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AIM

10/12/17

5−4−24

Arrival Procedures

established. Obstacle clearance is provided to allow

a momentary descent below DA while transitioning

from the final approach to the missed approach. The

aircraft is expected to follow the missed instructions

while continuing along the published final approach

course to at least the published runway threshold

waypoint or MAP (if not at the threshold) before

executing any turns.

(b) Minimum Descent Altitude (MDA) has

been in use for many years, and will continue to be

used for the LNAV only and circling procedures.

(c) Threshold Crossing Height (TCH) has

been traditionally used in “precision” approaches as

the height of the glide slope above threshold. With

publication of LNAV/VNAV minimums and RNAV

descent angles, including graphically depicted

descent profiles, TCH also applies to the height of the

“descent angle,” or glidepath, at the threshold. Unless

otherwise required for larger type aircraft which may

be using the IAP, the typical TCH is 30 to 50 feet.

6. The  MINIMA FORMAT will also change

slightly.

(a) Each line of minima on the RNAV IAP is

titled to reflect the level of service available; e.g.,

GLS, LPV, LNAV/VNAV, LP, and LNAV. CIR-

CLING minima will also be provided.

(b) The minima title box indicates the nature

of the minimum altitude for the IAP. For example:

(1) DA  will be published next to the

minima line title for minimums supporting vertical

guidance such as for GLS, LPV or LNAV/VNAV.

(2) MDA will be published as the minima

line on approaches with lateral guidance only, LNAV,

or LP. Descent below the MDA must meet the

conditions stated in 14 CFR Section 91.175.

(3) Where two or more systems, such as

LPV and LNAV/VNAV, share the same minima, each

line of minima will be displayed separately.

7. Chart Symbology changed slightly to

include:

(a) Descent Profile. The published descent

profile and a graphical depiction of the vertical path

to the runway will be shown. Graphical depiction of

the RNAV vertical guidance will differ from the

traditional depiction of an ILS glide slope (feather)

through the use of a shorter vertical track beginning

at the decision altitude.

(1) It is FAA policy to design IAPs with

minimum altitudes established at fixes/waypoints to

achieve optimum stabilized (constant rate) descents

within each procedure segment. This design can

enhance the safety of the operations and contribute

toward reduction in the occurrence of controlled

flight into terrain (CFIT) accidents. Additionally, the

National Transportation Safety Board (NTSB)

recently emphasized that pilots could benefit from

publication of the appropriate IAP descent angle for

a stabilized descent on final approach. The RNAV

IAP format includes the descent angle to the

hundredth of a degree; e.g., 3.00 degrees. The angle

will be provided in the graphically depicted descent

profile.

(2) The stabilized approach may be per-

formed by reference to vertical navigation

information provided by WAAS or LNAV/VNAV

systems; or for LNAV−only systems, by the pilot

determining the appropriate aircraft attitude/

groundspeed combination to attain a constant rate

descent which best emulates the published angle. To

aid the pilot, U.S. Government Terminal Procedures

Publication charts publish an expanded Rate of

Descent Table on the inside of the back hard cover for

use in planning and executing precision descents

under known or approximate groundspeed

conditions.

(b) Visual Descent Point (VDP). A VDP

will be published on most RNAV IAPs. VDPs apply

only to aircraft utilizing LP or LNAV minima, not

LPV or LNAV/VNAV minimums.

(c) Missed Approach Symbology. In order

to make missed approach guidance more readily

understood, a method has been developed to display

missed approach guidance in the profile view through

the use of quick reference icons. Due to limited space

in the profile area, only four or fewer icons can be

shown. However, the icons may not provide

representation of the entire missed approach

procedure. The entire set of textual missed approach

instructions are provided at the top of the approach

chart in the pilot briefing.  (See FIG 5−4−6).

(d) Waypoints. All RNAV or GPS stand−

alone IAPs are flown using data pertaining to the

particular IAP obtained from an onboard database,

including the sequence of all WPs used for the

3/15/07

7110.65R CHG 2

AIM

2/28/19