GPS, RNAV, and PBN Essentials

Navigation to points in space defined by latitude/longitude rather than to ground transmitters, enabling direct routes and approaches at airports with no ground navaids.

The required accuracy, integrity, continuity, and functionality for a route or procedure — any equipment meeting those requirements may be used.

Four — three spheres intersect at a point, but a fourth is needed to solve for the receiver's imprecise clock (time).

Receiver Autonomous Integrity Monitoring: 5 satellites to detect a faulty signal, 6 to identify and exclude it (FDE).

Non-WAAS operators, for destination ETA (and alternate), using the FAA SAPT, Flight Service, or the avionics' own prediction page.

Ground reference stations measure GPS errors and uplink corrections via geostationary satellites, giving ~1–2 m accuracy and near-instantaneous integrity alerting.

RNP includes on-board performance monitoring and alerting — it tells the crew when required accuracy can no longer be met.

RNAV 2 for enroute T/Q-routes, RNAV 1 for SIDs and STARs, RNP APCH = 1 NM terminal and 0.3 NM final.

2 NM full-scale enroute, 1 NM within 30 NM of destination, then 0.3 NM (or angular with WAAS) at the FAF — a cue approach mode has armed.

LNAV+V is lateral with advisory glidepath flown to an MDA; LNAV/VNAV is APV with baro/WAAS vertical flown to a DA; LPV is angular lateral and vertical, ILS-like, flown to a DA.

Authorization Required approaches down to RNP 0.1 with curved (RF) legs, requiring special aircraft and crew approval.