, there is no doubt
that I should get normal sensing while flying out the back course,
however both my CFII and the Designated Examiner had this reversed.

How can a lowly student be correct and his CFII and Designated Examiner
be wrong?


Where ILSs are installed at both ends of a runway and operate on the same
frequency they do not operate simultaneously. The switching used ensures
that only one can be selected at a time.