Area navigation, FMS and PBN

Navigation · Chapter 45 · DGCA CPL and ATPL

What RNAV is, the phantom-station waypoint, the FMS and its CDU, how the FMC blends IRS with radio fixes, and what RNP adds.

Remember

RNAV: any track within cover; B-RNAV ± 5 NM, P-RNAV ± 1 NM (95 %). 2D, 3D (+ vertical), 4D (+ time).
Simple RNAV: waypoint = radial/distance from a VOR/DME (phantom station); stay inside the DOC.
FMS: FMC + CDU, AP/FD, A/T, IRS; navigation database every 28 days.
FMC position = IRS + radio (DME/DME best) + GNSS, Kalman-filtered.
RNP = RNAV + on-board monitoring and alerting.

Fly where you like

Not beacon to beacon • rnav (area navigation): fly any track you like between points of your choice, without having to pass over the beacons • Same speed, same start. Watch who gets there first
What feeds it • It takes VOR/DME, DME, ILS, GNSS, INS/IRS, air data and time, and blends them into one best position
More routes in the same sky • The old way: every route ran from beacon to beacon, so everyone crowded over the same beacons
Side by side • RNAV: parallel and bypass routes, so more aircraft fit in the same sky with less separation • Shorter routes: less distance, time and fuel

How accurate, how many dimensions

B-RNAV • B-RNAV (basic, now called RNAV 5): stay within 5 NM of the track, 95 % of the time • India has RNAV 5 routes
P-RNAV • P-RNAV (precision, now RNAV 1): within 1 NM. Used for SIDs and STARs at busy airports • The corridor is drawn to the same scale
2D • 2D RNAV: guidance across the map only, left and right
3D • 3D: 2D plus a vertical path, up and down
4D • 4D: 3D plus time: you arrive at each point when planned