Aeronautical Information Manual (AIM), page 317

Index   316 -- Page 317 -- 318

12/10/15                                                                                                         AIM

as possible within the bounds of safe operating prac-        NOTE-
tices and operating limitations. This type of departure      ODPs are normally designed to terminate within these dis-
procedure is being phased out.                               tance 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.
"Practical" or "feasible" may exist in some existing de-
parture text instead of "practicable."                            4. Obstacles that are located within 1 NM of the
     2. ODPs and SIDs assume normal aircraft per-            DER and penetrate the 40:1 OCS are referred to as
formance, and that all engines are operating.                "low, close-in obstacles." The standard required
Development of contingency procedures, required              obstacle clearance (ROC) of 48 feet per NM to clear
to cover the case of an engine failure or other              these obstacles would require a climb gradient greater
emergency in flight that may occur after liftoff, is         than 200 feet per NM for a very short distance, only
the responsibility of the operator. (More detailed           until the aircraft was 200 feet above the DER. To
information on this subject is available in Advisory         eliminate publishing an excessive climb gradient, the
Circular AC 120-91, Airport Obstacle Analysis, and           obstacle AGL/MSL height and location relative to the
in the "Departure Procedures" section of chapter 2 in        DER is noted in the "Take-off Minimums and
the     Instrument       Procedures      Handbook,           (OBSTACLE) Departure Procedures" section of a
FAA-H-8261-1.)                                               given Terminal Procedures Publication (TPP) book-
     3. The 40:1 obstacle identification surface             let. The purpose of this note is to identify the
(OIS) begins at the departure end of runway (DER)            obstacle(s) and alert the pilot to the height and loca-
and slopes upward at 152 FPNM until reaching the             tion of the obstacle(s) so they can be avoided. This
minimum IFR altitude or entering the en route struc-         can be accomplished in a variety of ways, e.g., the
ture. This assessment area is limited to 25 NM from          pilot may be able to see the obstruction and maneuver
the airport in nonmountainous areas and 46 NM in             around the obstacle(s) if necessary; early liftoff/climb
designated mountainous areas. Beyond this distance,          performance may allow the aircraft to cross well
the pilot is responsible for obstacle clearance if not       above the obstacle(s); or if the obstacle(s) cannot be
operating on a published route, if below (having not         visually acquired during departure, preflight plan-
reached) the MEA or MOCA of a published route, or            ning should take into account what turns or other
an ATC assigned altitude. See FIG 5-2-1. (Ref 14             maneuver may be necessary immediately after
CFR 91.177 for further information on en route alti-         takeoff to avoid the obstruction(s).
FIG 5-2-1 Diverse Departure Obstacle Assessment to 25/46 NM Departure Procedures 5-2-7

Page 317 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   316 -- Page 317 -- 318