background image

6/17/21 

AIM 

Section 7.  Operational Policy/Procedures for the Gulf of 

Mexico 50 NM Lateral Separation Initiative 

4

7

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 Naviga-
tion 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. 

Information useful 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 Route System, Gulf of 
Mexico, and Caribbean Resource Guide for U.S. 
Operators located at: 
https://www.faa.gov/about/office_org/headquar-
ters_offices/avs/offices/afx/afs/afs400/afs410/media 
/watrs.pdf 

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. 

4

7

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/NON-
RNP10” 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. 

4

7

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 the aircraft and operator 
qualification criteria for RNP 10 or RNP 4 
authorizations. FAA personnel at flight standards 
district offices (FSDO) and certificate management 
offices (CMO) will use the guidance contained in 

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

4

7