RLatSM connection issues delay NAT rollout

RLATSM storyConnectivity issues are thwarting the next phase of the innovative RLatSM trials conducted by the UK’s NATS and Nav Canada.

Most aircraft transiting the North Atlantic (NAT) are separated laterally by one degree of latitude, approximately 60 nm, on tracks that are set daily based on the traffic demand and prevailing weather conditions, such as the jet stream.

RLatSM or Reduced Lateral Separation Minima were introduced as part of a trial in December 2015. RLatSM involves the addition of a new track in the core of the NAT tracks that is separated laterally by a half a degree of latitude, or approximately 25 nm from the neighbouring tracks thanks to advances in aircraft and air traffic management technologies.

This allows more aircraft to achieve their optimum route and flight level, helping to cut flying times and reduce fuel burn and emissions. NATS tells Air Traffic Management that the first phase of a trial to introduce reduced lateral separation between aircraft flying over the North Atlantic is currently meeting its success criteria and is used daily within the Shanwick and Gander Oceanic Areas.

Between December 2015 and September 2016, over 43,000 flights took advantage of the change, allowing them to take the most efficient route over the ocean. This equates to just over a quarter of all transatlantic traffic operating within the established track structures during the defined track periods, with their use steadily growing throughout.

It now emerges that the plan to expand the RLatSM area – progressing to Phase 2 of the trial which would see it extending throughout the entire North Atlantic Organised Track System – has been put back and will not launch from the November 2016 date as originally intended.

NATS reports that within the Shanwick and Gander Oceanic Control Areas, analysis of CPDLC (Controller Pilot Data-Link Communication) and ADS-C (Automatic Dependant Surveillance – Contract) connectivity has shown a number of transaction issues on a daily basis resulting in an increase in controller workload.

Datalink allows controllers to communicate and pass instructions to pilots electronically and is a requirement for aircraft flying on these reduced separation tracks so whenever connectivity ‘drops’, controller workload increases to resolve the situation.

“Once a satisfactory number of fixes that mitigate controller workload have been identified and introduced, and the achievement of robust safety assessment criteria met, Shanwick and Gander operations will progress to Phase 2 of the trial, however until then both operations will continue within Phase 1,” confirms NATS.

The latest issue of Air Traffic Management is out. Read it on the free ATM app here.

The latest issue of Air Traffic Management is out. Read it here using the free ATM app.

“The connectivity issues have multiple causes, therefore NATS and Nav Canada are working closely with all stakeholders to identify areas for improvements. It absolutely remains our intention to transition into Phase 2 and we will continue to keep our airline customers informed as the situation develops.”

Each full year of RLatSM operation is expected to generate an annual reduction of greenhouse gas emission totalling over 10,000 tonnes. In Nav Canada’s latest Collaborative Initiatives for Emissions Reductions (CIFER) progress report on its efforts to reduce its environmental footprint, the total achievable customer benefits of RLatSM up until 2020 is pegged at reducing carbon dioxide emissions by 35,000 tonnes.

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