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6 Answers

Back Course Localizer Signals

Asked by: 5254 views Airspace, FAA Regulations

I see that there are some SIDs that utilize a back course localizer for initial course guidance such as the WAGGE TWO Departure at KRNO. The localizer signal used for the WAGGE TWO is from the ILS 16R approach, yet there is no published back course approach. Do all localizers transmit a back course signal even if there is no published back course approach?


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6 Answers

  1. Nathan Parker on Apr 19, 2013

    Antennas transmit in all directions, so yes. The course may, or may not, be usable.

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  2. Sam Dawson on Apr 20, 2013

    As Nathan wrote, yes. If there are no actual back course approaches nearby I will have instrument students track a localizer back course at a non-towered airport a few times just to see the difference from a front course.

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  3. John D. Collins on Apr 20, 2013

    Tracking on the back course or the front course is the same, that is any time you are fly the front or back course is the direction of the front course, CDI sensing is normal. Anytime you are flying on either the front course or the back course in the direction opposite of the front course, CDI sensing is reversed. Flying the full ILS procedure using a standard CDI requires tracking outbound in the localizer and using reverse sensing. then the PT, then tracking inbound on the localizer uses standard CDI sensing. On a departure procedure, tracking a back course outbound from the runway would use standard sensing.

    There is a back course used in the missed approach procedure at Aspen, CO. It is located on a mountain at 11000 MSL well south of the airport and angled so the front course is oriented to 303 degrees, but since the procedure is to intercept it and fly it outbound 303 degrees, standard CDI sensing is used to fly it. It could have been setup as a front course, but then flying it outbound would have required reverse sensing and made its use more difficult.

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  4. Dan Chitty on Apr 20, 2013

    Thank you John, Sam, and Nathan for the great feedback.

    To make sure I understand, all localizer transmitters that transmit a front course signal also transmit back course signal. In other words,since the localizer is a antenna, the antenna radiates a signal in front of the antenna and behind the antenna.

    Is my understanding correct?

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  5. John D. Collins on Apr 20, 2013


    Your understanding is correct.

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  6. Earl Kessler on Apr 21, 2013


    Reno used to have a Back Course Localizer approach a few years ago that you flew into Rwy 34L. They replaced it with a second ILS directly to 34L. A little safer since it offers vertical guidance. In this case you actually had reverse sensing unless your equipment compensated or you adjusted your needle to 164 degrees inbound to 34L. In the case of the Wagge 2 departure, you are tracking outbound from RWY 16R and there is no reverse sensing since your course is the same heading as the Localizer signal for 16R.

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