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DW International
Bespoke Solutions for Aviation

GNSS RAIM/RNP Prediction Service

RAIM Prediction – Automatic and Direct

The GNSS RAIM/RNP Prediction Service – GRPS – has been developed to meet the demanding requirements of the RNAV community in its efforts to meet PBN guidelines and State requirements. A versatile and flexible service, GRPS has been adopted by many operators, flight planning service providers and ANSPs where it has been seamlessly integrated into their existing systems and operations.

How it Works

GRPS supplies real-time RAIM predictions and RNP predictions direct to end users through their existing flight-planning suites. It is fully automated so that flight planners obtain the RAIM prediction as they plan the route. The service allows flight planners, dispatchers and aircrew to plan around periods of reduced GNSS availability by taking all route details from the flight plan and calculating RAIM availability for all route types – oceanic, en-route, terminal, and approach – on a leg-by-leg basis, including destination and alternate airports for RNAV and RNP operations anywhere in the world.

Future-proof Capabilities

GRPS allows operators to comply with all FAA, European, ICAO and other worldwide RAIM prediction requirements and guidelines. GRPS covers all PBN applications, from RNAV 10 and RNP 4 to RNP AR APCH (down to RNP 0.1). In the future GRPS will provide RAIM predictions for new constellations – Galileo, GLONASS and COMPASS.

GRPS Applications

GRPS generates RAIM predictions and RNP predictions for all international and PBN applications including:
  • MNPS • RNAV 10 (also known as RNP 10) • RNAV5 (B-RNAV) • RNAV 2 (previously US RNAV Type A) • RNAV 1 (P-RNAV and previously US RNAV Type B)
  • RNP 4 • RNP 2 (Standard in development)
  • Basic RNP 1 • Advanced RNP (Standard in development)
  • RNP Approach LNAV/VNAV and LP/LPV (Standard in development) • RNP AR Approach (US SAAAR)
As new standards are finalised, the GRPS will be updated to accommodate them.

Reliability, Accuracy, Integrity

GRPS is able to include planned and short-notice 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 in real time and not on a pre-calculated grid.

DWI works closely worldwide with operators and regulatory bodies to continually ensure the compliance of all GRPS solutions with local requirements and international guidance.

The GRPS solution is scaleable to support the requirements of smaller regional airlines and major international operators alike. DWI provides full automation and redundancy to ensure reliable service delivery. 

Architecture

The GRPS consists of a central calculation unit which is a fully parameterized core RAIM calculation engine. DWI then customize the interface to the client system to meet 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 Aerodrome requests and/or multiple Route requests. Both solutions are on-demand providing users with an instant response.

Aerodrome Request

The following parameters are used:
  • Aerodrome location: 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)
  • Selective Availability: On/Off
  • Barometer-Aiding: Non-Baro only, Baro only, or Non-Baro and Baro
  • Receiver Equipment: C129/C145
  • Mask angle (degrees)
  • Minimum Outage Duration (mins/secs) – outages that are less than this are not reported
  • Sample Period (mins/secs) – interval at which RAIM samples are generated during a scenario
  • RNP – RNP Value being flown
  • Result Format: Graphic/Text/Both
The service 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:
  • Scenario information: Start date & time
  • Algorithm: FD/FDE (Fault Detection/Fault Detection Exclusion)
  • Selective Availability: On/Off
  • Barometer-Aiding: Non-Baro only, Baro only, or Non-Baro and Baro
  • Receiver Equipment: C129/C145
  • Mask angle (degrees)
  • Minimum Outage Duration (mins/secs) – outages that are less than this are not reported
  • Sample Period (mins/secs) – interval at which RAIM samples are generated 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
    • RNP – RNP Value being flown for each route segment
  • Result format: Graphic/Text/Both

The service 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

Terrain Screening

Terrain screening is achieved using mask angle sectorisation and is intended for RAIM predications at aerodromes in uniquely terrain rich environments. This mode is has been developed specifically for RNP AR APCH predictions, where RAIM outages may have a high impact. In each instance, a terrain model yielding a 360° profile as observed from the Aerodrome Reference Point, or at waypoints used in the procedure (at the procedure altitude), is generated.

Once an aerodrome or route is entered into the GRPS, Users may define mask angles by Sector for the 360° profile to maximise the visible sky and ensure all available satellites are used for the RAIM prediction.


Current GRPS Users

Air France • Air Canada • ARINC Direct • Honeywell • Jeppesen • KLM • Rockwell Collins • Sabre Airline Solutions • Smart4Aviation • Universal Weather & Aviation Inc

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

A versatile and flexible service, GRPS seamlessly integrates into existing flightplanning suites and operations.