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SESK: Stuff Everyone Should Know · sesk.info/ifr-class-a-clearance

To operate in Class A airspace, you must be on which kind of flight plan and clearance?

IFR, with a clearance received before entry.

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  1. IFR, with an ATC clearance received before entering ✔
  2. VFR with flight following
  3. IFR only, no clearance needed

Why: Class A airspace runs from 18,000 feet MSL up to and including FL600, and 91.135 says operations may be conducted only under an ATC clearance received prior to entering. The AIM says all persons must operate under IFR.

Huh, didn't know that: Class A also requires an operable two-way radio and the transponder and ADS-B equipment listed in the rule.

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References

Answer: IFR, with an ATC clearance received before entering. Class A airspace runs from 18,000 feet MSL up to and including FL600, and 91.135 says operations may be conducted only under an ATC clearance received prior to entering. The AIM says all persons must operate under IFR.

  1. 14 CFR 91.135 Operations in Class A airspace www.law.cornell.edu/cfr/text/14/91.135
    Operations may be conducted only under an ATC clearance received prior to entering the airspace.
    Checked 2026-10-10.
  2. AIM 3-2 Controlled Airspace www.faa.gov/air_traffic/publications/atpubs/aim_html/chap3_section_2.html
    Unless otherwise authorized, all persons must operate their aircraft under IFR.
    Checked 2026-10-10.

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