Preprogrammed holding pattern (preprogrammed hold). A hold that is published as a part of an instrument procedure (e.g., approach, missed approach) and has been loaded into the FMS/RNAV. Some FMS/RNAV units automatically enter and fly the holding procedure when it is encountered. Others must be flown around the depicted holding pattern, usually by changing the heading (bug). Some units require switching to the nonsequencing or OBS mode so the active waypoint remains set to the designated holding fix. 

Preprogrammed course reversal. A course reversal (commonly called a “procedure turn”) that appears as part of an instrument approach procedure that has been loaded into the FMS/RNAV. Many FMS/RNAV units automatically attempt to perform the course reversal procedure when it is encountered. Others require the pilot to navigate the depicted procedural track manually or by using the heading mode to fly the depicted track. 

Primary flight display (PFD).  An electronic flight display that presents the primary flight instruments, navigation instruments, and other information about the status of the flight in one integrated presentation. Primary‑secondary task inversion. Situation in which the pilot ceases to monitor the situation directly and simply listens for system alerts. 

RA.  See resolution advisory. 

Radar attenuation.  The absorption or reflection of radar signals by a weather cell, preventing that radar from detecting any additional cells that might lie behind the first cell. 

RAIM. See receiver autonomous integrity monitoring. Receiver autonomous integrity monitoring. The self‑ monitoring function performed by a TSO‑129 certified GPS receivers to ensure that adequate GPS signals are being received at all times. The GPS will alert the pilot whenever the integrity monitoring determines that the GPS signals do not meet the criteria for safe navigation use. 

Receiver autonomous integrity monitoring. The self‑ monitoring function performed by a TSO‑129 certified GPS receiver to ensure that adequate GPS signals are being received at all times. The GPS alerts the pilot whenever the integrity monitoring determines that the GPS signals do not meet the criteria for safe navigation use. 

Resolution advisory (RA). A warning issued by the Traffic Collision Avoidance System (TCAS) indicating an immediate threat of collision with another aircraft. This warning takes the form of a command to perform a vertical avoidance maneuver (e.g., “Climb! Climb!”) These commands are products of TCAS II equipment. These commands take precedence over ATC instructions, but must be reported to ATC immediately upon receipt and execution. 

Risk homeostasis.  A term coined by psychologist Gerald J. S. Wilde, a tendency for humans to seek target levels of risk. 

RNAV.  See Area Navigation. 

RNAV (GPS) approach.  An approach procedure based on GPS signals for guidance. 

Route discontinuity.  A point of uncertainty in a route that has been programmed into an FMS/RNAV. Most systems display this message when there is no routing to connect the last waypoint to the next point, or there is a missing next point. FMS/RNAV units will not plan to go direct unless certain programming parameters are met. 

Sequencing mode.  The FMS/RNAV mode that automatically sequences along the waypoints in the programmed route. The sequencing mode alerts the pilot to upcoming waypoints, and offers guidance to each successive waypoint in the route. 

Stand-alone approach.  An instrument approach that relies solely on the use of RNAV equipment. If flown with GPS/ WAAS enabled certified equipment in accordance with TSO‑C145A or TSO‑146A installed in accordance with the provisions of AC 20‑130A or 138A, no conventional navigation equipment alternate approach (VOR/ILS) requirements are necessary, as when flying with TSO‑C129 certified equipment. 

Subpage. An additional page of information about a particular topic that can be displayed on an FMS/RNAV. Many pages require the use of several subpages to show all information pertaining to any one topic. 

SUSP.  See suspend mode. 

