System Offers Higher Degree Of Accuracy Than GPS
Successful trials have recently been conducted at Lausanne,
Switzerland, using the European Geostationary Navigation Overlay
Service (EGNOS) to guide a helicopter as it approached and touched
down at an emergency medical service landing pad.
The adaptable, go-anywhere characteristics of helicopters make
them ideal for emergency services, but when visibility is poor
their operations are limited by aviation regulations. The accurate
position reporting and navigation system integrity checking offered
by EGNOS will be a vital service for anywhere, anytime rescue
services.
The trials were performed by Eurocopter, using its EC155
experimental all-weather helicopter (type shown below). The trial
was coordinated by skyguide, the Swiss air navigation service
provider, and consisted of a number of validating approaches
performed by the HTT to a Helicopter Emergency Medical Services
(HEMS) pad located on the roof of Lausanne University Hospital,
according to the European Space Agency.
The test team was hosted in Lausanne's La Blécherette
aerodrome by the Swiss medical air rescue agency Schweizerische
Rettungsflugwacht - Garde Aérienne Suisse de Sauvetage -
REGA who also participated in the flight tests.
The trial approaches were designed by skyguide for 6 degree and
9 degree approach angles. Initial feedback from the test pilots
indicates that, despite of the steepness of the approaches - the
standard approach angle is 3 degrees - they are easy to fly because
of EGNOS' three-dimensional guidance. Vertical guidance for the
pilot is a major advantage EGNOS offers over standard GPS.
The increased approach angles also reduce noise nuisance on the
ground as the helicopter can remain at high altitude until it is
closer to its destination before commencing its final descent. In
addition, a steeper descent angle reduces the noise generated by
the rotor blades as the craft nears the ground.
The implementation of instrument approaches for HEMS operations
will allow the emergency services to continue their operations in
weather conditions that would otherwise ground their helicopters,
said the ESA.
The trials were performed as part of the GNSS Introduction in
the AviatioN secTor (GIANT) project. GIANT is a European Commission
Sixth Framework Program (FP6) project with the aim of supporting
the introduction of EGNOS and Galileo services into the aviation
market while demonstrating to the responsible authorities that the
required safety levels are achieved.
The helicopter trials follow on from the fixed-wing EGNOS/GIANT
trials held at Valencia, in Spain, during late 2006. Additional
GIANT flight trials will be performed in 2007 at other European
airports and on an oil rig in the North Sea.
EGNOS is a joint program of the European Space Agency, the
European Commission and Eurocontrol. EGNOS is made up of a network
of more than 40 elements all over Europe that collect, record,
correct and improve data from the US Global Positioning System
(GPS).
The modified signals are then relayed via geostationary
satellites to user's terminals, offering a positional accuracy of
better than six and a half feet, compared with 50 to 65 feet for
GPS alone. In addition, EGNOS gives a guarantee of quality for
these signals that GPS does not provide.
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