"November 2015 was a windy month with 15 days when there were strong headwinds; the worst was November 15th when we had headwinds of 60 knots straight down the runway," says Andy Shand, General Manager Customer Affairs at NATS. "We estimated that we saved over 25,000 minutes of delay in November alone." TBS has on average enabled 20 extra landing aircraft per day over distance based separation at Heathrow. When the headwinds have been more than 20 knots this goes up to 49 extra landing aircraft per day.
Detailed measurements of wake turbulence at Heathrow between 2008 and 2013 using Light Detection and Ranging (LIDAR) laser-ranging equipment loaned by EUROCONTROL to measure 150,000 aircraft tracks from two different glideslope locations as part of the Single European Sky ATM Research (SESAR) programme, showed that as the wind speed increases the wake decays more rapidly.
TBS went from initial trials in January 2015 to operational mode in March 2015 after which it has been in almost continuous use at Heathrow. "TBS has brought real benefit to our customers through reducing delays in high winds," said Andy Lord, British Airways Director of Operations. Such is the potential for TBS to improve resilience at busy airports it has been adopted as a Pilot Common Project, a SESAR project which has been mandated by the European Commission for deployment at the continent's busiest hubs.
"Time based separation addresses the biggest single cause of arrival delay at the airport. Heathrow has been operating at 98% capacity for over a decade so technology like this is essential providing the best service possible to our passengers," says Derek Provan, Operational Strategy Director at Heathrow Airport Limited.
Accurate and real-time information on wind is obtained from aircraft Mode-S transmissions – but could also be obtained from alternative sources such as automatic dependent surveillance – broadcast (ADS-B) or LIDAR – and, as the tool is modular, new data sources can be added at any stage. The safety regulator was incorporated into the research programme at an early stage so the safety case could be developed and approved. The Intelligent Approach suite of tools is modular and portable enabling it to work with existing systems to provide controllers with clear separation parameters which they can apply to aircraft on approach.