Eddie Sez:

Of the current RNP designations, RNP-4 is the specification designed for oceanic and remote continental navigation applications. While RNP-10 and North Atlantic High Level Airspace (the old MNPS) are also used, they are not true Performance Based Navigation standards. (We can expect them to go away in the future.)

As of summer 2016, only a handful of places in the world say RNP-4 is required but they all have work arounds in place if you are RNP-10 authorized. If you plan on oceanic or remote operations, you will need an LOA when operating under 14 CFR 91. If you are operating under 14 CFR 135, you will need OpSpec B036.

What follows comes from the references shown below. Where I think it helpful, I've added my own comments in blue.


Location

Asia

[ICAO Doc 7030, §MID/ASIA, ¶4.1.2.1.2] For flights on designated controlled oceanic routes or areas within the Auckland Oceanic, Brisbane, Fukuoka, Honiara, Melbourne, Nauru, New Zealand and Port Moresby FIRs, a longitudinal separation minimum of 55.5 km (30 NM) derived by RNAV may be applied between RNAV-equipped aircraft approved to RNP 4 or better, in accordance with the provisions of the PANS-ATM, 5.4.2.6.

Pacific

[ICAO Doc 7030, §PAC, ¶4.1.2.1.2] For flights on designated controlled oceanic routes or areas within the Anchorage Arctic, Anchorage Continental, Anchorage Oceanic, Auckland Oceanic, Nadi, Oakland Oceanic and Tahiti FIRs, a longitudinal separation minimum of 55.5 km (30 NM) derived by RNAV may be applied between RNAV-equipped aircraft approved to RNP 4 or better, in accordance with the provisions of the PANS-ATM, 5.4.2.6.

In both the Asia and Pacific instances, the 30 NM longitudinal separation "may be applied." If you do not have RNP-4 authorization the following PANS-ATM provisions are cited:

RNAV Provisions

[ICAO Doc 4444, ¶5.4.2.6] LONGITUDINAL SEPARATION MINIMA BASED ON DISTANCE USING RNAV WHERE RNP IS SPECIFIED

5.4.2.6.2.2 Direct controller-pilot communications shall be maintained while applying a distance-based separation minima. Direct controller-pilot communications shall be voice or CPDLC. The communication criteria necessary for CPDLC to satisfy the requirement for direct controller-pilot communications shall be established by an appropriate safety assessment.

5.4.2.6.3 Longitudinal distance-based separation minima in an RNP RNAV environment not using ADS

5.4.2.6.3.1 For aircraft cruising, climbing or descending on the same track, the following separation minimum may be used:

Separation minimum RNP type Communication requirement Surveillance requirement Distance verification requirements
93 km (50NM) 10 Direct controller-pilot communications Procedure position reports At least every 24 minutes

5.4.2.6.4 Longitudinal distance-based separation minima in 5.4.2.6.4 an RNP RNAV environment using ADS

5.4.2.6.4.3 For aircraft cruising, climbing or descending on the same track, the following separation minima may be used:

Separation minimum RNP type Maximum ADS periodic reporting interval
93 km (50NM) 10 27 minutes
93 km (50NM) 4 32 minutes
55.5 km (30NM) 4 14 minutes

If you do not have ADS and are not RNP-4 authorized, the controllers have the option of accepting you but using increased separation standards provided: you are RNP-10 qualified, you are in direct communications with the controller, and you make position reports at least every 24 minutes.


Accuracy / Performance Standards

System Performance, Monitoring, and Alerting

[ICAO Doc 9613, Volume II, Part C,¶1.3.3.5]

These requirements are duplicated in Advisory Circular (AC) 20-138( ), Airworthiness Approval of Positioning and Navigation Systems.

Additional Requirements

[ICAO Doc 9613, Volume II, Part C,¶1.3.4.1] It is important to understand that additional requirements will have to be met for operational authorization in RNP 4 airspace or on RNP 4 routes. Controller-pilot data link communications (CPDLC) and automatic dependent surveillance — contract (ADS-C) systems will also be required when the separation standard is 30 NM lateral and/or longitudinal. The on-board navigation data must be current and include appropriate procedures.

This is a potential "gotcha" in the works. You can have an OpSpec/MSpec/LOA for RNP-4 authorization without CPDLC and ADS. (Some POIs will not permit this, but some will.) There are locations in the world where the requirement for RNP-4 authorization assumes CPDLC and ADS.


Qualification Criteria / Operational Approval

Qualification Criteria

[AC 90-105A, App. F, ¶F.2]

Operational Approval - 14 CFR 91

[AC 90-105A]

Operational Approval - 14 CFR 91K, 121, 125, 129, and 135

[AC 90-105A] Parts 91K, 121, 125, 129, and 135 Operators. Title 14 CFR parts 91K, 121, 125, 129, and 135 operators receive approval to fly RNP operations as described in this AC via operations specifications (OpSpecs), management specifications (MSpecs), or LOAs as follows:

[FAA Order 8900.10 Vol 3, Chapter 18, Part B, §B036, ¶k)] OpSpec/MSpec Entries.

  1. For RNP 4 operations, an aircraft must meet a cross-track keeping accuracy and along-track positioning accuracy of no greater than +7.4 km (4 NM) for 95 percent of the flight time. Different routes that require RNP-4 may have different separation, equipment, and communications requirements. It is possible in the future that a route or airspace could be established that would require RNP-4 navigation capability with VHF communication and radar. Some examples of routes that require RNP-4 are:
    • Australian Tasman Sea; detailed guidance is contained in Australian Government, Civil Aviation Authority, AC 91U-3(0), Required Navigation Performance 4 (RNP-4) Operational Certificate;

    • Easter Russia, the Magadan region; requires FANS 1/A-equiped aircraft; and
    • "Easter Russia" is probably a typo, most likely means eastern Russia.

    • Western region of China and north of the Himalayas, Route 888; because of the remoteness of the area, RNP-4 CPDLC, and ADS are required.
  2. Eligibility of aircraft and certification of its navigation equipment for RNP-4 must be determined:
    • For RNP-4 operations in oceanic or remote airspace, at least two fully serviceable independent LRNS, with integrity such that the navigation system does not provide misleading information, must be fitted to the aircraft. These will form part of the basis upon which RNP-4 operational approval is granted;

    • For aircraft incorporating GPS, AC 20-138A or equivalent documents provide an acceptable means of complying with installation requirements for aircraft that use but do not integrate the GNSS output with that of other sensors. AC 20-130A describes an acceptable means of compliance for multi-sensor navigation systems that incorporate GPS; and

    • Flightcrew training and operating procedures for the navigation systems to be used must be identified by the operator.

Example Compliance

Figure: Limitations Extract, from G450 Airplane Flight Manual, §1-03-10, ¶13.]


Book Notes

Portions of this page can be found in the book International Flight Operations, Part III, Chapter 9.


References

Advisory Circular 20-138D, Positioning and Navigation Systems, 5/8/12, U.S. Department of Transportation

Advisory Circular 90-105A, Approval Guidance for RNP Operations and Barometric Vertical Navigation in the U.S. National Airspace System and in Oceanic and Remote Continental Airspace, 3/7/2016, U.S. Department of Transportation

FAA Orders 8400 and 8900

FAA Order 8400.33, Procedures for Obtaining Authorization for Required Navigation Performance 4 (RNP-4) Oceanic and Remote Area Operations, U.S. Department of Transportation, 9/15/05

ICAO Doc 4444 - Air Traffic Management, Fourteenth Edition, Procedures for Air Navigation Services, International Civil Aviation Organization, 2001 *

ICAO Doc 4444 - Air Traffic Management, Fifteenth Edition, Procedures for Air Navigation Services, International Civil Aviation Organization, 2007 *

* Not all of Doc 4444 seems to have been reproduced in the 15th edition, so you might need to look at the 15th edition and then then 14th edition for some sections.

ICAO Doc 4444 - Amendment No. 1, Procedures for Air Navigation Services, International Civil Aviation Organization, Amendment No. 1, 2007

ICAO Doc 4444 - Amendment No. 2, Procedures for Air Navigation Services, International Civil Aviation Organization, Amendment No. 2, 19/11/09

ICAO Doc 7030 - Regional Supplementary Procedures, International Civil Aviation Organization, 2008

ICAO Doc 9613 - Performance Based Navigation (PBN) Manual, International Civil Aviation Organization, 2008