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INSTRUMENT FLIGHT RULES WORKBOOK
CHAPTER THREE
position from which a descent to landing on the intended runway can be made at a normal rate of
descent using normal maneuvers. Circling minimums are only used in conjunction with
nonprecision approaches.
Height Above Touchdown (HAT) applies to precision and nonprecision straight-in
approaches. HAT indicates the height of the DH or MDA above the highest runway elevation in
the touchdown zone. It is an altitude expressed in AGL. The touchdown zone is the first 3000
feet of the duty runway.
1. Nonprecision
2. Precision
Height Above Airport (HAA) is also an AGL altitude, but it only applies to Circling maneuver
minima. HAA indicates the height of the MDA above the published airport elevation and affords
a minimum of 300 feet of obstruction clearance.
310. APPROACH MINIMA­WEATHER MINIMUMS
Ceiling
Before the pilot of a single-piloted aircraft can accept an approach clearance (with the intention
to land), the weather at the airfield must be equal to or above the weather minimums published
for that approach. The ceiling is expressed in feet above the published airport elevation (AGL),
and is equal to or greater than the height of the associated DH or MDA. Ceiling values are
shown in parentheses.
Visibility
Visibility minimums for an approach are listed in one of three ways. The visibility value follows
the DH or MDA (i.e., 700/40 or 700­1) and is expressed as Runway Visual Range (RVR),
Runway Visibility Value (RVV), or Prevailing Visibility (PV).
For straight-in approaches the visibility values will be either RVR, RVV, or PV. For circling
approaches, the value will always be PV. It should be noted that the visibility is separated from
the DH by a slant line (/) when it is RVR, and separated by a hyphen (­) when it is an RVV or
PV value.
RVR values are written in hundreds of feet. (An RVR value of 40 = 4000 feet.) RVV and PV
values are written in fractions of statute miles (i.e., 1/2, 3/4, 1­1/2, 2).
The ceiling and visibility values shown in parenthesis are to be used in flight planning. Review
again the Radar Instrument Approach Minimums Section.
INSTRUMENT APPROACH PROCEDURES 3-9