Aeronautical Information Manual (AIM)

AIM

4/3/14

4−7−2

Operational Policy/Procedures for the Gulf of Mexico 50 NM Lateral Separation Initiative

The current lateral separation minima of 100

NM in the Houston, Monterrey and Merida CTAs,

and 90 NM in the Miami Oceanic CTA will continues

to be applied between aircraft not authorized RNP 10

or RNP 4.

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4. Operation on Routes on the

periphery of the Gulf of Mexico CTAs

Operations on certain routes that fall within the

boundaries of affected CTAs are not affected by the

introduction of 50 NM lateral separation. Operation

on the following routes is not affected:

Routes that are flown by reference to ICAO

standard ground-based navigation aids (VOR,

VOR/DME, NDB).

Special Area Navigation (RNAV) routes Q100,

Q102 and Q105 in the Houston, Jacksonville and

Miami CTAs.

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5. Provisions for Accommodation of

NonRNP10 Aircraft (Aircraft Not Authorized
RNP 10 or RNP 4)

Operators of NonRNP10 aircraft must annotate

ICAO flight plan Item 18 as follows:
“STS/NONRNP10” (no space between letters and

numbers).

Pilots of NonRNP10 aircraft that operate in

GoMex CTA’s must report the lack of authorization

by stating “Negative RNP 10”:

On initial call to ATC in a GoMex CTA:

In read back of a clearance to climb to or

descend from cruise altitude. (See paragraph

4−7−5e.); and

When approval status is requested by the

controller. (See paragraph 4−7−9e.)

Operators of NonRNP10 aircraft must not

annotate ICAO flight plan Item 18 (Other

Information) with “NAV/RNP10” or “NAV/RNP4”,

as shown in paragraph 7, if they have not obtained

RNP 10 or RNP 4 authorization.

NonRNP10 operators/aircraft may file any

route at any altitude in a GoMex CTA. They will be

cleared to operate on their preferred routes and

altitudes as traffic permits. 50 NM lateral separation

will not be applied to NonRNP10 aircraft.

NonRNP10 aircraft are encouraged to operate at

altitudes above those where traffic is most dense (i.e.,

at/above FL 380), if possible. NonRNP10 aircraft

should plan on completing their climb to or descent

from higher FLs within radar coverage, if possible.

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6. Operator Action

In order to maximize operational flexibility provided

by 50 NM lateral separation, operators capable of

meeting RNP 10 or RNP 4 that operate on oceanic

routes or areas in the GoMex CTA’s should obtain

authorization for RNP 10 or RNP 4 and annotate the

ICAO flight plan accordingly.

NOTE

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1. RNP 10 is the minimum “Navigation Specification
(NavSpec)” required for the application of 50 NM lateral
separation. RNP 4 is an operator option. Operators/air-
craft authorized RNP 4 are not required to also obtain
RNP 10 authorization.

2. “RNP navigation specification” (e.g., RNP 10) is the
term adopted in the ICAO Performance-based Navigation
(PBN) Manual (Doc 9613). It replaces the term “RNP
type”.

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7. RNP 10 or RNP 4 Authorization:

Policy and Procedures for Aircraft and
Operators

RNP NavSpecs Applicable To Oceanic Opera-

tions. In accordance with ICAO guidance, RNP 10

and RNP 4 are the only NavSpecs applicable to

oceanic and remote area operations. Other RNAV and

RNP NavSpecs are applicable to continental en route,

terminal area and approach operations.

FAA Documents. The guidance and direction

of FAA Order 8400.12 (as amended) (RNP 10

Operational Authorization) is used to grant RNP 10

authorization to operators and aircraft for which the

FAA is responsible. FAA Order 8400.33 (as

amended) (Procedures for Obtaining Authorization

for RNP 4 Oceanic/Remote Area Operations) is used

to authorize RNP 4. The FAA RNP 10 and RNP 4

orders are consistent with the ICAO PBN Manual

guidance discussed below. FAA and ICAO docu-

ments are posted on the FAA Gulf of Mexico 50 NM

Lateral Separation Initiative Web Page.

ICAO Performance-based Navigation (PBN)

Manual (ICAO Doc 9613). Guidance for authoriza-

tion of RNP 10 and RNP 4 is provided in ICAO Doc

9613. RNP 10 is addressed in Volume II, Part B;