ENR 7.4 Operational Policy 50 NM Lateral Separation

  1. Houston and Miami Oceanic Airspace
    1. The FAA and the Mexican air traffic services (ATS) providers have implemented 50 NM lateral separation between RNP 10 or RNP 4 aircraft operating in Gulf of Mexico oceanic airspace.
    2. Fifty (50) NM lateral separation is implemented in the Houston Oceanic CTA/FIR, the Gulf of Mexico portion of the Miami Oceanic CTA/FIR, the Monterrey CTA, and the Merida CTA within the Mexico FIR/UTA.
    3. RNAV routes within Houston Oceanic airspace are spaced a minimum of 50 NM to support this reduced lateral separation in the Gulf of Mexico.
    4. Information useful for flight planning and operations within the Gulf of Mexico under this 50 NM lateral separation initiative can be found in the West Atlantic Route System, Gulf of Mexico, and Caribbean Resource Guide for U.S. Operators located at www.faa.gov/about/office_org/headquarters_offices/avs/offices/afx/afs/afs400/afs410/media/WATRS.pdf. The Guide can also be found through a web search for “WATRS, GOMEX, Caribbean Resource Guide.”
      1. The web page contains detailed guidance on operator and aircraft authorization for RNP 10 or RNP 4 and includes Job Aids with FAA and ICAO document references.

        NOTE-

        For operations in the Atlantic portion of the Miami Oceanic CTA, or the San Juan CTA/FIR, please review ENR 7.4 Paragraph 5. New York Oceanic Airspace (for information pertaining to the application of 50 NM lateral separation throughout the West Atlantic Route System).

    5. The 50 NM lateral separation is applied at all altitudes above the floor of controlled airspace. Lateral separation of 100 NM will continue to be provided in the Houston Oceanic, Monterrey, and Merida CTA/FIRs to aircraft not authorized RNP 10 or RNP 4. Similarly, those aircraft will experience 90 NM lateral separation in Miami Oceanic CTA/FIR.
    6. 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:
      1. Routes that are flown by reference to ICAO standard ground-based navigation aids (VOR, VOR/DME, NDB); and
      2. Special Area Navigation (RNAV) routes Q100, Q102 and Q105 in the Houston, Jacksonville and Miami CTAs.
    7. Provisions for Accommodation of Non- RNP 10 Aircraft (Not Authorized RNP 10 or RNP 4).
      1. Operators of Non-RNP 10 aircraft must:
      2. Annotate ICAO flight plan Item 18 as follows:
        1. “RMK/NON-RNP10” (no space between letters and numbers).
        2. Use of flight plan item 18 codes “PBN/A1” or “PBN/L1” are restricted to operators and aircraft specifically authorized for RNP 10 or RNP 4, as applicable.
      3. Pilots of non-RNP 10 aircraft that operate in GoMex CTAs must report the lack of authorization by stating “Negative RNP 10":
        1. On initial call to ATC in a Gulf of Mexico CTA; or
        2. When approval status is requested by the controller (See paragraph 1.13.1.3).
      4. Non-RNP 10 operators/aircraft may file any route at any altitude in a Gulf of Mexico 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 non-RNP 10 aircraft.
      5. Non-RNP 10 aircraft should plan on completing their climb to or descent from higher FLs within radar coverage, if possible.
      6. 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 Gulf of Mexico CTAs should obtain authorization for RNP 10 or RNP 4 and annotate the ICAO flight plan accordingly.

        NOTE-

        RNP 10 is the minimum Navigation Specification (NavSpec) required for the application of 50 NM lateral separation. RNP 4 is an operator option; operators/aircraft authorized RNP 4 are not required to also obtain RNP 10 authorization.

    8. RNP 10 or RNP 4 Authorization Policy and Procedures for Aircraft and Operators
      1. The following is ICAO guidance on the state authority responsible for authorizations such as RNP 10, RNP 4, and RVSM:
        1. International commercial operators:
          The State of Registry makes the determination that the aircraft meets the applicable RNP requirements. The State of Operator issues operating authority (for example, Operations Specifications (OpSpecs)).
        2. International general aviation (IGA) operators:
          The State of Registry makes the determination that the aircraft meets the applicable RNP requirements and issues operating authority (for example, Letter of Authorization (LOA)).
    9. Guidance Material.
      1. FAA Advisory Circular (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 operational approval guidance for RNP 4 and 10. It identifies minimum aircraft capabilities and operator procedural and training requirements in order to qualify for RNP 4 or 10. AC 90-105 is consistent with the ICAO PBN Manual discussed below. Pertinent FAA and ICAO documents are posted online in the West Atlantic Route System, Gulf of Mexico and Caribbean Resource Guide for U.S. Operators described in paragraph 1.4.
      2. ICAO Performance-based Navigation (PBN) Manual (ICAO Doc 9613). Guidance for authorization of RNP 10 and RNP 4 is provided in ICAO Doc 9613. RNP 10 is addressed in Volume II, Part B; Chapter 1. RNP 4 is addressed in Volume II, Part C; Chapter 1.
      3. Operators and authorities are encouraged to use the RNP 10 or RNP 4 Job Aids posted on the FAA Resource Guide for U.S. Operators described in paragraph 1.4. For U.S. operators, a set of RNP 10 and RNP 4 Job Aids provides references to FAA documents. An RNP 4 Job Aid, which references the ICAO PBN Manual, is also available on the ICAO European and North Atlantic Office website. These Job Aids address the operational and airworthiness elements of aircraft and operator authorization and provide references to appropriate document paragraphs. The Job Aids provide a method for operators to develop and authorities to track the operator/aircraft program elements required for RNP 10 or RNP 4 authorization.
    10. Qualification of Aircraft Equipped With a Single Long-Range Navigation System (LRNS) for RNP 10 Operations in Gulf of Mexico CTAs.
      1. Single LRNS operations in the Gulf of Mexico, the Caribbean Sea and the other designated areas have been conducted for at least 25 years. Provisions allowing aircraft equipage with a single LRNS for operations in specified oceanic and off-shore areas are contained in the following sections of 14 Code of Federal Regulations (CFR): 91.511, 121.351, 125.203 and 135.165.
      2. The FAA worked with State regulators and ATS providers in the Gulf of Mexico and Caribbean areas, and coordinated with the ICAO North American, Central American, and Caribbean office, to implement a policy allowing single LRNS equipped aircraft, which are also qualified for RNP 10, to take advantage of RNP 10 separation criteria in the Gulf of Mexico CTAs identified in paragraph 1.2 above.
        1. The factors considered in allowing RNP 10 operations in the Gulf of Mexico CTAs with single LRNS equipped aircraft were: the shortness of the legs outside the range of ground navigation aids, the availability of radar and VHF voice coverage in a large portion of Gulf of Mexico airspace, and the absence of adverse events attributed to single LRNS aircraft in Gulf of Mexico operations.
        2. For U.S. operators, operational authorization for both oceanic and RNP 10 operations, when equipped with only a single LRNS, is provided via Operations Specification/Management Specification/Letter of Authorization B054, Oceanic/Remote Continental Airspace Navigation Using a Single Long-Range Navigation System. A U.S. operator must first be issued B054 in order to file a flight plan indicating RNP 10 capability for operations in the Gulf of Mexico CTAs identified in paragraph 1.2 when equipped with only a single LRNS.
      3. Operators should review their Airplane Flight Manual (AFM), AFM Supplement or other appropriate documents and/or contact the airplane or avionics manufacturer to determine the RNP 10 time limit applicable to their aircraft. They will then need to determine its effect, if any, on their operation. Unless otherwise approved, the basic RNP 10 time limit is 6.2 hours between position updates for aircraft on which Inertial Navigation Systems (INS) or Inertial Reference Units (IRU) provide the only source of long range navigation. Extended RNP 10 time limits of 10 hours and greater are already approved for many IRU systems. FAA Advisory Circular 90-105 contains provisions for extending RNP 10 time limits.
    11. Flight Planning Requirements
      1. Operators must make ICAO flight plan annotations in accordance with this paragraph and, if applicable, Paragraph 1.7, Provisions for Accommodation of Non-RNP 10 Aircraft (Not Authorized RNP 10 or RNP 4).
      2. ICAO flight plans must be filed for operation on oceanic routes and areas in the Houston Oceanic CTA/FIR, the Gulf of Mexico portion of the Miami CTA/FIR, the Monterrey CTA and Merida High CTA.
      3. To inform ATC that they have obtained RNP 10 or RNP 4 authorization and are eligible for 50 NM lateral separation, operators must:
        1. Annotate ICAO Flight Plan Item 10 (Equipment) with the letter “R"; and
        2. Annotate Item 18 (Other Information) with, as appropriate, “PBN/A1" for RNP 10 aircraft or “PBN/L1" for RNP 4 aircraft (no space between letters and numbers).

          NOTE-

          The letter “R" indicates that the performance-based navigation specification (for example, RNP 10 or RNP 4) is specified in Item 18 following the indicator “PBN/."

    12. Pilot and Dispatcher Basic and In-Flight Contingency Procedures.
      1. The RNP 10 and RNP 4 Job Aids contain references to pilot and, if applicable, dispatcher procedures contained in Advisory Circular 90-105 and ICAO PBN Manual, Volume II, Parts B and C, Chapter 1.
      2. Pilots should use SLOP procedures in the course of regular oceanic operations. SLOP procedures are published in ICAO Document 4444, 15th Edition, Amendment 2, paragraph 16.5.

        NOTE-

        See ENR 7.1, paragraph 8.

      3. ICAO Doc 4444, Chapter 15, In-flight Contingency Procedures contains important guidance for pilot training programs. Chapter 15 includes Special Procedures for In-flight Contingencies in Oceanic Airspace, as well as Weather Deviation Procedures. Chapter 15 covers in-flight diversion and turn-back scenarios, loss of navigation capability, and procedures to follow for weather avoidance. This critical guidance is reprinted in AIP Section ENR 7.3, the International Notices found in the External Links section of the Federal NOTAM System (FNS) NOTAM Search or Air Traffic Plans and Publications website and FAA Advisory Circular 91-70, Oceanic and Remote Continental Airspace Operations.
      4. When pilots suspect a navigation system malfunction, in addition to the actions suggested in ICAO Doc. 4444, Chapter 15, the following actions should be taken:
        1. Immediately inform ATC of navigation system malfunction or failure;
        2. Accounting for wind drift, fly magnetic compass heading to maintain track; and
        3. Request radar vectors from ATC, when available.
    13. Pilot Report of Non-RNP 10 Status
      1. The pilot must report the lack of RNP 10 or RNP 4 status in accordance with the following:
        1. When the operator/aircraft is not authorized RNP 10 or RNP 4 (See paragraph 1.7.)
        2. If approval status is requested by the controller:
        3. The pilot must communicate approval status using the following phraseology in TBL ENR 7.4-1.

          TBL ENR 7.4-1

          Controller Request

          Pilot Response

          [call sign]
          “CONFIRM RNP 10
          OR 4 APPROVED"

          “AFFIRM RNP 10
          APPROVED"
          or
          “AFFIRM RNP 4
          APPROVED"
          as appropriate; 
          or
          “NEGATIVE RNP 10"

  2. Oakland Oceanic Airspace
    1. The application of 50 NM lateral separation minima between aircraft authorized RNP 10 or RNP 4 is supported.
    2. RNP 10 is required for all aircraft operating in the Central East Pacific (CEP) fixed track system and Pacific Organized Track System (PACOTS).
    3. Non-RNP 10 approved aircraft may file via random track, at any altitude, at least 100 NM from any PACOTS track.
  3. Anchorage Oceanic FIR
    1. The application of 50 NM lateral separation minima between aircraft authorized RNP 10 or RNP 4 is supported.
    2. Non-RNP 10 approved aircraft may file via random track, at any altitude, at least 100 NM from the North Pacific (NOPAC) fixed track system. Aircraft entering the NOPAC should flight plan in accordance with Notices contained in the Alaska Chart Supplement.
  4. Anchorage Arctic FIR
    1. The application of 50 NM lateral separation minima between aircraft authorized RNP 10 is supported.
  5. New York Oceanic Airspace
    1. ATC applies 50 NM lateral separation between aircraft authorized RNP 10 or RNP 4 within the West Atlantic Route System (WATRS) (that is, New York Oceanic West airspace). ATC similarly applies 50 NM lateral separation in the Atlantic portion of the Miami Oceanic CTA as well as the San Juan CTA/FIR. ATC may apply 50 NM lateral separation between aircraft authorized RNP 10 or RNP 4 in airspace outside of WATRS (that is, New York Oceanic East).
    2. Aircraft authorized RNP 10 or RNP 4 will have a better chance of obtaining their preferred routing and altitude in the most densely used airspace (that is, below FL 410) because of their ability to participate in ATC's use of 50 NM lateral separation. Non-RNP 10 or non-RNP 4 aircraft will be spaced at least 90 NM laterally from other aircraft.
    3. ATC will not apply 50 NM lateral separation on routes that are defined by reference to ICAO standard ground-based navigation aids. In addition, 50 NM lateral separation is not applied to aircraft on the following route segments, at and above FL 310, because the routes are considered within ATC radar and VHF radio coverage:
      1. M201 between BAHAA and PAEPR, and
      2. L453 between PAEPR and AZEZU

        NOTE-

        SLOP is not to be used while flying these route segments.

    4. Flight plan filing and addressing requirements are detailed in ENR 7.1, paragraphs 2 and 3.
    5. Operators of aircraft not authorized RNP 10 or RNP 4 are expected to follow the procedures in ENR 7.4 paragraphs 1. 7 and 1.13 for alerting ATC of their RNP status. Those operators are expected to indicate their “non-RNP 10” status in Item 18 of their ATC flight plan. In addition, pilots are expected to inform ATC of their “non-RNP 10” status on initial call to ATC on WATRS routes and when reading back a clearance to descend through FL 410.
    6. Filing a flight plan for, and conducting operations under, RNP 10 or RNP 4 navigation specifications require the aircraft to be equipped with two operable long-range navigation systems (LRNS). Operators who indicate RNP 10 or RNP 4 capability on their ATC flight plans, and subsequently experience a LRNS failure while operating on a WATRS route, must alert ATC to this failure. If the pilot believes the aircraft can continue to be navigated within 10 NM of the cleared route with the single LRNS, ATC should be informed; as such, ATC may continue the aircraft on the cleared route.
    7. In the event of LRNS failure prior to joining a WATRS route, pilots must inform ATC of the failure and ensure ATC is aware the aircraft is no longer qualified for the RNP level indicated in the flight plan. In addition to this notification, pilots should request ATC amend their flight plan to remove the RNP capability indication in Item 18 of the flight plan.
    8. Information regarding operations in WATRS can be found in the West Atlantic Route System, Gulf of Mexico, and Caribbean Resource Guide for U.S. Operators which is available at: 
      www.faa.gov/about/office_org/headquarters_offices/avs/offices/afx/afs/afs400/afs410/media/WATRS.pdf
  6. Provisions for Accommodation of Non-RNP 10 Aircraft (Not Authorized RNP 10 or RNP 4)
    The guidance contained in paragraphs 1.7 and 1.13 of this section is applicable to all operations using Non-RNP 10 aircraft throughout the airspace covered by this document.
  7. RNP 10 or RNP 4 Authorization Policy and Procedures for Aircraft and Operators
    The guidance contained in paragraphs 1.8 and 1.9 of this section is applicable to operations throughout the airspace covered by this document.
  8. Flight Planning Requirements
    The guidance contained in paragraphs 1.7 and 1.11 of this section is applicable to operations throughout the airspace covered by this document.
  9. Pilot and Dispatcher Basic and In-Flight Contingency Procedures
    Information and guidance pertaining to in-flight contingency procedures, applicable in all the oceanic airspace covered by this AIP are provided in ENR 7.4, paragraph 1.12 as well as section ENR  7.3.