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I always hear that GPS can be used in lieu of DME, but I would like to know the specific regulation that states this.

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  • $\begingroup$ In the U.S. it is found in the AIM 1-2-3. $\endgroup$
    – wbeard52
    Commented Oct 4, 2023 at 5:43
  • $\begingroup$ There is no specific FAA regulation that states that GPS can be used in lieu of DME. There are Advisory Circulars and TSO's that read together provide this authority. $\endgroup$
    – user22445
    Commented Oct 5, 2023 at 16:37

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For the US, this is part of AC 90-108 "Use of Suitable Area Navigation (RNAV) Systems on Conventional Routes and Procedures"

7.a: Usage of Suitable RNAV Systems. Subject to the operating requirements in this AC, operators may use a suitable RNAV system in the following ways

(1) Determine aircraft position relative to or distance from a VOR (see first note in subparagraph 7b), TACAN, NDB, compass locator (see second note in subparagraph 7b), DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or Localizer (LOC) course.
(2) Navigate to or from a VOR, TACAN, NDB, or compass locator.
(3) Hold over a VOR, TACAN, NDB, compass locator, or DME fix.
(4) Fly an arc based upon DME

Summary on the AOPA site: Use of GPS in lieu of DME/ADF.

Note GNSS in lieu of DME doesn't include approaches, like ILS/DME. In these approaches the DME may be located at any suitable place, e.g. at the mid point of the runway length, and its 50 µs response delay recalibrated to indicate 0 at the threshold of the active runway. Something the GNSS cannot handle without additional information.

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