Instrument Flight Rules


  • Instrument flight rules govern a specific type of aviation where flight may be conducted with reference to the flight instruments alone (i.e., no outside references)

Logging IFR Time:

  • A person may log instrument time only for that flight time when the person operates the aircraft solely by reference to instruments under actual or simulated instrument flight conditions
    • Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions
    • This is broken apart in most logbooks to differentiate between actual and simulated time
  • An authorized instructor may log instrument time when conducting instrument flight instruction in actual instrument flight conditions
  • For the purposes of logging instrument time to meet the recent instrument experience requirements of FAR 61.57(c) of this part, the following information must be recorded in the person's logbook:
    • The location and type of each instrument approach accomplished; and
    • The name of the safety pilot, if required
  • A person can use time in a flight simulator, flight training device, or aviation training device for acquiring instrument aeronautical experience for a pilot certificate, rating, or instrument recency experience, provided an authorized instructor is present to observe that time and signs the person's logbook or training record to verify the time and the content of the training session

IFR Operations to High Altitude Destinations:

  • Pilots planning IFR flights to airports located in mountainous terrain are cautioned to consider the necessity for an alternate airport even when the forecast weather conditions would technically relieve them from the requirement to file one
  • The FAA has identified three possible situations where the failure to plan for an alternate airport when flying IFR to such a destination airport could result in a critical situation if the weather is less than forecast and sufficient fuel is not available to proceed to a suitable airport
    • An IFR flight to an airport where the Minimum Descent Altitudes (MDAs) or landing visibility minimums for all instrument approaches are higher than the forecast weather minimums specified in 14 CFR Section 91.167(b). For example, there are 3 high altitude airports in the U.S. with approved instrument approach procedures where all of the MDAs are greater than 2,000 feet and/or the landing visibility minimums are greater than 3 miles (Bishop, California; South Lake Tahoe, California; and Aspen-Pitkin Co./Sardy Field, Colorado). In the case of these airports, it is possible for a pilot to elect, on the basis of forecasts, not to carry sufficient fuel to get to an alternate when the ceiling and/or visibility is actually lower than that necessary to complete the approach
    • A small number of other airports in mountainous terrain have MDAs which are slightly (100 to 300 feet) below 2,000 feet AGL. In situations where there is an option as to whether to plan for an alternate, pilots should bear in mind that just a slight worsening of the weather conditions from those forecast could place the airport below the published IFR landing minimums
    • An IFR flight to an airport which requires special equipment; i.e., DME, glide slope, etc., in order to make the available approaches to the lowest minimums. Pilots should be aware that all other minimums on the approach charts may require weather conditions better than those specified in 14 CFR Section 91.167(b). An inflight equipment malfunction could result in the inability to comply with the published approach procedures or, again, in the position of having the airport below the published IFR landing minimums for all remaining instrument approach alternatives

Requirements to operate IFR:

  • Filed an IFR flight plan
  • Received an appropriate ATC clearance
  • IFR rated/licensed
  • IFR equipped aircraft

Fuel requirements for flight in IFR conditions:

  • No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to:
    • Complete the flight to the first airport of intended landing;
    • *Fly from that airport to the alternate airport; and
    • Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed
  • *Fuel to fly from the intended airport to the alternate airport is not required if:
    • Part 97 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
    • Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:
      • 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' above the airport elevation and the visibility will be at least 3 statute miles
      • 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' above the lowest applicable approach minima, whichever is higher, and the visibility will be at least 2 statute miles


  • When weather conditions permit, during the time an IFR flight is operating, it is the direct responsibility of the pilot to avoid other aircraft since VFR flights may be operating in the same area without the knowledge of ATC
    • Traffic clearances provide standard separation only between IFR flights