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AIM

4/20/23

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

Section 7. Operational Policy/Procedures for the Gulf of

Mexico 50 NM Lateral Separation Initiative

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1. Introduction and General Policies

a.

Air traffic control (ATC) may apply 50 nautical mile (NM) lateral separation (i.e., lateral spacing) between

airplanes authorized for Required Navigation Performance (RNP) 10 or RNP 4 operating in the Gulf of Mexico.
50 NM lateral separation may be applied in the following airspace:

1.

Houston Oceanic Control Area (CTA)/Flight Information Region (FIR).

2.

Gulf of Mexico portion of the Miami Oceanic CTA/FIR.

3.

Monterrey CTA.

4.

Merida High CTA within the Mexico FIR/UTA.

b.

Within the Gulf of Mexico airspace described above, pairs of airplanes whose flight plans indicate approval

for PBN and either RNP 10 or RNP 4 may be spaced by ATC at lateral intervals of 50 NM. ATC will space any
airplane without RNP 10 or RNP 4 capability such that at least 90 NM lateral separation is maintained with other
airplanes in the Miami Oceanic CTA, and at least 100 NM separation is maintained in the Houston, Monterrey,
and Merida CTAs.

c.

The reduced lateral separation allows more airplanes to fly on optimum routes/altitudes over the Gulf of

Mexico.

d.

50 NM lateral separation is not applied on routes defined by ground navigation aids or on Gulf RNAV

Routes Q100, Q102, or Q105.

e.

Useful information for flight planning and operations over the Gulf of Mexico, under this 50 NM lateral

separation policy, as well as information on how to obtain RNP 10 or RNP 4 authorization, can be found in the
West Atlantic, Gulf of Mexico, and Caribbean Resource Guide for U.S. Operators located at: 
https://www.faa.gov/headquartersoffices/avs/wat-gomex-and-caribbean-resource-guide.

f.

Pilots should use Strategic Lateral Offset Procedures (SLOP) in the course of regular operations within the

Gulf of Mexico CTAs. SLOP procedures and limitations are published in the U.S. Aeronautical Information
Publication (AIP), ENR Section 7.1, General Procedures; Advisory Circular (AC) 91

70, Oceanic and Remote

Continental Airspace Operations; and ICAO Document 4444, Procedures for Air Navigation Services – Air
Traffic Management.

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2. Accommodating Non

RNP 10 Aircraft

a.

Operators not authorized for RNP 10 or RNP 4 may still file for any route and altitude within the Gulf of

Mexico CTAs. However, clearance on the operator’s preferred route and/or altitude will be provided as traffic
allows for 90 or 100 NM lateral separation between the non

RNP 10 aircraft and any others. Priority will be

given to RNP 10 or RNP 4 aircraft.

b.

Operators of aircraft not authorized RNP 10 or RNP 4 must include the annotation “RMK/NONRNP10”

in Item 18 of their ATC flight plan.

c.

Pilots of non

RNP 10 aircraft are to remind ATC of their RNP status; i.e., report “negative RNP 10” upon

initial contact with ATC in each Gulf CTA.

d.

Operators will likely benefit from the effort they invest to obtain RNP 10 or RNP 4 authorization, provided

they are flying aircraft equipped to meet RNP 10 or RNP 4 standards.

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3. Obtaining RNP 10 or RNP 4 Operational Authorization

a.

For U.S. operators, AC 90

105, Approval Guidance for RNP Operations and Barometric Vertical

Navigation in the U.S. National Airspace System and in Oceanic and Remote Continental Airspace, provides