INSTRUMENT FLIGHT RULES WORKBOOK
308. APPROACH MINIMA
Approach minimums can be found in the fifteen volumes of Low Altitude Instrument Approach
Procedures. There are several terms that must be understood when discussing approach minima.
The first is Decision Height or DH.
Decision Height is that altitude at which a decision must be made, during an ILS or PAR
instrument approach, to either continue the approach or to execute a missed approach. A missed
approach must be initiated if visual reference to continue the approach has not been established.
The required visual reference means that section of the visual aids (lights) or of the approach
area which should have been in view for sufficient time for the pilot to make an assessment of
the aircraft position and rate of change of position, in relation to the desired flight path.
The DH is specified in MSL and only applies to precision approaches (e.g., PAR and ILS). Turn
to the Radar Instrument Approach Minimums section of your Vol. 15 Flight Information
Publication (Terminal). Radar approach minimums will be found in the black-bordered pages.
Notice the DH\MDAVIS section.
Minimum Descent Altitude (MDA) is the lowest altitude, expressed in feet above mean sea
level (MSL), to which descent is authorized on final approach or during circle-to-land
maneuvering in execution of a standard instrument approach procedure where no electronic
glideslope is provided.
*1. MDA applies to _______________ approaches.
*2. DH applies to _______________ approaches.
(Answers on next page)
309. APPROACHES TYPES OF LANDINGS
A pilot executing precision or nonprecision approaches will make either a straight-in landing or a
circling maneuver to land on the duty runway. For example, if a pilot received a clearance for a
VOR RWY 19 approach at NAS Pensacola, he would use a straight-in landing procedure if the
duty runway at NAS Pensacola was 19. However, if the duty runway was 7R, the pilot would
make the approach to RWY 19 and upon sighting the duty runway, circle (or, in other words,
maneuver) to land on RWY 7R.
Straight-in Minimums are shown on the approach plate when the final approach course is
within 30º of the runway alignment and a normal descent can be made from the IFR altitude
shown on the approach plate to the runway surface. When either the normal rate of descent or
the runway alignment factor of 30º is exceeded, a circling procedure must be used.
Circling Minimums provide obstacle clearance when pilots remain within the appropriate area
of protection. Pilots should remain at or above the circling altitude until the aircraft is in a
3-8 INSTRUMENT APPROACH PROCEDURES