AUGUR GPS RAIM Prediction Tool - Help

Warning: From 1 July 2012, AUGUR coverage will be limited to ECAC airspace only.
Please email the helpdesk (augur.helpdesk@ecacnav.com) for further information.

About Augur
Disclaimer
Mirror Site
GPS Status Tool
Terminal/Approach Tool
Visibility Tool
Route Tool
Augur Helpdesk

About AUGUR

AUGUR has been developed by EUROCONTROL to meet the requirements stated in:

  • Sub-section 5.2 (Normal Procedures) of section 5 (Operational Criteria For Use Of GPS Stand-Alone Equipment) of EASA AMC 20-4 (Airworthiness Approval and Operational Criteria For the Use of Navigation Systems in European Airspace Designated For Basic RNAV Operations), which states:

    Given a GPS constellation of 23 satellites or less (22 or less for GPS stand-alone equipment that incorporates pressure altitude aiding), the availability of GPS integrity (RAIM) should be confirmed for the intended flight (route and time). This should be obtained from a prediction program either ground-based, or provided as an equipment function or from an alternative method that is acceptable to the Authority.

    Dispatch should not be made in the event of predicted continuous loss of RAIM of more than 5 minutes for any part of the intended flight.

  • Sub-section 10.2.1.3 (Pre-flight Planning) of JAA TGL 10 (Airworthiness And Operational Approval For Precision RNAV Operations In Designated European Airspace), which states:

    If a stand-alone GPS is to be used for P-RNAV, the availability of RAIM must be confirmed with account taken of the latest information from the US Coastguard giving details of satellite non-availability.

    Note: RAIM prediction may be a function of the equipment provided that satellite non-availability data can be entered. In the absence of such a function, an airspace service provider may offer an approved RAIM availability service to users.

AUGUR informs a user of the number of operational satellites and provides a means by which the availability of GPS integrity can be confirmed for an intended flight.

AUGUR is intended to provide all of the information necessary to advise on GPS integrity for European aviation operations.

Disclaimer

In no event will EUROCONTROL or the maker of the Augur web-site be liable to the user of this web-site for any lost profits, lost savings or other incidental, indirect, special or consequential damages, arising out of the use of or inability to use the web-site.

The EUROCONTROL Augur web-site is provided on a strictly as-is basis and although great care is taken in both the collection of aeronautical data and the production of data materials delivered with the EUROCONTROL Augur web-site, complete accuracy cannot be guaranteed. GPS constellation information can change at any time and invalidate previously calculated results.

Errors brought to EUROCONTROL's attention will be corrected.

In case of contradiction between the contents of any EUROCONTROL Augur web-site data content and the those of the US Coast Guard, the content of the latter shall prevail.

Mirror Site

A mirror site is provided to increase the availability of the Augur service in the event of service outages at the primary site. The mirror site is a totally separate installation of the Augur service hosted in a different data centre. In the event of the primary site becoming unavailable, the primary site URL will be automatically switched over to be serviced by the mirror servers. The time taken to effect the switchover for all Augur users is outside the control of the Augur Service Provider and, to mitigate this issue, the mirror site is provided with its own URL - http://augur2.ecacnav.com. Users may wish to bookmark this URL to ensure that they have maximum access to the Augur service.

GPS Status Tool

GPS Status Tool is the default start page for the Augur application. GPS Status Tool presents a view of the GPS Satellite constellation based on the latest almanac and NANUs [Notice Advisory to Navigation Users] issued by the US Coast Guard. Information disseminated by the US Coast Guard can be found at the USCG NAVCEN web site.

GPS Status Tool presents the number of operational satellites in the GPS constellation based on the information current at the time of the request. The almanac used and NANUs that affect the availability of satellites during the requested time period are also displayed.

GPS Status Tool is configured to provide the status of the GPS constellation for a 72 hour period calculated from the midnight previous to the time at which the status request was made (times are in UTC).

Terminal/Approach Tool

Terminal/Approach Tool calculates the predicted RAIM availability for a 72 hour period for specific Aerodromes. It calculates RAIM Availability using one of two RAIM algorithms which have more stringent requirements for RAIM availability than the en-route RAIM calculation. The Terminal algorithm addresses the RAIM requirements for GNSS receivers operating in Terminal mode (1NM). The approach algorithm addresses the RAIM requirements for GNSS receivers operating in Approach mode (0.3NM).

Terminal/Approach Tool provides a graphical output and a tabular output each displaying the predicted RAIM outages over the scenario period for each of the selected aerodromes.

Terminal/Approach Tool is configured to return the status of the GPS constellation for a 72 hour period calculated from the midnight previous to the time at which the status request was made (times are in UTC).

Terminal/Approach Tool allows up to 10 aerodromes to be specified - aerodromes are selected by entering their ICAO identifier.

Terminal/Approach Tool calculates the predicted RAIM availability at the ARP for baro [pressure altitude] aided and non-baro aided GNSS user equipment at 1 minute intervals throughout the scenario time. The sample time is taken to be the mid-point of a 1 minute period. Therefore a RAIM outage detected at a single sample time will have a duration of 1 minute starting 30 seconds prior to the sample time and ending 30 seconds after the sample time.

Visibility Tool

Visibility Tool is supplementary to GPS Status Tool. While GPS Status Tool gives the minimum number of operational satellites in the GPS constellation over a 72 hour period, Visibility Tool calculates the location of the GPS satellites relative to a fixed receiver position for a given time duration.

Visibility Tool provides the following output options:

  • Graphical sky plot representation of the visible satellites.
    • Satellites are represented by coloured dots on the sky plot - one colour per satellite.
    • The satellite number is displayed in the satellite colour next to the dot representing the satellite position at the latest sample time.
    • Only visible and healthy satellites are displayed on the sky plot.
    • The area masked by the mask angle [between 0 and the mask angle value] is depicted as an opaque red area on the sky plot.
  • Tabular view satellite visibility.
    • A table of azimuth and elevation values and the visibility status for each satellite at each sample time in the scenario is displayed.
    • Azimuth and elevation are displayed in decimal degrees.
    • All satellites are included regardless of visibility and health.

Visibility Tool requires that the following information be entered:

  • Receiver Position - WGS-84 latitude and longitude in decimal degrees and WGS-84 height in metres.
  • Mask angle in degrees.
  • Scenario duration [valid values 0 hours 0 minutes through 23 hours 59 minutes]
  • Number of samples required to calculate the satellite visibility [valid values 1 through 20]. The samples will be spread evenly over the specified scenario duration with a sample always occurring at the start and the end of the scenario time.
  • UTC date and time if a start time other than the request time is required [entered time must be not more than 24 hours before or 48 hours after the request time]. If a time is not entered the scenario will start at the request time and end at request time + scenario duration.

The default values will be used if any input values are either invalid or out of range.

Route Tool

Route Tool calculates the predicted RAIM availability for points along a defined route using either the en-route or the terminal RAIM algorithm.

The route is defined by a series of waypoints selected, or input, by the user. The tool maintains a list of current en-route waypoints and navaids in the ECAC area which can be selected by ICAO identifier. The user can also define individual waypoints by entering an identifier, State, latitude and longitude - if the user wants to enter routes in terminal airspace he must use this option. The anticipated time elapsed since the route start time must be entered in the 'Time Offset' column for each waypoint. The algorithm to be used must also be selected for each waypoint - it is applied for the route segment following that waypoint.

The defined route and the results of the RAIM check may be saved and reviewed for the session but will be lost when the User leaves the Augur website.

The mask angle is set to 5 degrees as a default, although the User is provided with the capability to select other mask angles, should it be required. Both the Fault Detection (FD) and Fault Detection and Exclusion (FDE) algorithms are provided, with FD set as the default.

The tool calculates the anticipated RAIM availability for points spaced at one minute intervals along the route, based upon the Time Offset values entered, and displays any anticipated RAIM outages that equal or exceed 5 minutes. The sample time is taken to be the mid-point of a 1 minute period. Therefore a RAIM outage detected at a single sample time will have a duration of 1 minute starting 30 seconds prior to the sample time and ending 30 seconds after the sample time. It will only be displayed if the outage is predicted for 5 consecutive samples.

The Route Tool provides a graphical output and a tabular output each displaying the predicted RAIM outages over the scenario period. The graphic display also shows the anticipated outages if the start time is delayed, or brought forward, by 5, 10 or 15 minutes.

AUGUR Helpdesk

Further assistance is available by e-mailing the AUGUR Helpdesk: augur.helpdesk@ecacnav.com