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Substituting MAP timing with GPS

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FAA Regulations, Instrument Rating, Student Pilot

Assume you’re performing a non precision approach where the MAP is defined by timing from the FAF to the MAP.

Is substituting this timing with a certified IFR GPS legal? Assume you have loaded the approach and the GPS has automatically added the MAP (RWxx) into the flightplan. You are not using the GPS to navigate to this waypoint (still using the loc/vor to laterally get there) only to identify it.

Is there FAA docs (AIM/FAR/Handbook/ACs) that support this one way or the other.

 

One example is the ILS OR LOC 05 at KHUF. If flying the LOC, the only way you can identify the MAP is via timing.

1 Answers

  1. Best Answer


    John D Collins on Jan 23, 2020

    Yes, you may identify the MAP using the GPS. Uses of Suitable RNAV Systems is discussed in AC 90-108A in section 7 and in AIM Section 1-2-3 (c.) Uses of Suitable RNAV. The specific clause in the AIM is:

    c. Uses of Suitable RNAV Systems. Subject to the operating requirements, operators may use a suitable RNAV system in the following ways.
    1. Determine aircraft position relative to, or distance from a VOR (see NOTE 6 below), TACAN, NDB, compass locator, DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course.

    The approach chart locates the MAP at 049 degrees 4.7 NM from the FAF on the top of the timing chart and in the profile and airport diagrams. It is also he runway threshold. In this instance, one could use either a distance of 4.7 NM from YINNO or the RW05 waypoint in the database. The final approach lateral course is defined by the localizer and it must be used for lateral guidance on the final approach segment.

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