NAT HLA Changes 28MAR19

A New Acronym for Your Vocabulary

On  28 March 2019, Shanwick, Gander and Santa Maria Oceanic Control Areas will commence a trial implementation reduced longitudinal (Nose-to-Tail) separation. This reduced separation can be as little as 14NM for aircraft operating on same track or intersecting tracks. This new procedure is called, Advanced Surveillance-Enhanced Procedural Separation, ASEPS. If operating on an opposite-direction reciprocal track, aircraft may be cleared to climb or descend to or through the levels occupied by another aircraft provided that the aircraft have reported by ADS-B having passed each other by 5 NM. The trial will run until November 2020. It is anticipated that the amendments will become effective on 5 November 2020. You might have guessed by now that this new separation standard is based on ADS-B. This difference here is that ADS-B for this purpose will be spaced based vice ground based receivers. Space-based (SB) ADS-B will permit uninterrupted ATS surveillance for equipped aircraft before, during and after entry into the North Atlantic (NAT) Region. The space-based ADS-B system will consist of a constellation of LEO satellites hosting ADS-B receivers. A satellite will receive ADS-B data including position, velocity and altitude from aircraft, which is then routed through other satellites and down-linked to a satellite operations ground station from where it is on-forwarded to Shanwick and Gander. Santa Maria will utilize the existing ground based ADS-B system. Operators do not have to apply to be part of the trial. As long as they meet the qualifications below, they will be participants in the trial. This trail will be based upon aircraft that are capable of:

  • RNP-4
  • RVSM
  • HLA approval
  • ADS-B, with dedicated 1090 Mhz out capability
  • Aircraft meeting the specifications of RCP 240 and RSP 180



Flight plan equipment codes that function for the requirements listed above are:

  • “J5” to indicate CPDLC FANS1/A SATCOM (Inmarsat) data link equipment
  • “J7” to indicate CPDLC FANS1/A SATCOM (Iridium) data link equipment
  • “P2” to indicate RCP 240 approval;
  •  “D1” to indicate ADS-C with FANS1/A
  • “B1” or “B2” to indicate ADS-B.
  • “PBN/” followed by “L1” for RNP4 and “SUR/RSP180”

More Changes and Other Stuff that Remains the Same

There are significant revisions to the current ICAO Doc 4444 Contingency Procedures. General oceanic contingency along a revised weather deviation procedures will be included in a revised version of NAT Doc 007 Operations and Airspace Manual for the duration of the trial and until such time as they are published in ICAO Doc 4444. 

The offset distance used inside the General Oceanic contingency and Weather Deviation contingency have reduced the distance to 9.3km/5NM. The 500ft altitude split (in RVSM) for General Oceanic remains the same as does the 300ft offset for the
Weather Deviation procedure. The NAT planners have restated a strong recommendation for pilots to consider a descent below the predominant flow of traffic in a parallel track system where the aircraft’s diversion path will likely cross adjacent tracks or routes. A descent below FL 290 can decrease the likelihood of: conflict with other aircraft, ACAS RA events and delays in obtaining a revised ATC clearance.

The Strategic Lateral Offset Procedures, SLOP implemented as a standard operating procedure in the NAT Region since 2004 (non-micro SLOP) remain unchanged.

There is a really helpful graphic on page #4 in NAT OPS Bulletin 2018 -005, “Special Procedures For In-Flight Contingencies”

Here is the link to download NAT OPS Bulletin 2018 -005 and NAT OPS Bulletin 2018 -006.

A New Rule Book for the North Atlantic

A new NAT Document #007 has been issued. Version 2019-1 was released on 18DEC18 and takes effect on 29MAR19. Changes to the Performance Based Communication and Surveillance,PBCS implementation and the conclusion of the RLatSM trial. This means that the new title for “RLatSM tracks” is now “PBCS tracks”. There are now guidelines on the application of user-preferred trajectories in Chapter 4 Flight Planning and Chapter 6 Communications and Position Reporting Procedures. For you Pacific flyers this will be a familiar procedure. Like we described above, contingency procedures replacing the current ones are detailed in Chapter 13, “Special Procedures For In-Flight Contingencies”. It is important to keep in mind that these new procedures are applicable in the NAT Region from 28 March 2019. A sharp eye will also see that the new General Oceanic and Weather Deviation procedures are being implemented with the trial of Advanced Surveillance-Enhanced Procedural Separation, ASEPS in the Shanwick, Gander and Santa Maria Oceanic Control Areas, and subsequently replace those currently published in the PANS-ATM/ICAO Doc 4444 for the Nat Region only. Take a look inside Chapter 6 and you will find the       answer on how to use proper HF phraseology procedures when in a FANS compliant aircraft. Of course there are numerous editorial and organizational changes for clarity and consistency. Modifications have been made to the Glossary of Terms: new information has been added and unnecessary information has been removed; as well, the structure has been changed to divide into “Abbreviations” and “Definitions”. Here is a link to the new NAT Doc#007 download