MSA: Minimum Safe Altitude. The elevation of thehighest obstruction near the aircraft plus a 1,000 or2,000 foot buffer added for safety. Innon-mountainous terrain, a 1,000 foot buffer is added.In mountainous terrain, a 2,000 foot buffer is added.The result is rounded to the nearest 100 feet.N Nautical Mile (nm): A distance measurement equalto 6,076 feet, or 1.15 statute mile. One nautical mile isalso equal to one minute of latitude.NAVSTAR: The name given to GPS satellites formedfrom the acronym for NAVigation System with TimeAnd Ranging.Non-Directional Beacon (NDB): A lowfrequency/medium frequency navigation aid sendingnon-directional signals that can be used fornavigation.O OBS: Omni-Bearing Selector.P Parallel Track Offset: A course that is parallel to thedesignated course, but offset to the right or left by agiven distance.PDOP: Position Dilution of Precision. See Dilution ofPrecision.PRN: GPS satellite Pseudo-Random Numbers areused to uniquely identify satellites. This is differentthan the SVN (Space Vehicle Number, or satelliteserial number). When excluding satellites from theRAIM Prediction , use the PRN number found on theNOTAMs and NANUs, not the SVN.R Radial: Any of the 360 magnetic courses from a VOR orsimilar navigational aid, beginning at the navigationalaid and proceeding outward in a straight line.15-8Glossary
