The EGNOS trial using the HTT was performed under a Eurocopter contract with the European Space Agency and involved checking the experimental receiver on the EC155. Whatever the aircraft attitude - whether in a turn or nose-up - the satellite signals were continuously received and correctly decoded. The results confirmed that EGNOS met its accuracy objectives: ±2m horizontally and ±3m vertically.
Test flights, performed over the rugged Alpilles and Mont Ventoux landscapes of southern France, demonstrated that the EGNOS signal could be clearly received even during flight below north-facing contours or within steep valleys. In the second phase, the receiver will be linked to the helicopter's flight management system, replacing the flightpath guidance provided by GPS or DGPS. This will allow the crew to perform approaches in full automatic mode on steep glideslopes (from 6-15°) under EGNOS guidance, followed by automatic transition to the hover.
Eurocopter claims that using EGNOS for approach guidance in full automatic mode will be a world first. The results will pave the way for the development of specific IFR approach and navigation procedures for helicopters, enlarging the operating envelopes of rotorcraft in poor weather conditions.
Source: Flight International
