This summer a Eurocopter EC 155 all-weather demonstrator performed satellite-guided precision approach tests in Lausanne, Switzerland, as part of a research program aimed at developing approach and departure IFR procedures suited to helicopters using the European geostationary navigation overlay service (egnos) Skyguide, the Swiss air navigation service provider, coordinated the program. Swiss medical air rescue agency Rega was also involved. Additional flight trials are to be performed this year at other European airports and from an oil rig in the North Sea.

The main benefit of egnos over the standard GPS is its vertical guidance capability. egnos, a ground-based augmentation system of the GPS, is the equivalent of the U.S. WAAS. It is not in service yet.

Trial approaches were designed for six- degree and nine-degree angles. The European Space Agency (ESA) reported that the test pilots provided positive feedback. “Despite the steepness of the approaches–the standard approach angle is three degrees–they are easy to fly, thanks to the three-dimensional guidance provided by egnos,” the agency stated.

The increased approach angles reduce noise nuisance on the ground since the helicopter can remain at high altitude until it is closer to its destination before beginning its final descent. In addition, a steeper descent angle reduces the noise generated by the rotor as the aircraft nears the ground.

The implementation of instrument approaches in Europe for helicopter emergency medical service operations will allow air rescue and ambulance operators to continue flying in weather conditions that ground their helicopters today, the ESA said.