What is the purpose of a RAIM prediction?

Receiver Autonomous Integrity Monitoring (RAIM ) assesses the integrity of the Global Positioning System (GPS) signals. This system predicts outages for a specified geographical area. These predictions are based on the location, path, and scheduled GPS satellite outages.

What happens if you lose RAIM?

Loss of the required number of satellites in view, or the detection of a position error, cannot be displayed to the pilot by such receivers. In receivers with no RAIM capability, no alert would be provided to the pilot that the navigation solution had deteriorated, and an undetected navigation error could occur.

Is RAIM required for GPS?

IFR GPS units must automatically perform a RAIM check before beginning an approach. However, performing a RAIM check prior to leaving the ground will better enable pilots to plan ahead and is recommended specifically for pilots without baro-aiding (see below).

How long is a RAIM check good for?

Whilst a RAIM check may be performed in the aircraft, the result is only valid for +/- 15 minutes.

What is the difference between WAAS and RAIM?

RAIM uses redundant signals to produce several GPS position fixes and compare them, and a statistical function determines whether or not a fault can be associated with any of the signals. Among these is the WAAS system, which uses separate signals broadcast from different satellites to indicate these problems directly.

What causes RAIM outages?

(1) RAIM outages may occur due to an insufficient number of satellites or due to unsuitable satellite geometry which causes the error in the position solution to become too large.

How does GPS RAIM work?

RAIM uses redundant signals to produce several GPS position fixes and compare them, and a statistical function determines whether or not a fault can be associated with any of the signals. If the number of GPS satellites is 23 or fewer, RAIM availability must be checked using approved ground-based prediction software.

How many GPS do you need for RAIM?

24 GPS satellites
RAIM is considered available if 24 GPS satellites or more are operative. If the number of GPS satellites is 23 or fewer, RAIM availability must be checked using approved ground-based prediction software. Several GPS-related systems also provide integrity signals separate from GPS.

Do I need to check RAIM if I have WAAS?

WAAS enhances the reliability of the GPS system and thus no longer requires a RAIM check if WAAS coverage is confirmed to be available along the entire route of flight; in this case the pilot can plan the flight to a destination and file an alternate airport using only the WAAS navigation capabilities.

Is RAIM needed for WAAS?

How does RAIM work to predict GPS outages?

This system predicts outages for a specified geographical area. These predictions are based on the location, path, and scheduled GPS satellite outages. You can use RAIM to predict outages for a planned route or specific airport. Fields marked with * (Asterisk are mandatory.

How long does it take to make a RAIM prediction?

You can perform the RAIM prediction for any of the displayed flight plans. The prediction is performed based on the aircraft profile and route flown. The predictions are for a duration of +/- 60 minutes of the ETD at 15 min intervals with a sampling period of one minute. · Click View Graphically to view the Enroute outages graphically.

How are RAIM predictions used in flight planning?

RAIM predictions are based on satellite geometry, equipment RAIM capability (fault detection or fault detection and exclusion) and certification status (C129 or C146). TSO-specified GNSS equipment has several different modes used in flight planning and in flight, including:

What is the purpose of a RAIM prediction?