INSTRUMENT DEPARTURE PROCEDURE (DP) A preplanned Instrument Flight Rule
(IFR) air traffic control departure procedure printed for pilot use in graphic and/or textual form.
DPs provide transition from the terminal to the appropriate enroute structure.
INSTRUMENT METEOROLOGICAL CONDITIONS (IMC) Weather conditions
(visibility, ceiling and cloud clearance) below the minimums for flight under Visual Fight Rules
INTERMEDIATE APPROACH SEGMENT That part of an Instrument Approach
Procedure from the first arrival at the first navigational facility or predetermined fix, to the
beginning of the final approach.
INTERSECTION A point defined by any combination of courses, radials, or bearings of two
or more NAVAIDS. An intersection may also be defined by radial and DME.
JET ROUTES A high altitude route system extending from 18,000 feet MSL to FL450,
inclusive. The routes are predicated by high altitude navigational aids.
LOW APPROACH An approach over an airport or runway following an instrument approach
or a VFR approach including the goaround maneuver where the pilot intentionally does not
make contact with the runway.
MANDATORY ALTITUDE (INSTRUMENT APPROACH) The MSL altitude vertical to a
geographic location which an aircraft must maintain during a portion of an instrument approach.
The requirement for such may be created by airspace separation criteria or airspace separation
criteria in conjunction with obstruction clearance criteria. A mandatory altitude will be depicted
as an underlined number with a line above it.
MANEUVERING AIRSPACE Airspace used at an IAF to allow an aircraft to maneuver for a
favorable alignment with the initial approach course.
MAXIMUM ALTITUDE (INSTRUMENT APPROACH) The MSL altitude vertical to a
geographic location above which an aircraft may not be flown during an instrument approach
until after passing the location. The requirement for a maximum altitude may be created by
airspace separation criteria. On the approach plate, a maximum altitude will be depicted as a
number with a line above it.
MINIMUM CROSSING ALTITUDE (MCA) The lowest altitude at certain fixes at which an
aircraft must cross when proceeding in the direction of a higher Minimum Enroute IFR Altitude.
MINIMUM DESCENT ALTITUDE (MDA) The lowest altitude, expressed in feet above
mean sea level, to which descent is authorized on final approach or during circlingtoland
maneuvering in execution of a nonprecision instrument approach.
MINIMUM ENROUTE ALTITUDE (MEA) The altitude established between navigational
aids or reporting points on airways, air routes, or advisory routes, which will meet obstruction
clearance requirements, and which will also assure acceptable navigational signal coverage.