(a) Operation of aircraft at minimum altitudes. Except when
necessary for takeoff or landing, no person may operate an aircraft under
IFR below --
(1) The applicable minimum altitudes prescribed in parts 95 and 97 of
this chapter; or
(2) If no applicable minimum altitude is prescribed in those parts --
(i) In the case of operations over an area designated as a mountainous
area in part 95, an altitude of 2,000 feet above the highest obstacle
within a horizontal distance of 4 nautical miles from the course to be
(ii) In any other case, an altitude of 1,000 feet above the highest
obstacle within a horizontal distance of 4 nautical miles from the course
to be flown.
However, if both a MEA and a MOCA are prescribed for a particular route
or route segment, a person may operate an aircraft below the MEA down to,
but not below, the MOCA, when within 22 nautical miles of the VOR
concerned (based on the pilot's reasonable estimate of that distance).
(b) Climb. Climb to a higher minimum IFR altitude shall begin
immediately after passing the point beyond which that minimum altitude
applies, except that when ground obstructions intervene, the point beyond
which that higher minimum altitude applies shall be crossed at or above
the applicable MCA.