If airlines could make departures and approaches shorter, less time-consuming, and more fuel-efficient, they would save money. If the secondary effect of adopting procedures to achieve these objective could cause less local noise nuisance and lower emissions, that would increase the incentive.

But at most airports airlines know they will have to work with existing infrastructure to achieve this.

Under the project name Vinga, a group of companies and organisations with a green vision have integrated traditional and state-of-the-art navigation systems to produce the desired result. At Gothenburg's Landvetter airport in southwestern Sweden, the Vinga team have integrated satellite-guided required navigation performance (RNP) departure and arrival procedures seamlessly with the instrument landing system precision approach.

This combination allows airlines to harness the flexibility of RNP for departures and let-downs with the integrity and precision of the venerable land-based system for the final approach and landing. And on 7 April, in a world first, a Novair Airbus A321 carried out a seamless RNP letdown to the ILS at Landvetter. As Sweden's air navigation service provider LFV says: "This is a major breakthrough, demonstrating that green approaches can now be carried out independent of weather conditions."

Vinga is the name of an island just off Gothenburg, and is Sweden's most westerly territory.

But although this marriage of RNP with ILS is a happy one, it was by no means the sole Vinga objective. The project is an exercise in minimising all emissions and noise nuisance, whether on the ground or in the air, and it is backed by the Single European Sky research project SESAR. The Swedish Transport Agency is responsible for regulation of the airborne procedure, which is categorised by the International Civil Aviation Organisation as RNP-AR (required navigation performance - authorisation required).

Landvetter was chosen as the base because it has plenty of traffic, but not so much as to make trials impossible, and both the infrastructure providers - the airport operator Swedair and LFV - were keen to participate.

LFV could see that, if it could validate this integration of traditional with modern guidance for approaches and departures, there are many more airfields in Sweden that could ultimately benefit from the developed techniques.

The remaining components needed for the Vinga trial were a carrier and an expert in all the sciences surrounding RNP procedures, avionics and approach design. Novair, a Swedish carrier owned by the Kuoni travel group, became the airline partner, and Airbus subsidiary Quovadis, a specialist performance-based navigation systems designer, completed the equation by bringing its expertise to the party.

Airbus itself defines its role as being "the aircraft air traffic management architect", bringing together all the airborne technologies and crew interface to create the aircraft's capability to fly the new procedures. The manufacturer points out that it has long been committed to making its aircraft fully 4D-navigation capable.

In 4D navigation, the fourth dimension is time, and the purpose is that the aircraft's trajectory is managed so that when the aircraft reaches any point in the journey, on the ground or in the air, the system is expecting it, and is ready for it.

Sweden has been working for many years to apply ecologically sound operating techniques to aviation, and it is continually looking more ways of achieving sustainability.

Last year LFV introduced direct routeing throughout Swedish airspace above 26,000ft (8,500m). Swedavia, which operates 11 Swedish airports, has reduced its carbon dioxide emissions by 60% since 2003, and Landvetter itself was accredited "climate neutral" for its on-airport operations in 2010.

Swedavia has joined the Vinga project to play its part via the SESAR-promoted system-wide information management (Swim) network with LFV and the carriers to act together to enable ideal airborne 4D trajectories, and zero delay on the ground.

Flightglobal was invited to take part in a short Vinga demonstration flight in a Novair A321 with all the stakeholders present to celebrate the successful validation of all the procedures. The flight was brief, demonstrating a green departure and climb to cruise, then a similarly green arrival. It began with Landvetter tower clearing the flight to push back when it was clear there would be no delay for taxi or line-up/take-off.

Taxi out, captained by Andreas Linner with Johann Naslund in the right-hand seat, was single engine until about a minute before arrival at the runway. There was no delay for line-up or for starting the take-off run, which was carried out with a reduced-flap configuration to gain an aerodynamically cleaner early climb.

Acceleration to best climb speed was achieved quickly while the flight management system followed an RNP departure that avoided communities on the ground as well as meeting terrain constraints.

On return to Landvetter, from cruise the aircraft carried out a continuous descent at idle power following an RNP pattern which, like the departure, avoided both terrain and communities, and cut corners where permitted compared with the conventional approach, delivering the aircraft to a seamless ILS intercept at about 5nm from the runway.

Quovadis' Paul-Franck Bijou points out that getting a barometric VNAV descent to intercept perfectly with the geometric descent profile presented by the ILS was, technically, the most difficult challenge for his company and Airbus. Essentially, however, it only takes is a software upgrade to the flight management system. The airlines will be delighted to learn that no additional hardware is involved.

On touchdown, carried out with less than full flap, the crew engaged idle reverse and, when off the runway, shut down one of the engines for taxiing. There was no delay during taxiing, nor any waiting for the stand. The latter may not sound particularly impressive, but it is important considering how many airports make aircraft wait for a stand, with engines running, some of them for a long time.

Airbus estimates a carbon dioxide saving of 1t per airport visit when Vinga RNP procedures are followed, and of course noise is also reduced. Novair's operational flights at Landvetter will use the new procedure for more than 100 flights before September this year during which measurements will be taken to validate the procedure.

Source: Flight Daily News