Anonymous asked in Cars & TransportationAircraft · 1 decade ago

are they any requirements for how far aways an alternate airport must be under commercial and IFR?

I mean, imagine you are flying Boston-Dallas. In Dallas, the weather is that bad that you have to fly to an alternate. First, before you take-off at Boston, do you already know which alternate that would be (or do you check just when at Dallas for other airports)? And second, what are the requirements for calculating the alternate (I mean, must he be like at least 100 n.m. away, must he be at least 1 hour away, or how do you make it)?

5 Answers

  • Favorite Answer

    When filing the IFR flight plan you must list your alternate. So you plan your alternate based on FORCASTED weather or availability of a Instrument approach and fuel requirements.

    Distance is only a factor if fuel is an issue.

    § 91.169 IFR flight plan: Information required.


    (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.

  • 4 years ago

    Ifr Alternate Requirements

  • 1 decade ago

    In the U.S., the requirements are not identical for all operators, but they are similar. Obviously, the alternate must be within reach of the fuel load onboard the aircraft, just like the destination airport.

    For Part 91 operators, the alternate airport must have a monitored navaid and weather reporting capabilities, and must not have only GPS-based approach procedures (there are some exceptions). The forecast weather for the alternate must meet alternate minimums.

    For Part 121 operators, such as airlines, it's more complicated, and the individual requirements may be determined by OpsSpecs approved for each airline. For aircraft with more than two engines and with one engine out and in still air, the alternate must be within three hours' flying time; for twins, the alternate must be within one hour's flying time with one engine out. Part 121 also has different requirements for when an alternate must be filed in the flight plan.

    The alternate is normally selected in advance and filed as part of the flight plan. However, it is not mandatory that it be used as an alternate once the flight has begun if an alternate is required; it just has to be available.

    Source(s): Memory, Federal Air Regulations (a great many FARs mention alternate airports), FAA publications
  • Rob G
    Lv 6
    1 decade ago

    The above answers are good, but I wanted to add that there is no minimum distance that the alternate must be away from your destination. It's mostly all about the weather conditions. In fact, many times airline dispatchers will file a "paper alternate". This means they will file an alternate that is sometimes very close to the destination, just to be legal. Why? Because they and the pilots know that they will be able to get into their destination but legally they must file an alternate. They file one very close if weight and fuel is a factor. It's not a practice I recommend that a private pilot do. I've done flights in the airlines where my alternate was only about 10 miles away.

    Source(s): former airline pilot
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  • 1 decade ago

    To Answer your Questions in order:

    -No, It's governed by fuel. See explanation below.

    -Yes, that would be on your flight plan generated by the company ops center computer. The alternate airport must be suitable for your type of airplane and most companies use online airports where their own handling is available.

    -forecast weather for the expected period of arrival must be above the minimums specified in the previous answers and you must have enough fuel to fly to your destination, fly an approach, go around, proceed to your alternate and still have 45 minutes at normal cruising speed in the tanks. Exception for part 91 is destination 2000' and three and similiar exceptions may exist for part 135 and part 121(commercial) operators as defined in their ops specs for no-alternate IFR.

    For your scenario, the filed alternate can be as close as Love Field or as far as Tampa or farther. It all depends on forecasts and available fuel.

    Source(s): FAR 91.167 Personal experience
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