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AIM

10/12/17

5

−4−25

Arrival Procedures

approach and missed approach, except that step down
waypoints may not be included in some TSO

−C129

receiver databases. Included in the database, in most
receivers, is coding that informs the navigation
system of which WPs are fly

−over (FO) or fly−by

(FB). The navigation system may provide guidance
appropriately 

− including leading the turn prior to a

fly

−by WP; or causing overflight of a fly−over WP.

Where the navigation system does not provide such
guidance, the pilot must accomplish the turn lead or
waypoint overflight manually. Chart symbology for
the FB WP provides pilot awareness of expected
actions. Refer to the legend of the U.S. Terminal
Procedures books.

(e)

TAAs are described in paragraph 5

−4−5d,

Terminal Arrival Area (TAA). When published, the
RNAV chart depicts the TAA areas through the use of
“icons” representing each TAA area associated with
the RNAV procedure (See FIG 5

−4−6). These icons

are depicted in the plan view of the approach chart,
generally arranged on the chart in accordance with
their position relative to the aircraft’s arrival from the
en route structure. The WP, to which navigation is
appropriate and expected within each specific TAA
area, will be named and depicted on the associated
TAA icon. Each depicted named WP is the IAF for
arrivals from within that area. TAAs may not be used
on all RNAV procedures because of airspace
congestion or other reasons.

(f) Hot and Cold Temperature Limitations.

A minimum and maximum temperature limitation
is published on procedures which authorize Baro

VNAV operation. These temperatures represent the
airport temperature above or below which Baro

VNAV is not authorized to LNAV/VNAV minimums.
As an example, the limitation will read: “Uncom-
pensated Baro

−VNAV NA below −8_C (+18_F) or

above 47_C (117_F).” This information will be found
in the upper left hand box of the pilot briefing. When
the temperature is above the high temperature or
below the low temperature limit, Baro

−VNAV may

be used to provide a stabilized descent to the LNAV
MDA; however, extra caution should be used in the
visual segment to ensure a vertical correction is not
required. If the VGSI is aligned with the published
glidepath, and the aircraft instruments indicate on
glidepath, an above or below glidepath indication on
the VGSI may indicate that temperature error is
causing deviations to the glidepath. These deviations

should be considered if the approach is continued
below the MDA.

NOTE

Many systems which apply Baro

−VNAV temperature

compensation only correct for cold temperature. In this
case, the high temperature limitation still applies. Also,
temperature compensation may require activation by
maintenance personnel during installation in order to be
functional, even though the system has the feature. Some
systems may have a temperature correction capability, but
correct the Baro

−altimeter all the time, rather than just on

the final, which would create conflicts with other aircraft
if the feature were activated. Pilots should be aware of
compensation capabilities of the system prior to
disregarding the temperature limitations.

NOTE

Temperature limitations do not apply to flying the
LNAV/VNAV line of minima using approach certified
WAAS receivers when LPV or LNAV/VNAV are annunci-
ated to be available.

(g) WAAS Channel Number/Approach ID.

The WAAS Channel Number is an optional
equipment capability that allows the use of a 5

−digit

number to select a specific final approach segment
without using the menu method. The Approach ID is
an airport unique 4

−character combination for

verifying the selection and extraction of the correct
final approach segment information from the aircraft
database. It is similar to the ILS ident, but displayed
visually rather than aurally. The Approach ID
consists of the letter W for WAAS, the runway
number, and a letter other than L, C or R, which could
be confused with Left, Center and Right, e.g., W35A.
Approach IDs are assigned in the order that WAAS
approaches are built to that runway number at that
airport. The WAAS Channel Number and Approach
ID are displayed in the upper left corner of the
approach procedure pilot briefing.

(h)

At locations where outages of WAAS

vertical guidance may occur daily due to initial
system limitations, a negative W symbol (

) will be

placed on RNAV (GPS) approach charts. Many of
these outages will be very short in duration, but may
result in the disruption of the vertical portion of the
approach. The 

 symbol indicates that NOTAMs or

Air Traffic advisories are not provided for outages
which occur in the WAAS LNAV/VNAV or LPV
vertical service. Use LNAV or circling minima for
flight planning at these locations, whether as a
destination or alternate. For flight operations at these
locations, when the WAAS avionics indicate that

2/28/19

AIM