91.423 Minimum altitudes for IFR flights

• Except when necessary for take-off or landing, a pilot-in-command must not operate an aircraft under IFR below--
  • (1) the applicable minimum altitudes published in the applicable AIP; or
  • (2) if an applicable minimum altitude is not published in the applicable AIP--
    • (i) for operations over a mountainous zone designated under Part 71 or applicable AIP, a height of 2000 feet above the highest obstacle within a horizontal radius of 5 nm from the position of the aircraft; or
    • (ii) a height of 1000 feet above the highest obstacle within a horizontal radius of 5 nm from the position of the aircraft.