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Asked by: 2080 views Airspace, FAA Regulations

I am somewhat confused with RAIM regarding WAAS GPS navigators and IFR approved non-WAAS GPS navigators.

After reviewing the AIM, my interpretation is that WAAS  GPS units do not use RAIM but a non-WAAS IFR approved GPS navigator uses RAIM? Is this correct? If WAAS units do not use RAIM, what do WAAS use for GPS signal integrity?

Any feedback always appreciated.

Excerpt below from AIM 1-1-19:

Receiver Autonomous Integrity Monitoring (RAIM). When GNSS equipment is not using integrity information from WAAS or LAAS, the GPS navigation receiver using RAIM provides GPS signal integrity monitoring. RAIM is necessary since delays of up to two hours can occur before an erroneous satellite transmission can be detected and corrected by the satellite control segment. The RAIM function is also referred to as fault detection. Another capability, fault exclusion, refers to the ability of the receiver to exclude a failed satellite from the position solution and is provided by some GPS receivers and by WAAS receivers.


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2 Answers

  1. Best Answer

    John D. Collins on Apr 19, 2013

    WAAS GPS don’t use RAIM when they are in the coverage area for WAAS. This is because part of the WAAS satellite transmissions include integrity data for each satellite.

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  2. Dan Chitty on Apr 19, 2013

    Thank you for the feedback.

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