Many reasons exist for executing a missed approach.
The primary reason, of course, is that the required
flight visibility prescribed in the IAP being used does
not exist or the required visual references for the runway
cannot be seen upon arrival at the DA, DH or
MAP. In addition, according to Part 91, the aircraft
must continuously be 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,
and for operations conducted under Part 121 or 135,
unless that descent rate will allow touchdown to occur
within the touchdown zone of the runway of intended
landing. [Figure 5-22] CAT II and III approaches call for
different visibility requirements as prescribed by the
Administrator.
Once descent below the DA, DH, or MDA is begun, a
missed approach must be executed if the required visibility
is lost or the runway environment is no longer
visible, unless the loss of sight of the runway is a result
of normal banking of the aircraft during a circling
approach. A missed approach procedure is also
required upon the execution of a rejected landing for
any reason, such as men and equipment or animals on
the runway, or if the approach becomes unstabilized
and a normal landing cannot be performed. After the
MAP in the visual segment of a nonprecision approach
there may be hazards when executing a missed
approach below the MDA. Any missed approach after a
DA, DH, or MAP below the DA, DH, or MDA involves
additional risk until established on the published
missed approach procedure course and altitude.
At airports with control towers it is common for ATC to
assign alternate missed approach instructions; even so,
pilots should always be prepared to fly the published
Figure 5-21. Determination of Visibility Minimums.
Figure 5-22. Operation Below DA, DH, or MDA.
missed approach. When a missed approach is executed
prior to reaching the MAP, the pilot is required to continue
along the final approach course, at an altitude
above the DA, DH, or MDA, until reaching the MAP
before making any turns. If a turn is initiated prior to
the MAP, obstacle clearance is not guaranteed. It is
appropriate after passing the FAF, and recommended,
where there aren’t any climb restrictions, to begin a
climb to the missed approach altitude without waiting
to arrive at the MAP. Figure 5-23 gives an example of
an altitude restriction that would prevent a climb
between the FAF and MAP. In this situation, the
Orlando Executive ILS or LOC RWY 7 approach altitude
is restricted at the BUVAY 3 DME fix to prevent
aircraft from penetrating the overlying protected airspace
for approach routes into Orlando International
Airport. If a missed approach is initiated before reaching
BUVAY, a pilot may be required to continue
descent to 1,200 feet before proceeding to the MAP and
executing the missed approach climb instructions. In
addition to the missed approach notes on the chart, the
Pilot Briefing Information icons in the profile view
indicate the initial vertical and lateral missed approach
guidance.
The missed approach course begins at the MAP and
continues until the aircraft has reached the designated
fix and a holding pattern has been entered, unless there
is no holding pattern published for the missed
approach. It is common at large airports with high traffic
volume to not have a holding pattern depicted at the
designated fix. [Figure 5-24 on page 5-35] In these
circumstances, the departure controller will issue
further instructions before the aircraft reaches the
final fix of the missed approach course. It is also
common for the designated fix to be an IAF so that
another approach attempt can be made without
having to fly from the holding fix to an IAF.
As shown in Figure 5-25 on page 5-36, there are many
different ways that the MAP can be depicted, depending
on the type of approach. On all approach charts it is
depicted in the profile and planviews by the end of the
solid course line and the beginning of the dotted missed
approach course line for the “top-line”/lowest published
minima. For a precision approach, the MAP is
the point at which the aircraft reaches the DA or DH
while on the glide slope. MAPs on nonprecision
approaches can be determined in many different ways.
If the primary NAVAID is on the airport, the MAP is
normally the point at which the aircraft passes the
NAVAID.
On some nonprecision approaches, the MAP is given as
a fixed distance with an associated time from the FAF to
the MAP based on the groundspeed of the aircraft. A
table on the lower right hand side of the approach chart
shows the distance in NM from the FAF to the MAP and
the time it takes at specific groundspeeds, given in 30-
knot increments. Pilots must determine the approximate
groundspeed and time based on the approach speed and
true airspeed of their aircraft and the current winds along
the final approach course. A clock or stopwatch should
be started at the FAF of an approach requiring this
method. Many nonprecision approaches designate a specific
fix as the MAP. These can be identified by a course
(LOC or VOR) and DME, a cross radial from a VOR, or
an RNAV (GPS) waypoint.
Obstacles or terrain in the missed approach segment
may require a steeper climb gradient than the standard
200 feet per NM. If a steeper climb gradient is
required, a note will be published on the approach chart
plan view with the penetration description and examples
of the required FPM rate of climb for a given
groundspeed (future charting will use climb gradient).
An alternative will normally be charted that allows
using the standard climb gradient. [Figure 5-25 on page
5-36] In this example, if the missed approach climb
requirements cannot be met for the Burbank ILS RWY
8 chart, the alternative is to use the LOC RWY 8 that is
charted separately. The LOC RWY 8, S-8 procedure
has a MDA that is 400 foot higher than the ILS RWY 8,
S-LOC 8 MDA, and meets the standard climb gradient
requirement over the terrain.