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

AC 90−105 to evaluate an operator’s application for

RNP 10 or RNP 4 authorization. Authorization to

conduct RNP operations in oceanic airspace is

provided to all U.S. operators through issuance of

Operations Specification (OpSpec), Management

Specification (MSpec), or Letter of Authorization

(LOA) B036, as applicable to the nature of the

operation; for example, Part 121, Part 91, etc.

Operators may wish to review FAA Order 8900.1,

Flight Standards Information Management System,

volume 3, chapter 18, section 4, to understand the

specific criteria for issuing OpSpec, MSpec, and/or

LOA B036.

b. The operator’s RNP 10 or RNP 4 authorization

should include any equipment requirements and

RNP 10 time limits (if operating solely inertial−

based navigation systems), which must be observed

when conducting RNP operations. RNP 4 requires

tighter navigation and track maintenance accuracy

than RNP 10.

4−7−4. Authority for Operations with a

Single Long−Range Navigation System
Operators may be authorized to take advantage of

50 NM lateral separation in the Gulf of Mexico CTAs

when equipped with only a single long−range

navigation system. RNP 10 with a single long−range

navigation system is authorized via OpSpec, MSpec,

or LOA B054. Operators should contact their FSDO

or CMO to obtain information on the specific

requirements for obtaining B054. Volume 3, chapter

18, section 4 of FAA Order 8900.1 provides the

qualification criteria to be used by FAA aviation

safety inspectors in issuing B054.

4−7−5. Flight Plan Requirements

a. In order for an operator with RNP 10 or RNP 4

authorization to obtain 50 NM lateral separation in

the Gulf of Mexico CTAs, and therefore obtain

preferred routing available to RNP authorized

aircraft, the international flight plan form (FAA

7233−4) must be annotated as follows:

1. Item 10a (Equipment) must include the letter


2. Item 18 must include either “PBN/A1” for

RNP 10 authorization or “PBN/L1” for RNP 4


b. Indication of RNP 4 authorization implies the

aircraft and pilots are also authorized RNP 10.

c. Chapter 5, section 1, of this manual includes

information on all flight plan codes. RNP 10 has the

same meaning and application as RNAV 10. They

share the same code.

4−7−6. Contingency Procedures

Pilots operating under reduced lateral separation

must be particularly familiar with, and prepared to

rapidly implement, the standard contingency proce-

dures specifically written for operations when

outside ATC surveillance and direct VHF communi-

cations (for example, the oceanic environment).

Specific procedures have been developed for weather

deviations. Operators should ensure all flight crews

operating in this type of environment have been

provided the standard contingency procedures in a

readily accessible format. The margin for error when

operating at reduced separation mandates correct and

expeditious application of the standard contingency

procedures. These internationally accepted proce-

dures are published in ICAO Document 4444,

chapter 15. The procedures are also reprinted in the

U.S. Aeronautical Information Publication (AIP),

En Route (ENR) Section 7.3, Special Procedures for

In−flight  Contingencies in Oceanic Airspace; and

AC 91−70.


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