North Atlantic Mandates and Trials


Minimum Navigation Performance Standard, MNPS was adopted in 1974 to ensure navigation accuracy and redundancy over the North Atlantic. Generally speaking, MNPS was implemented inside the lateral boundary of Santa Maria Oceanic, Shanwick Oceanic, Reykjavik, Gander Oceanic, and New York Oceanic between FL285 and FL420. On 4 FEB16, the that airspace known as the “North Atlantic Minimum Navigational Specifications Airspace” added the BODO Oceanic FIR and will now designated as the “North Atlantic High Level Airspace” NAT HLA (FL285-420 inclusive). This re-designation excludes the BOTA and SOTA areas of the Shanwick OCA. Beginning in 2013, MNPS began a transition to RNP(RNAV)-10 or RNP-4 replacing MNPS, an approximately 12.6 RNP. For MNPS approvals issued before January 2013, the State of Registry will have to verify that the lateral navigation capability of the aircraft under MNPS RNP(RNAV)-10 or RNP-4 standard. For Approvals issued after January 2015 the navigation system accuracy requirements for NAT MNPSA/HLA operation should only have be based on the PBN specifications, RNP(RNAV)-10 or RNP-4. MNPS Approvals based on MNPS vice the PBN standard of RNP(RNAV)-10 or RNP-4 will no longer be accepted beyond January 2020.

North Atlantic Datalink Mandate, NAT DLM

This has to do with LOA/OpsSpec A056 and your aircraft’s FANS capabilities such as, Controller-Pilot Direct Communication, CPDLC and Automatic Dependent Surveillance ADS-C. The North Atlantic Data Link Mandate, NAT DLM was adopted by the North Atlantic Systems Planning Group in 2013. “NAR DLM, Phase 2” is being implemented in three phases;

  • Phase 2A was implemented on 5FEB15
  • Phase 2B was implemented on 7DEC017
  • Phase 2C is planned for 30JAN20

NAT DLM Phase 2A directed that all aircraft to be fitted with and using FANS 1/A CPDLC and ADS−C equipment if operating between FL 350 to FL 390 (inclusive) inside the NAT organized track system, NAT OTS. This was in effect only during the NAT OTS validity period.

NAT DLM Phase 2B expanded the FANS CPDLC/ADS-C requirement to throughout the ICAO NAT Region between FL 350−FL 390 inclusive. This is where we are now.

NAT DLM Phase 2C will expand the FANS CPDLC/ADS-C requirement once again. This time NAT DLM is expanded to everything, FL290 and above throughout the ICAO NAT Region.

There are some places in the NAT that this DLM does not apply.

  • “ATS Surveillance Airspace”. This means airspace where surveillance is provided by direct SSR radar, multi-lateration,

  • and/or ADS−B and VHF voice communications are available. In this case the ADS-B must be via the 1090 Extended Squitter.

  • Airspace north of 80˚ North latitude. This Airspace is outside the reliable service area of geostationary satellites.

  • The New York Oceanic FIR

  • Tango routes. Aircraft not data link equipped are currently allowed to continue to operate on T9 and T213.

Performance Based Communication Systems, PBCS  Implementation

PBCS allows the oceanic controllers to reduce lateral and longitudinal separations while maintain the very low probability of mid-air collisions. PBCS is becoming part of your A056 LOA/OpsSpec. Simply stated, RCP is a measure of how fast the satellite links, pilots and ATC computers carry and respond to CPDLC messages. RSP is a similar measure of ADS-C. RCP-240 and RSP-180 are the desired performance levels. Operators requesting data link communications authorization must understand and comply with the guidance in AC 90-117 and their specific A056 authorization. When originally issued, A056 may not have included Required Communication Performance, RCP and Required Surveillance Performance, RSP information inside the approval. PBCS operational performance can be on the basis of an AFM statement , STC, fleet performance monitoring or individual monitoring performance. Operators who currently have an A056 authorization may choose not to upgrade to PBCS. These operators will still need to submit the specifics of their CPDCL/ADS-C install and operation and have the A056 re-issued with limitations of using PBCS. 
Reduced lateral separation minimum, RLatSM began 15DEC15. Only the Gander and Shanwick OCA’s have participated in the trial. Operators took note of this by the introduction of three core tracks in the NAT OTS separated by one-half degree, (25NM). RLatSM tracks are identified in “Remark 3” of the NAT Track Message. All flight operating on these tracks between FL350 and FL 390 are required to have operating RNP-4, CPDLC, ADS-C and TCAS/ACASII with system 7.0. If any of RLatSM required aircraft systems fail while operating in RLatSM airspace, ATC must be advised immediately so that an appropriate course of action can be determined. If the TCAS fails enroute to the NAT OTS, the aircraft may continue with RLatSM operations.
Phase 2 will expand the use of tracks that are spaced by one-half degree, beyond the core tracks to all of the NAT OTS tracks between FL 350 and FL 390 inclusive. RLatSM Phase 2 is expected to begin 4JAN18 and now has been delayed until 1FEB18.
The use of PBCS further reduces this separation to 23NM.  Similar Phase 1, after the 29MAR18 PBCS deadline, RLatSM trials will be replaced by 23NM lateral track spacing for operators specifically authorized for PBCS and Performance Based Navigation (PBN) separation criteria on three OTS tracks, between flight levels
350−390 inclusive. Theses tracks will be set aside for aircraft authorized for PBCS and PBN
With the introduction of half-degree spacing a whole new set of waypoints identifiers was introduced. Canada, the UK and Iceland strongly advocate that operators NOT use half−degree waypoint identifiers in the ARINC 424 format (e.g., N5250 = 52˚30’ NORTH 050˚00’WEST). The logic behind this is that some cockpit map displays result in truncation of waypoints comprised of latitude/longitude into a maximum of seven characters; minutes of latitude are not displayed. This means that FMC’s display would be the same if operating along whole or half degree waypoints. One way to mitigate this risk is through the use of 13-character display of the full latitude/longitude (e.g., N5230.0W050˚00.0) for the input of waypoint coordinates.  The FAA directs that if operators have a need to use the ARINC 424 5−character format waypoint identifier that an alternate format (e.g., H5250 = 52˚30’ NORTH 050˚00’ WEST. As a further risk mitigation, rerouting of flights onto RLatSM identified tracks containing ½ degree coordinates will only be permitted via CPDLC using Uplink Message UM79, UM80 or UM83. Aircraft will therefore not be rerouted onto ½ degree OTS tracks if ARINC 623 data link or voice is used for the issuance of the oceanic clearance.
Half-degree track spacing also affects the contingency selection used by pilots during Weather Deviation Procedures, Diversions or Turn-backs. Only when properly executed does the ICAO Doc #4444 Weather deviation procedure and In−flight Contingency Procedure provide separation from the adjacent traffic. When crossing adjacent tracks without an ATC clearance, the potential vertical separation provided may be as little as 300ft (Weather Deviation) or 500ft (Diversions or Turn-backs). These margins may not adequately account for RVSM Altimetry System Error.  Strong consideration should be given to intercepting the 15NM offset in the same direction of flight and then descending below FL 280 or climbing above FL 410 prior to crossing adjacent tracks or making a 180˚turn back.
The Strategic Lateral Offset Procedure, SLOP has been implemented as a standard operating procedure in the NAT Region since 2004. Calculations used in the RLatSM safety assessment demonstrate sufficiency to allow provisions for the application of SLOP up to 2 NM right of track or route centerline where the 25 NM lateral separation minimum is being applied. ICAO Document 4444 has been amended to allow additional SLOP offsets at 0.1 NM increments, as outlined in the excerpt below. However, at this time, 0.1 NM increments have not been adopted in any oceanic airspace. Only three options (Centerline, 1 NM right and 2 NM right)
remain available.

Reduced longitudinal Separation Trial, RLongSM

In 2012, Gander and Shanwick OCA’s implemented a trial of five-minute longitudinal separation minimum to be applied between eligible aircraft. This trial remains on-going. In November 2016 this trial expanded into Reykjavik CTA. The current Mach Number Technique, MNT same track longitudinal separation minimum in NAT HLA airspace is 10 minutes. The five-minute longitudinal separation minimum used in the trial becomes available the aircraft have entered the Gander, Shanwick or Reykjavik and the aircraft is equipped with FANS1/A (ADS-C and CPDLC) and has a data link connection is established with air traffic control. Flightcrews must adhere to the ATC assigned Mach number and report any failure or malfunction of their GPS, ADS-C, or CPDLC equipment to ATC as soon as it becomes apparent as the separation standard is dependent on aircraft equipment performance. SLOP and #4444 contingencies are unaffected. 

  1. 1. NAT HLA, Since 2015 LOA/OpsSpec B039+B036 have been issued based on RNP(RNAV)-10 or RNP-4 and the criteria found in AC 90-105. If your LOA/OpsSpec was issued before 2015, expect a “Tabletop” with the FAA and possibly a validation flight to have LOA/OpsSpec B039+B036 re-issued before 2020.
  3. 2. NAT DLM, With some exceptions, LOA/OpsSpec A056 is required to operate between FL350 and FL390 in the NAT. By 2020 this limit moves down to anything above FL290.
  5. 3. PBCS, By 29MAR18 A056 will need to be reissued containing PBCS information . No matter if RCP-240/RSP-180 has been achieved or not. Canada, the UK, Portugal and Iceland are all using the same deadline for PBCS. PBCS implementation in these airspaces will not be mandated however, reduced separation will only be applied between PBCS-qualified aircraft. Eligible aircraft identify themselves by the use of P2 and either J5 or J7 equipment codes in block #10A with a D1 in block #10B on the ICAO flight plan. PBCS also requires “SUR/180” and PBN/L1 in block#18.
  7. 4. RLatSM, This trail and implementation will have a large impact on the way you operate in the NAT OTS. This is driving the “Expand the Coordinates” piece in your oceanic SOP’s and making contingency procedures and more entailed process. Add in the PBCS piece and further reduction of the track separation is “Achieved”.
  9. 5. RLongSM, Application of this specific procedure by ATC will be transparent to flights that have received an altitude change clearance. Pilots simply have to request a change in altitude. Eligible aircraft benefit by having a greater opportunity to climb to more fuel-efficient levels, climb through or follow another eligible aircraft at the same level.