***Meaning*** :: <u>R</u>eceiver <u>A</u>utonomous <u>I</u>ntegrity <u>M</u>onitoring ***Definition*** :: A system used to verify the usability of the received GPS signals and warns the pilot of any malfunction in the navigation system. This system is required for IFR-certified GPS units. ***Additional Info***: From [[IFH]] Ch9 - "RAIM needs a minimum of five satellites in view or four satellites and a barometric altimeter baro-aiding to detect an integrity anomaly. For receivers capable of doing so, RAIM needs six satellites in view (or five satellites with baro-aiding) to isolate a corrupt satellite signal and remove it from the navigation solution." - "Generally, there are two types of RAIM messages. One type indicates that there are not enough satellites available to provide RAIM and another type indicates that the RAIM has detected a potential error that exceeds the limit for the current phase of flight. Without RAIM capability, the pilot has no assurance of the accuracy of the GPS position." ***Source*** :: [[IFH]] Glossary #glossary #acronym