Aeronautical Information Manual (AIM), page 292

Index   291 -- Page 292 -- 293

coverage and frequency protection can be assured. To
facilitate use of VOR, VORTAC, or TACAN aids,
consistent with their operational service volume
limits, pilot use of such aids for defining a direct route
of flight in controlled airspace should not exceed the

(a) Operations above FL 450 - Use aids not

more than 200 NM apart. These aids are depicted on

enroute high altitude charts.

(b) Operation off established routes from
18,000 feet MSL to FL 450 - Use aids not more than
260 NM apart. These aids are depicted on enroute
high altitude charts.

(c) Operation off established airways below
18,000 feet MSL - Use aids not more than 80 NM
apart. These aids are depicted on enroute low altitude

(d) Operation off established airways be-
tween 14,500 feet MSL and 17,999 feet MSL in the
conterminous U.S. - (H) facilities not more than
200 NM apart may be used.

4. Increasing use of self-contained airborne
navigational systems which do not rely on the
VOR/VORTAC/TACAN system has resulted in pilot
requests for direct routes which exceed NAVAID
service volume limits. These direct route requests
will be approved only in a radar environment, with
approval based on pilot responsibility for navigation
on the authorized direct route. Radar flight following
will be provided by ATC for ATC purposes.

5. At times, ATC will initiate a direct route in a
radar environment which exceeds NAVAID service
volume limits. In such cases ATC will provide radar

monitoring and navigational assistance as necessary.

6. Airway or jet route numbers, appropriate to
the stratum in which operation will be conducted,
may also be included to describe portions of the route
to be flown.

Spelled out: from Chicago Midway Airport via Victor 262
to Bradford, Victor 10 to Burlington, Iowa, direct

St. Joseph, Missouri, direct Salina, Kansas, direct
Garden City, Kansas.
When route of flight is described by radio fixes, the pilot

will be expected to fly a direct course between the points
7. Pilots are reminded that they are responsible
for adhering to obstruction clearance requirements on
those segments of direct routes that are outside of
controlled airspace. The MEAs and other altitudes
shown on low altitude IFR enroute charts pertain to

those route segments within controlled airspace, and

those altitudes may not meet obstruction clearance

criteria when operating off those routes.
d. Area Navigation (RNAV)

1. Random impromptu routes can only be
approved in a radar environment. Factors that will be
considered by ATC in approving random impromptu
routes include the capability to provide radar
monitoring and compatibility with traffic volume and
flow. ATC will radar monitor each flight, however,
navigation on the random impromptu route is the
responsibility of the pilot.

2. Pilots of aircraft equipped with approved area
navigation equipment may file for RNAV routes
throughout the National Airspace System and may be
filed for in accordance with the following procedures.

(a) File airport-to-airport flight plans.
(b) File the appropriate RNAV capability
certification suffix in the flight plan.

(c) Plan the random route portion of the flight
plan to begin and end over appropriate arrival and
departure transition fixes or appropriate navigation
aids for the altitude stratum within which the flight
will be conducted. The use of normal preferred
departure and arrival routes (DP/STAR), where
established, is recommended.

(d) File route structure transitions to and from

the random route portion of the flight.
(e) Define the random route by waypoints.
File route description waypoints by using degree-
distance fixes based on navigational aids which are
appropriate for the altitude stratum.
(f) File a minimum of one route description

waypoint for each ARTCC through whose area the

random route will be flown. These waypoints must be
located within 200 NM of the preceding center's
(g) File an additional route description
waypoint for each turnpoint in the route.

5-1-14 Preflight

Page 292 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   291 -- Page 292 -- 293