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3 Answers

GPS in place of VOR

Asked by: 1838 views FAA Regulations, Instrument Rating

I have a certified IFR GPS with WAAS and Dual VOR's. With the certified WAAS navigator do I still need to do 30 day VOR checks?

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3 Answers



  1. Russ Roslewski on Mar 31, 2022

    The first sentence of 91.171 a says “No person may operate a civil aircraft under IFR using the VOR system of radio navigation unless…”

    If you do not intend to use VORs to navigate, there is no requirement to do the checks. With a WAAS GPS you are not required to have any VOR capability to fly IFR.

    However, it’s still a good idea to do the checks, as GPS outages do happen (had one happen to me about a month ago, it affected about a 50 nm diameter area).

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  2. Mark Kolber on Mar 31, 2022

    The only place I disagree a tiny bit with you Russ is you “if you do not intend to use” statement. that 91.171 says

    “No person may operate a civil aircraft under IFR using the VOR system of radio navigation unless…”

    not

    “No person may intend to operate a civil aircraft under IFR using the VOR system of radio navigation unless.

    Unanticipated outages aside, I’m thinking of a situation in which the pilot instructed by ATC to intercept or cross a radial in circumstances where (a) the pilot doesn’t know how to duplicate it with your GPS or (b) it’s simply more efficient to tune in and follow a VOR CDI or bearing pointer. (How many examples of both (a) and (b) do you and I see regularly?)

    I’m trying to picture the success of a defense to a pilot deviation due to an out-of-tolerance VOR receiver consisting of, “well, I know I have the equipment but I didn’t plan to use it…”

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  3. Russ Roslewski on Mar 31, 2022

    I was thinking more of the “preflight considerations” scenario, where the pilot has no intention of using VORs for the flight, and therefore doesn’t need a 30-day VOR check. If you INTEND to use VORs on the flight, then yes, you need the check (lack of the word “intent” in the regulations notwithstanding).

    But say you don’t intend to use VORs, and don’t do the 30-day check. If you get in the air and there’s a GPS outage, well then if you’re not allowed to use VOR because you didn’t do the 30-day check, then you have no suitable navigation system, and therefore have an emergency. Which, of course, means you then CAN use VORs, under emergency authority.

    I do agree that if you haven’t done the 30-day check, you can’t use VORs just because they’re more convenient for some unexpected ATC clearance. You have to use GPS to navigate that radial.

    But the (unsuccessful) defense for your deviation scenario would more completely be “I didn’t intend to use VORs, so I hadn’t done the check, AND I don’t know how to use my GPS equipment to do it either.”

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