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6 Answers

After going through AIM1-2-3 and AC90-108 on monitoring NAVAID.

Asked by: 3320 views Commercial Pilot, FAA Regulations, General Aviation, Instrument Rating

So, after going through the AIM and AC90-108, I found out two interesting facts as to whether or not monitor underlying NAVAID(such as localizer, VOR, etc...) when flying final approach segment.

According to the AIM1-2-3, under the NOTE, it states that "use of a suitable RNAV system as an Alternate Means of Navigation when a VOR, DME, VORTAC, VOR/DME, TACAN, NDB, or compass locator facility including locator outer marker and locator middle marker is operational and the respective aircraft is equipped with operational navigation equipment that is compatible with conventional navaids. For example, if equipped with a suitable RNAV system, a pilot may fly a procedure or route based on operational VOR using that RNAV system without monitoring the VOR."

So, does procedure include the final segment as well?

Secondly the text from the note states that "  Pilots may not substitute for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final
approach segment. This restriction does not refer to instrument approach procedures with “or GPS” in the title when using GPS or WAAS. These allowances do not apply
to procedures that are identified as not authorized (NA) without exception by a NOTAM, as other conditions may still exist and result in a procedure not being available. For example, these allowances do not apply to a procedure associated with an expired or unsatisfactory flight inspection, or is based upon a recently decommissioned NAVAID." which is bit difficult to understand, but still sounds relevant to the issue I am having trouble with.

This text is also mentioned on AC90-108.

From AC-108, under "8. USES OF SUITABLE RNAV SYSTEMS NOT ALLOWED BY THIS AC" it lists the circumstances when suitable RNAV cannot be used in place of primary means of navigation such as VOR, NDB, LOC...

a. NOTAMed Procedures. Unless otherwise specified, navigation on procedures that are identified as not authorized (“NA”) without exception by a NOTAM. For example, an operator may not use a RNAV system to navigate on a procedure affected by an expired or unsatisfactory flight inspection, or a procedure that is based upon a recently decommissioned NAVAID.

b. Substitution on a Final Approach Segment (FAS). Substitution for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the FAS. 

c. Lateral Navigation on LOC-Based Courses. Lateral navigation on LOC-based courses (including LOC back-course guidance) without reference to raw LOC data.

So, I can deduce from the above texts that I cannot fly the final approach segment with RNAV for VOR, NDB, LOC, etc... but for LOC, I need to have reference to raw LOC data, which means just dialing in localizer frequency but fly with RNAV?(I do not get what they meant by "with reference to raw LOC data.)

Connor.

 

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6 Answers

  1. Best Answer


    Joshua Clark on Nov 29, 2016

    Connor,
    You would still need to fly the localizer course using the localizer data and not the GPS data.

    The AIM did change in May allowing for the use of the GPS on the final approach segment except for localizer courses.
    “5. Use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure based on a VOR, TACAN or NDB signal, is allowable. The underlying NAVAID must be operational and the NAVAID monitored for final segment course alignment.”

    The AC has not been revised since the AIM revision, so it will not reflect that change yet.

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  2. connor on Nov 29, 2016

    Thank you Joshua,

    I hope New AC comes out very soon to apply changes.
    I wonder why AIM came with revised NOTES but not the AC…

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  3. John D Collins on Nov 30, 2016

    The AIM guidance update is a clarification, not really a change.

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  4. Mark Kolber on Nov 30, 2016

    Whether “clarification” or “change” is a matter of perspective. Either way, it has given the FAA’s
    “blessing” to something pilots have been doing anyway.

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  5. John D Collins on Nov 30, 2016

    Mark,

    True. But in effect it means that the VOR/NDB must be operating and displayed and still is primary. The part 121/135 Ops spec does not require the VOR/NDB to be operating or monitored.

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  6. Dan Chitty on Dec 02, 2016

    John

    Why did the FAA exclude parts 135/121 ?

    Regards

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