German carrier Air Berlin has secured approval to conduct Category I satellite-based approaches following trials which the airline began last year.

Air Berlin has been taking delivery of Boeing 737-700s and -800s since mid-2007 with the GPS-based landing system (GLS). The carrier says it will have 10 by the end of this year and will receive 80 GLS-capable aircraft in the next five years.

GLS approaches, which use satellite-based positioning augmented by a local ground station, are an alternative to those conducted with regular instrument landing systems.

While ILS limits aircraft to straight-line approaches, GLS allows for curved paths which can be shorter and more flexible, and reduce ground noise.

"In future the airline will be able to use it for normal flight operations," says Air Berlin, adding that GLS offers "considerable cost-saving potential".

Air Berlin 737-700
 © Air Berlin

Air Berlin has been conducting test flights at Bremen, following clearance from German regulator LBA in August last year, and has also performed evaluations at Malaga in Spain.

Cockpit procedures for Bremen involved the flying pilot initially setting the GLS channel while the non-flying pilot set the ILS frequency - or used runway approach lights in visual conditions - to crosscheck the GLS signal.

During the Bremen tests the decision height was fixed at 440ft, with runway visual range at 650m, but the approval for normal operations enables these precautionary minima to be reduced to 200ft and 550m, the full criteria for Category I approaches.

Testing at Malaga involved a prototype ground station, which meant that the GLS signal was used for monitoring only. The flying pilot set and flew the ILS but the non-flying pilot set and observed the GLS channel.

Under normal operations GLS procedures, such as autopilot mode selection and annunciations, are identical to those for ILS, requiring no additional pilot training.

Air Berlin's chief for the Boeing fleet, Marc Altenscheidt, says that the GLS approaches have been shown to be more precise than those using ILS.

"Our tests with satellite-based approaches were so successful that we are convinced that GLS is the technology of the future for global air traffic," he says.

But he adds that GLS will have to be approved for the stricter Category III approach criteria in order to replace fully the ILS infrastructure in Europe.

Source: Air Transport Intelligence news