GPS RAIM Prediction Service

DWI is pleased to offer its generic GPS RAIM Prediction Service (GRPS) to the aviation community. The GRPS can deliver RAIM prediction data for airports, en-route, terminal area and approach phases of flight.

The GRPS consists of a central calculation unit which is a fully parameterized core RAIM calculation engine. Around this core engine is built the interface to our partners. DWI are completely flexible on the interface and can customize it to match the requirements of an individual partner. This means that the GRPS service could be fully integrated into a partner's system (e.g. flight planning systems) or provided as a standalone service (e.g. regular AFTN/e-mail message updates).

A RAIM request from the partner interface to the GRPS core engine may encompass multiple NPA requests and/or multiple Route requests.

NPA Request

The following parameters are used:

• Result format: Graphic/Text/Both
• Aerodrome location: ICAO Identifier (requires database lookup), or explicit Latitude (decimal degrees/Deg.Min.Sec.), Longitude (decimal degrees/Deg.Min.Sec.) & Elevation (feet/metres)
• Scenario information: Scenario start date & time and either a scenario end date & time or a scenario duration
• Algorithm: FD/FDE (Fault Detection/Fault Detection Exclusion)
• Barometer-Aiding: Non-Baro only, Baro only, or Non-Baro and Baro
• Mask angle (degrees/radians)
• Minimum Outage Duration (mins/secs) - outages that are less than this will NOT be reported
• Sample Period (mins/secs) - interval at which to generate RAIM samples during the scenario

Calculates RAIM availability at a required aerodrome specified point [ARP] using 1 minute sample period for the requested scenario time period [start end].

Route Request

The following parameters are used:

• Result format: Graphic/Text/Both
• Scenario information: Start date & time
• Algorithm: FD/FDE (Fault Detection/Fault Detection Exclusion)
• Mask angle (degrees/radians)
• Minimum Outage Duration (mins/secs) - outages that are less than this will NOT be reported
• Sample Period (mins/secs) - interval at which to generate RAIM samples during the scenario
• Set of waypoints. For each waypoint:
• Name/Identifier
• Latitude (decimal degrees/Deg.Min.Sec.), Longitude (decimal degrees/Deg.Min.Sec.) & Elevation (feet/metres)
• Waypoint time - can be explicit point-in-time or a number of mins/sec from a the previous waypoint or start of the scenario

Calculates RAIM availability along the route specified by waypoints with an assumed point-to-point path. Intermediate points are calculated to maintain a 1 minute time elapsed spacing between calculation points assuming constant speed. The route model [waypoints, intermediates and relative arrival times] is run for start times +/- 15, 10, 5 minutes and on time given an on-time start time.

Reliability, Accuracy, Integrity

GRPS is able to include short-notice and planned outage information as it uses the latest constellation almanacs and NANUs supplied by the US Coastguard to calculate the RAIM prediction. All calculations are performed real time and not on a precalculated grid.

All GRPS solutions will meet the regulatory requirements required for a particular partner. DWI work closely worldwide with operators and regulatory bodies to continually ensure the compliance of all GRPS solutions.

A GRPS solution is scaleable to support the requirements of smaller regional airlines and major international operators alike. DW provide full automation and redundancy to ensure reliable service delivery. Current GRPS clients include Air France and Jeppesen.

GRPS can be combined with DWI's GPS Monitoring System service to give a local and Wide-area RAIM monitoring and prediction service.

For more information about GRPS please call John Wilde on +44 (0) 118 324 0172 or email us at info@dwint.com.