background image

AIM

10/12/17

5

−2−7

Departure Procedures

3.

Design and publish a specific departure route;

or

4.

A combination or all of the above.

e.

What criteria is used to provide obstruction

clearance during departure?

1.

Unless specified otherwise, required obstacle

clearance for all departures, including diverse, is
based on the pilot crossing the departure end of the
runway at least 35 feet above the departure end of
runway elevation, climbing to 400 feet above the
departure end of runway elevation before making the
initial turn, and maintaining a minimum climb
gradient of 200 feet per nautical mile (FPNM), unless
required to level off by a crossing restriction, until the
minimum IFR altitude. A greater climb gradient may
be specified in the DP to clear obstacles or to achieve
an ATC crossing restriction. If an initial turn higher
than 400 feet above the departure end of runway
elevation is specified in the DP, the turn should be
commenced at the higher altitude. If a turn is
specified at a fix, the turn must be made at that fix.
Fixes may have minimum and/or maximum crossing
altitudes that must be adhered to prior to passing the
fix. In rare instances, obstacles that exist on the
extended runway centerline may make an “early
turn” more desirable than proceeding straight ahead.
In these cases, the published departure instructions
will include the language “turn left(right) as soon as
practicable.” These departures will also include a
ceiling and visibility minimum of at least 300 and 1.
Pilots encountering one of these DPs should preplan
the climb out to gain altitude and begin the turn as
quickly as possible within the bounds of safe
operating practices and operating limitations. This
type of departure procedure is being phased out.

NOTE

“Practical” or “feasible” may exist in some existing
departure text instead of “practicable.”

2.

ODPs, SIDs, and DVAs assume normal

aircraft performance, and that all engines are
operating. Development of contingency procedures,
required to cover the case of an engine failure or other
emergency in flight that may occur after liftoff, is
the responsibility of the operator. (More detailed
information on this subject is available in Advisory
Circular AC 120

−91, Airport Obstacle Analysis, and

in the “Departure Procedures” section of chapter 2 in
the Instrument Procedures Handbook,
FAA

−H−8083−16.)

3.

The 40:1 obstacle identification surface

(OIS) begins at the departure end of runway (DER)
and slopes upward at 152 FPNM until reaching the
minimum IFR altitude or entering the en route
structure. This assessment area is limited to 25 NM
from the airport in nonmountainous areas and 46 NM
in designated mountainous areas. Beyond this
distance, the pilot is responsible for obstacle
clearance if not operating on a published route, if
below (having not reached) the MEA or MOCA of a
published route, or an ATC assigned altitude. See
FIG 5

−2−1. (Ref 14 CFR 91.177 for further

information on en route altitudes.)

NOTE

ODPs are normally designed to terminate within these
distance limitations, however, some ODPs will contain
routes that may exceed 25/46 NM; these routes will ensure
obstacle protection until reaching the end of the ODP.

4.

Obstacles that are located within 1 NM of the

DER and penetrate the 40:1 OCS are referred to as
“low, close

−in obstacles.” The standard required

obstacle clearance (ROC) of 48 feet per NM to clear
these obstacles would require a climb gradient greater
than 200 feet per NM for a very short distance, only
until the aircraft was 200 feet above the DER. To
eliminate publishing an excessive climb gradient, the
obstacle AGL/MSL height and location relative to the
DER is noted in the “Take

−off Minimums and

(OBSTACLE) Departure Procedures” section of a
given Terminal Procedures Publication (TPP)
booklet.

(a)

Pilots must refer to the TPP booklet  or the

Graphic ODP for information on these obstacles.
These obstacle notes will no longer be published on
SID. Pilots assigned a SID for departure must refer to
the airport entry in the TPP to obtain information on
these obstacles.

(b)

The purpose of noting obstacles in the

“Take

−off Minimums and (OBSTACLE) Departure

Procedures” section of the TPP is to identify the
obstacle(s) and alert the pilot to the height and
location of the obstacle(s) so they can be avoided.
This can be accomplished in a variety of ways; for
example, the pilot may be able to see the obstruction
and maneuver around the obstacle(s) if necessary;
early liftoff/climb performance may allow the
aircraft to cross well above the obstacle(s); or if the
obstacle(s) cannot be visually acquired during
departure, preflight planning should take into account
what turns or other maneuver may be necessary
immediately after takeoff to avoid the obstruction(s).

9/13/18

AIM