Section 5. Area Navigation Routes

20-5-1. DISCUSSION

a. RNAV systems permit navigation via a selected course to a predefined point without having to fly directly toward or away from a navigational aid. Several different types of airborne systems are capable of accurate navigation on an area basis.

b. RNAV aircraft are required to have the capability of operating along and within the lateral confines of VOR routes and airways. Therefore, current procedures and separation criteria remain the same for all RNAV aircraft cleared to operate along the conventional VOR route structure.

c. One item to be considered between area navigation and the present VOR/DME system is the effect of slant range error on aircraft position. Aircraft operating along the conventional VOR route structure are affected by DME slant range error in a relative manner and are primarily affected longitudinally since flightpaths are normally directly to or from ground stations. RNAV aircraft may be affected laterally as well as longitudinally since they do not have the disadvantage of having to operate directly to or from ground stations.

d. RNAV operations will use established and designated routes, up to and including FL 450, unless air traffic control radar is used to monitor navigation accuracy and aircraft separation.

e. A user must demonstrate that the equipment complies with accuracy criteria and must receive approval before the equipment can be used in the ATC system.

20-5-2. WAYPOINT CRITERIA

a. In accordance with paragraph 3-3-4, of this order, obtain five-letter pronounceable waypoint name/codes approval from AIM.

b. All magnetic bearings, distances between waypoints, and geographical coordinates of waypoints must be validated by AeroNav.

c. Each waypoint must be defined by geographical coordinates (e.g., degrees, minutes, seconds, hundredths of a second).

d. RNAV waypoints are used not only for navigation reference, but also for ATC operational fixes in much the same manner as VOR/DME ground stations and intersections are used in the conventional VOR structure. Waypoints are to be established along RNAV routes at:

1. The end points of RNAV routes.

2. Route turn points.

3. All holding fixes.

4. At any other point of operational benefit, such as route junction points where required for route clarity.

20-5-3. LATERAL PROTECTED AIRSPACE CRITERIA FOR RNAV EN ROUTE SEGMENTS

a. The criteria contained in this section are applicable to all established or designated RNAV routes except those portions of instrument departure procedures and Standard Terminal Arrival Routes (STARs) appropriate to the instrument departure procedures and STAR criteria. The lateral extent of RNAV routes designated in part 71 is coincident with the lateral protected airspace derived from this criteria.

b. The basic width of an RNAV route is 8 NM (4 NM on each side of the route centerline).

20-5-4. EN ROUTE TURN PROTECTION CRITERIA

Additional lateral airspace to be protected for course changes along RNAV routes at and above FL 180 must be in accordance with FAAO 7130.2, Airspace to Be Protected for Course Changes at and Above Flight Level 180. The airspace to be protected on the overflown side of the route centerline during course changes of more than 15 degrees along RNAV routes below FL 180 must be the lateral route width or 4 NM, whichever is greater, applied until the pilot reports on course. In effect, this means that the lateral dimensions of reduced route widths do not constitute fully protected airspace for aircraft during such course changes.