Change & Compliance

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Avfuel’s Avplan Trip Support division explains the latest North Atlantic Regulations, designed to enable more efficient use of busy airspace

Within its support effort for business and VIP aviation customers, Avfuel’s Avplan Trip Support division is drawing attention to significant rule changes contained in the 2018-001 North Atlantic (NAT) Operations Bulletin, highlighting what flight operations departments need to know to ensure safe, compliant flight planning in the future. The rule changes concern new separation minima for optimised flying in the North Atlantic Organised Track System (OTS) and come into force on 29 March 2018.

NAT High Level Airspace (HLA) is being modified to safely accommodate more aircraft in tighter airspace, a process that requires additional avionics capability, and the 2018-001 update is the next step towards establishing the new standard. Prior to 29 March, the OTS operated as a hybrid of the old spacing system and the incoming system, aircraft flying on standard tracks with one degree of lateral separation and 10 minutes of longitudinal separation, or on reduced lateral separation minima (RLatSM) tracks, separating them by a half degree laterally and five minutes longitudinally.

Diagram 1 (upper right) shows standard flight tracks in green and RLatSM tracks in red. The RLatSM were only available at FL350-390 and represented optimised routes. For them to accommodate more traffic, their spacing needs to be reduced, requiring aircraft to have improved communications and surveillance equipment, which for some will mean updated or additional avionics.

The Change & Compliance
From 29 March, new rules, known as Performance Based Communication and Surveillance (PBCS) will manage the NAT HLA OTS. The PBCS system combines and eliminates the use of two older terms, reduced lateral separation (RLat) and reduced longitudinal separation (RLong). The NAT HLA OTS PBCS spacing – which still occurs at FL350-390 – is defined as 23nm of lateral separation and five minutes of longitudinal separation, with 20nm of latitude separation and 50nm of longitudinal separation for New York Oceanic and Santa Maria Oceanic traffic. The existing half-degree latitude separation tracks will become PBCS tracks.

Since PBCS tracks will be closer together than standard tracks, the NAT OTS will publish more of them, gradually phasing them into use through October 2018; flight operators can expect a majority of tracks to be PBCS standard and by October 2018 all tracks in the NAT OTS are expected to be PBCS.

Using a PBCS track will require either a half degree or full degree of lateral separation; either way, the same requirements apply and aircraft will need PBCS-compliant avionics. These will need to match required navigation performance 4 (RNP4), be controller-pilot data link communication (CPDLC) capable of required communication performance 240 (RCP240), and automatic dependent surveillance-contract (ADS-C) capable of required surveillance performance 180 (RSP180). Operators should be careful to note that aircraft equipped with CPDLC and ADS-C are not necessarily capable of RCP240 and RSP180, respectively.

Avplan’s account manager, David Kang (left) confirms: “Long-range aircraft built after 2014 usually have RNP4, CPDLC and ADS-C installed out of the factory, but some shorter-range aircraft may not.” For now, the new regulations don’t exclude non-equipped aircraft from the North Atlantic. “Initially, the new regulations are only for the organised track space. Random/free routing aircraft are not affected unless they cross the tracks, when the special rules take effect.”

For some operators, complying with PBCS requirements means absorbing additional costs and finding time for installation. “It requires more than a simple firmware update,” Kang says. “Also, with the ADS-B standard less than two years away, upgrades should be done with ADS-B in mind. By 2020, all aircraft in NAT HLA will need to comply with new standards, eventually encompassing the entire NAT HLA from FL290 and above.”

In order to show PBCS compliance, US operators may need to update their Letter of Authorization or Ops Specs for Data Link Communication A056, and flight operators will need to update their ICAO flight plan output with the correct codes in order to show the proper equipage for track-clearance eligibility.

Aircraft going ‘against the grain’ may cross through PBCS airspace vertically and laterally in limited situations. For instance, an aircraft may be able to laterally cross one waypoint per track, but not join the flow, as shown in Diagram 2 (lower left). In addition, climbing or descending through tracks might be possible, but it must be continuous and not a step climb or descent. Any PBCS track infringement will be left to the Oceanic Center’s discretion.

“Tighter air space means tougher regulations for obvious safety reasons,” says Kang. “As avionics evolve, it makes sense for flight tracks to evolve in line with their capabilities. It simply means that those aircraft not up to speed with the avionics requirements will be unable to benefit from the heightened flight track efficiency because they won’t be able to do so safely. Think of it like this: You might want to fit more vehicles on the same expressway, but the road itself must remain the same size. The only way to do it is to narrow the lanes, decreasing the space between cars. But to drive safely in lanes half as wide, the drivers need better technology. Would the result be efficient? Most definitely. But only those vehicles capable of making the journey safely would be able to use the road.”

Perhaps most significantly of all, Kang notes: “Many other countries, including Australia, have already implemented ADS-B requirements and use it as the primary method for control – these new regulations are connected with the US ADS-B rollout, part of the greater NextGen modernisation effort. In 2020 we’ll reach a significant milestone, when the US and Europe synchronise their airspace requirements and begin the next phase of the modernisation process.”