Time Based Separation: Bringing the Single European Sky one step closer to reality
21 July 2016 • Author(s): Andy Shand, General Manager of Customer Affairs at NATS
One year after NATS’ revolutionary Time Based Separation (TBS) arrivals system was implemented at London’s Heathrow Airport, Andy Shand, General Manager of Customer Affairs at NATS, reflects on the system’s track record and considers some air traffic management doors that are being nudged open by the new technology.
Since its introduction in March 2015 at Heathrow Airport, NATS’ TBS arrivals system has been saving time and money for all of the airlines using Europe’s busiest airport. Not only has TBS helped reduce delays for air travellers but it has also added resilience to a flight arrivals schedule that is full to bursting – the airport consistently operates at 98% capacity, facilitating more than 1,350 aircraft movements every day of the year.
NATS’ air traffic controllers have been using TBS for a full year for Heathrow approach. The system is in use at all times and its success is undeniable. More than 80% of aircraft landing at Heathrow Airport were able to safely land closer together than they would have using traditional distance-based separation. In strong wind conditions (headwinds of over 20 knots) NATS’ analysis shows that an equivalent of 180 nautical miles of separation space is typically saved between arrivals in a day. As an average in all wind conditions, approximately 78 miles are being saved per day and, when you consider that typical spacing between medium-sized aircraft is three miles, it becomes clear how that equates to recovering the landing rate. Crucially, there has been no increase in aircraft go-arounds or wake turbulence encounters under the TBS regime – and no adverse pilot enquiries or comments – and an overall reduction in flight cancellations.
As a whole, the airport is experiencing a more than 50% reduction in air traffic flow management wind delays and Heathrow controllers have been able to achieve an average of 1.2 more movements per hour across all wind conditions. In strong wind conditions this hourly rate increase rose dramatically to 2.9 more movements than was previously achievable using traditional distance based air traffic control separation methods.
In November 2015 alone NATS estimated that, despite winds of up to 60 knots on final approach, TBS saved 25,000 minutes of delay. In particular, on 10 November 2015, despite a 40 knot headwind, there were no flow regulations in place – a situation that would have been unthinkable under the old distance-based regime…