K asked in Cars & TransportationAircraft · 1 decade ago

What are alternate IFR limits?

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  • 1 decade ago
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    FAR 91.169 states for aircraft other than helicopters, ...

    (2) Except as provided in paragraph (b) of this section, an alternate airport.

    (b) Paragraph (a)(2) of this section does not apply if :

    (1) Part 97 of this chapter prescribes a standard instrument approach procedure to, or a special instrument approach procedure has been issued by the Administrator to the operator for, the first airport of intended landing; and

    (2) Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:

    (i) For aircraft other than helicopters. For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles.

    (ii) For helicopters. At the estimated time of arrival and for 1 hour after the estimated time of arrival, the ceiling will be at least 1,000 feet above the airport elevation, or at least 400 feet above the lowest applicable approach minima, whichever is higher, and the visibility will be at least 2 statute miles.

    (c) IFR alternate airport weather minima. Unless otherwise authorized by the Administrator, no person may include an alternate airport in an IFR flight plan unless appropriate weather reports or weather forecasts, or a combination of them, indicate that, at the estimated time of arrival at the alternate airport, the ceiling and visibility at that airport will be at or above the following weather minima:

    (1) If an instrument approach procedure has been published in part 97 of this chapter, or a special instrument approach procedure has been issued by the Administrator to the operator, for that airport, the following minima:

    (i) For aircraft other than helicopters: The alternate airport minima specified in that procedure, or if none are specified the following standard approach minima:

    (A) For a precision approach procedure. Ceiling 600 feet and visibility 2 statute miles.

    (B) For a nonprecision approach procedure. Ceiling 800 feet and visibility 2 statute miles.

    (ii) For helicopters: Ceiling 200 feet above the minimum for the approach to be flown, and visibility at least 1 statute mile but never less than the minimum visibility for the approach to be flown, and

    (2) If no instrument approach procedure has been published in part 97 of this chapter and no special instrument approach procedure has been issued by the Administrator to the operator, for the alternate airport, the ceiling and visibility minima are those allowing descent from the MEA, approach, and landing under basic VFR.

    (d) Cancellation. When a flight plan has been activated, the pilot in command, upon canceling or completing the flight under the flight plan, shall notify an FAA Flight Service Station or ATC facility.

    So, follow the 1-2-3 rule: 1 hour before and 1 hour after estimated time of arrival, the celing needs to be at least 2000 feel with 3 statute miles visibility.

    Source(s): commercial pilot, advanced ground instructor, CFI-candidate http://www.airweb.faa.gov/Regulatory_and_Guidance_...
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  • 1 decade ago

    Perfect answer by Barry...a soon to be CFI! Bravo.

    We just use the 1-2-3 rule ~ see above response to figure out the details.

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