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SESK: Stuff Everyone Should Know · sesk.info/ifr-moca-22nm

Using VOR navigation, within how far of the VOR may you fly below the MEA down to the MOCA?

Within 22 nautical miles of that VOR.

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  1. 12 nautical miles
  2. 30 nautical miles
  3. 22 nautical miles ✔

Why: 91.177 lets you descend below the MEA but not below the MOCA while you have navigation signals. For VOR navigation, this applies only within 22 nautical miles of the VOR.

Huh, didn't know that: MOCA meets obstacle clearance requirements for the whole route segment, but assures good navigation signals only within 22 nautical miles of a VOR.

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An airplane yells at his rebellious son: 'Watch that altitude, young man!'
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References

Answer: 22 nautical miles. 91.177 lets you descend below the MEA but not below the MOCA while you have navigation signals. For VOR navigation, this applies only within 22 nautical miles of the VOR.

  1. 14 CFR 91.177 Minimum altitudes for IFR operations www.law.cornell.edu/cfr/text/14/91.177
    this applies only when the aircraft is within 22 nautical miles of that VOR
    Checked 2026-10-10.
  2. Pilot/Controller Glossary: MOCA www.faa.gov/air_traffic/publications/atpubs/pcg_html/glossary-m.html
    assures acceptable navigational signal coverage only within 25 statute (22 nautical) miles of a VOR
    Checked 2026-10-10.

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