by Aimee Turner in Geneva
New form of continuous descent approach technique could help lower noise and emissions at congested airports
Eurocontrol is formulating a hybrid continuous descent approach (CDA) technique combining precision area navigation (P-RNav) with a flexible air traffic control (ATC)-directed system to help airports reduce aircraft noise and emissions at peak times.
The European air navigation organisation is ready to develop advanced CDA techniques following promising early trials, said Eurocontrol director general Victor Aguado at last week’s Aviation and Environment Summit in Geneva, Switzerland.
CDAs are designed to enable pilots to descend from cruising altitude on idle power until they intercept the glideslope for final approach, minimising fuel consumption and potentially halving the amount of acoustic energy that reaches the ground.
Eurocontrol airport sustainability expert Alan Melrose said there have been around 14 CDA initiatives, some using P-RNav for standard terminal arrival routes (STAR) and others verbal “distance to go” instructions from ATC, which give pilots the ability to optimise their flight paths.
“What Eurocontrol is planning now is to harmonise phraseology, training and written procedures to allow European airports to opt for either or both CDA techniques,” said Melrose. “Airport choice will often be determined by airspace design and traffic volumes.”
Eurocontrol is also developing controller support tools to introduce an element of automation to the pure radar CDA variant as part of its TMA 2010+ project.
Trials have been conducted at three airports. Manchester in the UK night-tested a radar-based CDA technique using BA Connect and BMIbaby aircraft. This included an assessment on a Boeing 737-300 from an altitude of 5,000-6,000ft (1,520-1,850m). Manchester aims to use both CDA techniques comprehensively within two years.
Bucharest tested CDA from 12,000ft and aims to increase this altitude. It assessed 737s and ATR turboprops operated by Romanian flag carrier Tarom using P-RNav, and plans to introduce the verbal variant for all arrivals.
Stockholm, working on a more detailed dual-variant programme with Scandinavian Airlines, launched P-RNav trials in January and plans to introduce the verbal variant later this year. Eurocontrol plans to use the results of this trial to produce a “best practice” case study.
“A key message is that the benefits of CDA can be optimised by incorporating low power, low drag techniques – which essentially means determining optimal deployment of the undercarriage so you fly the aircraft as cleanly and as quickly as possible. Everything hinges on energy management of the aircraft,” said Dick Smith, Eurocontrol’s CDA technical consultant.
Smith said the perception that CDAs can reduce airport capacity during busy periods and are best suited to night flights is about to be challenged, but that it will require a multi-agency approach.
“CDA can be used on any powered aircraft at almost any airport in almost any traffic conditions. It only requires a change of mindset within the pilot community,” he said.
Source: Flight International
