Aeronautical Information Manual (AIM), page 391

Index   390 -- Page 391 -- 392

e. Published Approach Minimums. Approach

minimums are published for different aircraft
categories and consist of a minimum altitude (DA,

DH, MDA) and required visibility. These minimums

are determined by applying the appropriate TERPS

criteria. When a fix is incorporated in a nonprecision

final segment, two sets of minimums may be

published: one for the pilot that is able to identify the

fix, and a second for the pilot that cannot. Two sets of

minimums may also be published when a second

altimeter source is used in the procedure. When a

nonprecision procedure incorporates both a

stepdown fix in the final segment and a second
altimeter source, two sets of minimums are published
to account for the stepdown fix and a note addresses
minimums for the second altimeter source.

f. Circling Minimums. In some busy terminal
areas, ATC may not allow circling and circling
minimums will not be published. Published 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 continuously in a position from
which a descent to a landing on the intended runway
can be made at a normal rate of descent using normal
maneuvers. Circling may require maneuvers at low
altitude, at low airspeed, and in marginal weather
conditions. Pilots must use sound judgment, have an
indepth knowledge of their capabilities, and fully
understand the aircraft performance to determine the
exact circling maneuver since weather, unique airport
design, and the aircraft position, altitude, and
airspeed must all be considered. The following basic
rules apply:

1. Maneuver the shortest path to the base or

downwind leg, as appropriate, considering existing

weather conditions. There is no restriction from

passing over the airport or other runways.

2. It should be recognized that circling
maneuvers may be made while VFR or other flying
is in progress at the airport. Standard left turns or
specific instruction from the controller for
maneuvering must be considered when circling to

3. At airports without a control tower, it may be
desirable to fly over the airport to observe wind and
turn indicators and other traffic which may be on the
runway or flying in the vicinity of the airport.

AC 90-66A, Recommended Standards Traffic patterns for Aeronautical
Operations at Airports without Operating Control Towers.

4. The missed approach point (MAP) varies

depending upon the approach flown. For vertically

guided approaches, the MAP is at the decision

altitude/decision height. Non-vertically guided and

circling procedures share the same MAP and the pilot

determines this MAP by timing from the final

approach fix, by a fix, a NAVAID, or a waypoint.

Circling from a GLS, an ILS without a localizer line

of minima or an RNAV (GPS) approach without an

LNAV line of minima is prohibited.

g. Instrument Approach at a Military Field.
When instrument approaches are conducted by civil
aircraft at military airports, they must be conducted in
accordance with the procedures and minimums
approved by the military agency having jurisdiction
over the airport.

5-4-21. Missed Approach

a. When a landing cannot be accomplished, advise
ATC and, upon reaching the missed approach point
defined on the approach procedure chart, the pilot
must comply with the missed approach instructions
for the procedure being used or with an alternate
missed approach procedure specified by ATC.
b. Obstacle protection for missed approach is
predicated on the missed approach being initiated at
the decision altitude/height (DA/H) or at the missed
approach point and not lower than minimum descent
altitude (MDA). A climb gradient of at least 200 feet
per nautical mile is required, (except for Copter
approaches, where a climb of at least 400 feet per
nautical mile is required), unless a higher climb

gradient is published in the notes section of the

approach procedure chart. When higher than standard

climb gradients are specified, the end point of the

non-standard climb will be specified at either an
altitude or a fix. Pilots must preplan to ensure that the
aircraft can meet the climb gradient (expressed in feet
per nautical mile) required by the procedure in the
event of a missed approach, and be aware that flying
at a higher than anticipated ground speed increases
the climb rate requirement (feet per minute). Tables
for the conversion of climb gradients (feet per
nautical mile) to climb rate (feet per minute), based
on ground speed, are included on page D1 of the U.S.
Terminal Procedures booklets. Reasonable buffers
are provided for normal maneuvers. However, no

Arrival Procedures 5-4-55

Page 391 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   390 -- Page 391 -- 392