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Aeronautical Information Manual (AIM), page 681

12/10/15 Pilot/Controller Glossary

O
OBSTACLE- An existing object, object of natural
growth, or terrain at a fixed geographical location or
which may be expected at a fixed location within a
prescribed area with reference to which vertical
clearance is or must be provided during flight
operation.
OBSTACLE DEPARTURE PROCEDURE (ODP)-
A preplanned instrument flight rule (IFR) departure
procedure printed for pilot use in textual or graphic
form to provide obstruction clearance via the least
onerous route from the terminal area to the
appropriate en route structure. ODPs are recom-
mended for obstruction clearance and may be flown
without ATC clearance unless an alternate departure
procedure (SID or radar vector) has been specifically
assigned by ATC.
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
(See STANDARD INSTRUMENT
DEPARTURES.)
(Refer to AIM.)

OBSTACLE FREE ZONE- The OFZ is a three
dimensional volume of airspace which protects for
the transition of aircraft to and from the runway. The
OFZ clearing standard precludes taxiing and parked
airplanes and object penetrations, except for
frangible NAVAID locations that are fixed by
function. Additionally, vehicles, equipment, and
personnel may be authorized by air traffic control to
enter the area using the provisions of FAAO JO
7110.65, Para 3-1-5, VEHICLES/EQUIPMENT/
PERSONNEL ON RUNWAYS. The runway OFZ
and when applicable, the inner-approach OFZ, and

the inner-transitional OFZ, comprise the OFZ.

a. Runway OFZ. The runway OFZ is a defined
volume of airspace centered above the runway. The

runway OFZ is the airspace above a surface whose

elevation at any point is the same as the elevation of

the nearest point on the runway centerline. The

runway OFZ extends 200 feet beyond each end of the
runway. The width is as follows:

1. For runways serving large airplanes, the

greater of:

(a) 400 feet, or

(b) 180 feet, plus the wingspan of the most
demanding airplane, plus 20 feet per 1,000 feet of
airport elevation.
2. For runways serving only small airplanes:
(a) 300 feet for precision instrument run-
ways.
(b) 250 feet for other runways serving small
airplanes with approach speeds of 50 knots, or more.
(c) 120 feet for other runways serving small
airplanes with approach speeds of less than 50 knots.
b. Inner-approach OFZ. The inner-approach OFZ
is a defined volume of airspace centered on the
approach area. The inner-approach OFZ applies only
to runways with an approach lighting system. The
inner-approach OFZ begins 200 feet from the runway
threshold at the same elevation as the runway
threshold and extends 200 feet beyond the last light
unit in the approach lighting system. The width of the
inner-approach OFZ is the same as the runway OFZ
and rises at a slope of 50 (horizontal) to 1 (vertical)
from the beginning.
c. Inner-transitional OFZ. The inner transitional
surface OFZ is a defined volume of airspace along the
sides of the runway and inner-approach OFZ and
applies only to precision instrument runways. The
inner-transitional surface OFZ slopes 3 (horizontal)
to 1 (vertical) out from the edges of the runway OFZ
and inner-approach OFZ to a height of 150 feet above
the established airport elevation.
(Refer to AC 150/5300-13, Chapter 3.)
(Refer to FAAO JO 7110.65, Para 3-1-5,
VEHICLES/EQUIPMENT/PERSONNEL ON
RUNWAYS.)

OBSTRUCTION- Any object/obstacle exceeding

the obstruction standards specified by 14 CFR
Part 77, Subpart C.

OBSTRUCTION LIGHT- A light or one of a group

of lights, usually red or white, frequently mounted on

a surface structure or natural terrain to warn pilots of

the presence of an obstruction.

OCEANIC AIRSPACE- Airspace over the oceans of
the world, considered international airspace, where

oceanic separation and procedures per the Interna-

tional Civil Aviation Organization are applied.
Responsibility for the provisions of air traffic control

PCG O-1

Page 681 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   680 -- Page 681 -- 682