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Aeronautical Information Manual (AIM), page 316

Index   315 -- Page 316 -- 317



5-2-8. Instrument Departure Procedures
(DP) - Obstacle Departure Procedures
(ODP) and Standard Instrument Departures
(SID)

Instrument departure procedures are preplanned in-
strument flight rule (IFR) procedures which provide

obstruction clearance from the terminal area to the
appropriate en route structure. There are two types of
DPs, Obstacle Departure Procedures (ODPs), printed

either textually or graphically, and Standard Instru-
ment Departures (SIDs), always printed graphically.
All DPs, either textual or graphic may be designed us-
ing either conventional or RNAV criteria. RNAV
procedures will have RNAV printed in the title,
e.g., SHEAD TWO DEPARTURE (RNAV). ODPs
provide obstruction clearance via the least onerous
route from the terminal area to the appropriate en
route structure. ODPs are recommended for obstruc-

tion clearance and may be flown without ATC

clearance unless an alternate departure procedure
(SID or radar vector) has been specifically assigned
by ATC. Graphic ODPs will have (OBSTACLE)
printed in the procedure title, e.g., GEYSR THREE
DEPARTURE (OBSTACLE), or, CROWN ONE

DEPARTURE (RNAV) (OBSTACLE). Standard In-

strument Departures are air traffic control (ATC)

procedures printed for pilot/controller use in graphic

form to provide obstruction clearance and a transition

from the terminal area to the appropriate en route

structure. SIDs are primarily designed for system en-

hancement and to reduce pilot/controller workload.

ATC clearance must be received prior to flying a SID.

All DPs provide the pilot with a way to depart the air-

port and transition to the en route structure safely.

Pilots operating under 14 CFR Part 91 are strongly

encouraged to file and fly a DP at night, during mar-

ginal Visual Meteorological Conditions (VMC) and

Instrument Meteorological Conditions (IMC), when

one is available. The following paragraphs will pro-

vide an overview of the DP program, why DPs are

developed, what criteria are used, where to find them,

how they are to be flown, and finally pilot and ATC

responsibilities.

a. Why are DPs necessary? The primary reason is
to provide obstacle clearance protection information
to pilots. A secondary reason, at busier airports, is to
increase efficiency and reduce communications and
departure delays through the use of SIDs. When an in-
strument approach is initially developed for an
airport, the need for DPs is assessed. The procedure

designer conducts an obstacle analysis to support de-
parture operations. If an aircraft may turn in any
direction from a runway within the limits of the as-
sessment area (see paragraph 5-2-8b3) and remain
clear of obstacles, that runway passes what is called
a diverse departure assessment and no ODP will be

published. A SID may be published if needed for air
traffic control purposes. However, if an obstacle pen-
etrates what is called the 40:1 obstacle identification

surface, then the procedure designer chooses whether
to:

1. Establish a steeper than normal climb gradi-
ent; or
2. Establish a steeper than normal climb gradi-
ent with an alternative that increases takeoff minima
to allow the pilot to visually remain clear of the ob-
stacle(s); or

3. Design and publish a specific departure route;

or

4. A combination or all of the above.
b. 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 run-

way elevation, climbing to 400 feet above the

departure end of runway elevation before making the

initial turn, and maintaining a minimum climb gradi-

ent 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 speci-

fied at a fix, the turn must be made at that fix. Fixes

may have minimum and/or maximum crossing alti-

tudes 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 de-
sirable 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 visi-
bility 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

5-2-6 Departure Procedures

Page 316 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   315 -- Page 316 -- 317