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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.

PBN Applications and International Standards

RAIM prediction is a key enabler for PBN applications and these applications are supported by state and regional standards and advisory circulars. GRPS supports all PBN applications by conforming to these standards and advisory circulars thereby allowing operators to meet regulatory requirements.

  • RNP 10 (aka RNAV 10) - USA: FAA Order 8400.12() • Europe: EASA AMC 20-12 • Australia: CASA AC 91U-2(0) • Latin America: SVRSOP AC 91-001
  • RNAV 5 (aka B-RNAV) - USA: FAA AC 90-96() • Europe: EASA AMC 20-4 (JAA TGL 2) • Australia: CASA CAAP B-RNAV-1 • Canada: Transport Canada AC 700-015 • Latin America: SVRSOP AC 91-002
  • RNAV 2 (aka US RNAV Type A) - USA: FAA AC 90-100() • Europe: JAA TGL 10 (EASA AMC 20-16) • Australia: CASA AC 91U-II-3-B • Latin America: SVRSOP AC 91-003
  • RNAV 1 (aka US RNAV Type B; P-RNAV) - USA: FAA AC 90-100() • Europe: JAA TGL 10 (EASA AMC 20-16) • Australia: CASA AC 91U-II-3-B • Latin America: SVRSOP AC 91-003
  • RNP 4 - USA: FAA Order 8400.33 • Australia: CASA AC 91U-3(0) • New Zealand: CAA AC 91-10 • Latin America: SVRSOP AC 91-004
  • RNP 1 - USA: FAA AC 90-105() • Europe: JAA TGL 10 (EASA AMC 20-16) • Australia: CASA AC 91U-II-C-3(0) • Latin America: SVRSOP AC 91-006
  • RNP Approach - USA: FAA AC 90-105() (LNAV, LNAV/VNAV), AC 90-107() (LP, LPV) • Europe: EASA AMC 20-27 (LNAV, LNAV/VNAV) AMC 20-28 (LP, LPV) • Australia: CASA AC 91U-II-C-5 (LNAV), AC 91U-II-Attachment (LNAV/VNAV) • Latin America: SVRSOP AC 91-008 (LNAV), AC 91-010 (LNAV/VNAV)
  • RNP AR (Authorisation Required) Approach (aka SAAAR) - USA: FAA AC 90-101 • Europe: EASA AMC 20-26 • Australia: CASA AC 91U-II-C-5 (RNP AR) • Latin America: SVRSOP AC 91-009
  • MNPS - USA: FAA Notice N8110.60
RNP AR Predictions

The GRPS performs RAIM predictions for RNP AR APCH Operations down to 0.1 NM. This is a unique, proprietary service designed specifically to support ICAO PBN RNP AR procedures offering enhanced safety and reduced environmental impact.

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. 


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.

Multiple Delivery Channels

Users can select the devliery method that best suits their operational needs:
In addition, if there is an preferred alternative, DWI will work with the user to tailor an existing delivery method or develop a bespoke solution.

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.

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.