The Honeywell/Pelorus SLS-2000differential global-positioning-system (GPS) satellite landing system now has US Federal Aviation Administration Special Category 1 (SCAT-1) approval.

The "fail-operational" SLS installation comprises three GPS "pseudolyte" Remote Satellite Measurement Units (RSMU) up to 100m from an SLS ground reference station. The RSMUs supply the station with a position from the GPS satellites, and as the station knows the exact RMSU positions it calculates the local GPS "differential" positional error.

This error correction is sent via datalink to approaching aircraft, so that on-board navigation computers can correct the aircraft's own GPS-derived position and construct and follow a more accurate approach path. The system can be used for any approach lying within a 55km (30nm) radius of the ground station, and promises to replace the traditional instrument landing system (ILS) as the primary means of terminal area navigation.

Honeywell's SLS-2000 business development manager, Jay Mesiti, says an SLS-2000 would typically cost "less than $300,000", or around one-third the cost of just one ILS installation.

Advantages over ILS include curved approach capability and missed approach guidance. Pelorus claims the system enhances runway availability and safety, allowing Cat 1 precision approach and landing. It can be upgraded to Cat 3 minima.

Mesiti says that commissioning of the system at both Minneapolis/St Paul and Newark International Airports will occur in late 1997, which will be achieved utilising a Boeing MD-80 operated by Continental Airlines.

Source: Flight International