N39'
DRIVL
SAAGS
CORIM
HUGIN
FONIX
KIDER
BRAYMER
111.2 BQS[L] 49
NAPOLEON
114.0 ANX[L] 87
ROBINSON
108.2 RBA[L] 19
COLUMBIA 122.6
115.9 SUM 106
ST JOSEPH
Rosaceach Mem
[STJ]
Sherman AAF
(FLV)
Lawrence Muni
(LWC)
TOPEKA
Philip Billard Muni
(TOP)
Kansas City Intl
(MCI)
KANSAS CITY
Charles B Wheeler
Downtown
(MKC)
MOSBY
Midwest National
Air Control
(GPH)
Marshall Mem Muni
(MHI)
AGENT
26666 257
091°
190°
060°
080 263
Figure 2-31. IFR en route high altitude chart.
IFR En Route High Altitude Chart
En route high altitude charts provide aeronautical
information for navigation under IFR conditions at and
above FL 180. [Figure 2-31] High altitude charts include
the following information:
• Jet route structure
• RNAV Q-routes
• VHF radio aids to navigation (frequency, ID, channel,
geographic coordinates)
• Selected airports
• Reporting points
• Navigation reference system (NRS) waypoints
[Figure 2-32]
Jet routes are depicted in black with a “J” identifier followed
by the route number (e.g., “J12”) and are based on VOR or
Figure 2-32. Navigation reference system (NRS) waypoints.
W122°
N40°
247J189
J501 RED BLUFF
115.7 RBA 104
122.4
Chico Muni
(CIC)
KO63E
KO60E
Redding Muni
(RDD)
Red Bluff Muni
(RBL)
135 203
MEA-22000
MEA-24000D
MEA CAP
1300-06002MEA-24000D
MEA-26000D
Waypoint
Waypoint
RANCHO MURIETA
N40°05.93'
W122°14.18'
VORTAC NAVAIDs. [Figure 2-33] RNAV “Q” Route MEAs are
shown when other than 18,000 feet. [Figure 2-34] MEAs
for GNSS RNAV aircraft are identified with a “G” suffix.
MEAs for DME/DME/IRU RNAV aircraft do not have a “G”
suffix. All RNAV routes and associated data is charted in
aeronautical blue and magnetic reference bearings are
(OFTEC) SAKES
Green River Muni
(U34)
Honksville
MOAB
Camyonland’s Fld
(CNY)
MEA-33000
CEDAR CITY 111.2
Figure 2-33. High altitude jet routes.
Figure 2-34. MEAs on RNAV (Q) routes.
MEA-24000D
MEA-24000D
MEA-26000D
115.9 SUM 106
ENVIE
FINER
HOMEG
OTTOO
W123°
163 163 162
343 343
J12 Q7
MEA - 27000
MEA - 23000G
JointJet/RNAV Route
Figure 2-35. Joint jet/RNAV routes.
shown originating from a waypoint, fix/reporting point, or
NAVAID. When joint Jet/RNAV routes are depicted, the route
identification boxes are located adjacent to each other with
the route charted in black. [Figure 2-35] With the exception
of “Q” routes in the Gulf of Mexico, GNSS or DME/DME/IRU
RNAV equipment is required along with radar monitoring
capabilities. For aircraft that have DME/DME/IRU RNAV
equipment, refer to the CS for specific DME information.
VHF Airways
Victor airways are a system of established routes that
run along specified VOR radials, from one VOR station to
another. The purpose is to make flight planning easier
and they help ATC to organize and regulate the air traffic
flow. Almost all commercial flights are routed along these
airways but they are available for use by any pilot provided
that the proper altitudes are employed.
Victor Airway Navigation Procedures
The procedure for getting established on a victor airway
is to either fly directly to a nearby VOR or to intercept
an airway radial along the route of flight. Once the pilot
is established on an airway, it is important to follow the
procedures and guidelines put in place to ensure air traffic
separation and optimal safety on the airway. When using
victor airways for navigation, procedures do not allow the
pilot to jump from one VOR to another, but must navigate
from one to the next by using the alternating outbound/
inbound procedure of linking VORs. For example, when
departing from Zanesville VOR on V-214, the pilot selects
the 090° radial with a FROM indication on the course
deviation indicator (CDI) and should correct as necessary
to continuously maintain track on the centerline of the
airway. [Figure 2-36] The pilot should continue on this
course until it is time to change over to the inbound course
to the Bellaire VOR.
LF/MF Airways
The basic LF/MF airway width is 4.34 nautical miles (NM)
on each side of the centerline; the width expands by five
degrees when the distance from the facility providing
course guidance is greater than 49.66 NM. [Figure 2-37]
En Route Obstacle Clearance Areas
All published routes in the NAS are based on specific
obstacle clearance criteria. An understanding of en route
obstacle clearance areas helps with SA and may help avoid
controlled flight into terrain (CFIT). Obstacle clearance
areas for the en route phase of flight are identified as
primary, secondary, and turning areas.
The primary and secondary area obstacle clearance
criteria, airway and route widths, and the ATC separation
procedures for en route segments are a function of
safety and practicality in flight procedures. These flight
procedures are dependent upon the pilot, the aircraft, and
the navigation system being used, resulting in a total VOR
system accuracy factor along with an associated probability
SABGE
090°
N40°LORES
ZANDR
MUNCE
HISOM5
224 158
Barnesville Brodfield
(6G5)
1312 4DL
[2P7]
1187 L*28
Cambridge Muni
(CDI)
799 43L
Zoneville Muni
(ZZV)
900 50L
ZANESVILLE
111.4 ZZV 51
N42°34.15' W99°59.38'
CLEVELAND
122.5 122.2 122.1R
BELLAIRE
117.1AIR 118
N40°31.00' W99°49.04'
CLEVELAND
122.1R
CLEVELAND
Bolonl
120.4 257.975
Figure 2-36. Zanesville VOR/Victor Airway 214.
5°
NBD
4.34 NM
49.66 NM
NBD5°
5°
5°
Figure 2-37. LF/MR airway width.
factor. The pilot/aircraft information component of these
criteria includes pilot ability to track the radial and the flight
track resulting from turns at various speeds and altitudes
under different wind conditions. The navigation system
information includes navigation facility radial alignment
displacement, transmitter monitor tolerance, and receiver
accuracy. All of these factors were considered during
development of en route criteria. From this analysis, the
computations resulted in a total system accuracy of ±4.5°
95 percent of the time and ±6.7° 99 percent of the time.
The 4.5° value became the basis for primary area obstacle
clearance criteria, airway and route widths, and the ATC
separation procedures. The 6.7° value provides secondary
obstacle clearance area dimensions.
Primary and Secondary En Route Obstacle
Clearance Areas
The primary obstacle clearance area has a protected width
of 8 NM with 4 NM on each side of the centerline. The
primary area has widths of route protection based upon
system accuracy of a ±4.5° angle from the NAVAID. These
4.5° lines extend out from the NAVAID and intersect the
boundaries of the primary area at a point approximately
51 NM from the NAVAID. Ideally, the 51 NM point is where
pilots would change over from navigating away from the
facility, to navigating toward the next facility, although this
ideal is rarely achieved. [Figure 2-38]
4.5°
4.5°
4.5°
4.5°
4 NM
4 NM
Primary obstacle clearance area
Figure 2-38. Primary obstacle clearance area.
Primary en route obstacle clearance area
1,000 feet above highest obstacle
Figure 2-39. Non-mountainous obstacle clearance in the primary
area.
If the distance from the NAVAID to the change-over point
(COP) is more than 51 NM, the outer boundary of the
primary area extends beyond the 4 NM width along the
4.5° line when the COP is at midpoint. This means the
primary area, along with its obstacle clearance criteria, is
extended out into what would have been the secondary
area. Additional differences in the obstacle clearance area
result in the case of the effect of an offset COP or dogleg
segment. For protected en route areas, the minimum
obstacle clearance in the primary area, not designated as
mountainous under 14 CFR Part 95—IFR altitude, is 1,000
feet over the highest obstacle. [Figure 2-39] The secondary
obstacle clearance area extends along a line 2 NM on each
side of the primary area. Navigation system accuracy in
the secondary area has widths of route protection of a
Figure 2-41. Primary and secondary obstacle clearance area.
±6.7° angle from the NAVAID. These 6.7° lines intersect the
outer boundaries of the secondary areas at the same point
as primary lines, 51 NM from the NAVAID. If the distance
from the NAVAID to the COP is more than 51 NM, the
secondary area extends along the 6.7° line when the COP
is at mid-point. [Figure 2-40] In all areas, mountainous and
non-mountainous, obstacles that are located in secondary
areas are considered as obstacles to air navigation if they
extend above the secondary obstacle clearance plane.
This plane begins at a point 500 feet above the obstacles
(natural or man-made) upon which the primary obstacle
clearance area is based, and slants upward at an angle that
causes it to intersect the outer edge of the secondary area
at a point 500 feet higher. [Figure 2-41]
Changeover Points
When flying airways, pilots normally change frequencies
midway between NAVAIDs, although there are times
when this is not practical. If the navigation signals cannot
be received from the second VOR at the midpoint of the
route, a COP is depicted and shows the distance in NM to
each NAVAID. [Figure 2-42] COPs indicate the point where a
frequency change is necessary to receive course guidance
from the facility ahead of the aircraft instead of the one
6.7°
6.7°
6.7°
6.7°
4 NM
4 NM
2 NM
Secondary obstacle clearance area
2 NM
Figure 2-40. Secondary obstacle clearance area.
13,000 ft
13,000
Figure 2-42. Changeover points.
behind. These COPs divide an airway or route segment and
ensure continuous reception of navigation signals at the
prescribed minimum en route IFR altitude. They also ensure
that other aircraft operating within the same portion of
an airway or route segment receive consistent azimuth
signals from the same navigation facilities regardless of
the direction of flight.
Where signal coverage from two VORs overlaps at the MEA,
the COP normally is designated at the midpoint. Where
radio frequency interference or other navigation signal
problems exist, the COP is placed at the optimum location,
taking into consideration the signal strength, alignment
error, or any other known condition that affects reception.
The COP has an effect on the primary and secondary
obstacle clearance areas. On long airway or route segments,
if the distance between two facilities is over 102 NM and the
COP is placed at the midpoint, the system accuracy lines
extend beyond the minimum widths of 8 and 12 NM, and a
flare or spreading outward results at the COP . [Figure 2-43]
Offset COP and dogleg segments on airways or routes can
also result in a flare at the COP .
Direct Route Flights
Direct route flights are flights that are not flown on the
radials or courses of established airways or routes. Direct
route flights must be defined by indicating the radio fixes
over which the flight passes. Fixes selected to define the
route should be those over which the position of the aircraft
can be accurately determined. Such fixes automatically
become compulsory reporting points for the flight, unless
advised otherwise by ATC. Only those NAVAIDs established
Figure 2-43. Changeover point effect on long airway or route segment.
4.5°
6.7° 4.5°
6.7°70
4 NM
4 NM
Secondary areas
Primary areas
2 NM
2 NM
Flare
Flare
NOT FOR NAVIGATION
NOT FOR NAVIGATION
Figure 2-44. Direct route navigation.
for use in a particular structure (i.e., in the low or high
structures) may be used to define the en route phase of a
direct flight within that altitude structure.
Figure 2-44 shows a straight line on a magnetic course
from SCRAN intersection of 270° direct to the Fort Smith
Regional Airport in Arkansas that passes just north of
restricted areas R-2401A and B and R-2402. Since the airport
and the restricted areas are precisely plotted, there is an
assurance that you will stay north of the restricted areas.
From a practical standpoint, it might be better to fly direct
to the Wizer NDB. This route goes even further north of the
restricted areas and places you over the final approach fix
to Runway 25 at Fort Smith.
The azimuth feature of VOR aids and the azimuth and
distance (DME) features of VORTAC and TACAN aids are
assigned certain frequency protected areas of airspace that
are intended for application to established airway and route
use and to provide guidance for planning flights outside
of established airways or routes. These areas of airspace
are expressed in terms of cylindrical service volumes of
specified dimensions called class limits or categories.
An operational service volume has been established
for each class in which adequate signal 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 following:
1. Operations above FL 450—use NAVAIDs not more
than 200 NM apart. These aids are depicted on en
route high altitude charts.
2. Operation off established routes from 18,000 feet
MSL to FL 450—use NAVAIDs not more than 260
NM apart. These aids are depicted on en route high
altitude charts.
3. Operation off established airways below 18,000 feet
MSL—use NAVAIDs not more than 80 NM apart.
These aids are depicted on en route low altitude charts.
4. Operation off established airways between 14,500
feet MSL and 17,999 feet MSL in the conterminous
United States—(H) facilities not more than 200 NM
apart may be used.
Increasing use of self-contained airborne navigational
systems that do not rely on the VOR/VORTAC/TACAN
system has resulted in pilot requests for direct routes that
exceed NAVAID service volume limits. These direct route
requests are approved only in a radar environment with
approval based on pilot responsibility for navigation on the
authorized direct route. Radar flight following is provided
by ATC for ATC purposes. At times, ATC initiates a direct
route in a radar environment that exceeds NAVAID service
volume limits. In such cases, ATC provides radar monitoring
and navigational assistance as necessary.
When filing for a direct route flight, airway or jet route
numbers, appropriate to the stratum in which operation
is conducted, may also be included to describe portions
of the route to be flown. The following is an example of
how a direct route flight would be written.
MDW V262 BDF V10 BRL STJ SLN GCK
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.
Note: When route of flight is described by radio fixes,
the pilot is expected to fly a direct course between the
points named.
Pilots should keep in mind 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 en route charts pertain to those route
segments within controlled airspace, and those altitudes
may not meet obstruction clearance criteria when
operating off those routes.
Published RNAV Routes
Published RNAV routes are fixed, permanent routes that
can be flight planned and flown by aircraft with RNAV
capability. These are being expanded worldwide as
new RNAV routes are developed, and existing charted,
conventional routes are being designated for RNAV use. It
is important to be alert to the rapidly changing application
of RNAV techniques being applied to conventional en
route airways. Published RNAV routes may potentially be
found on any en route chart. The published RNAV route
designation may be obvious, or, on the other hand, RNAV
route designations may be less obvious, as in the case
where a published route shares a common flight track with
a conventional airway.
Note: The use of RNAV is dynamic and rapidly changing;
therefore, en route charts are continuously being updated
for information changes, and you may find some differences
between charts.
Basic designators for air traffic service (ATS) routes and
their use in voice communications have been established.
One of the main purposes of a system of route designators
is to allow both pilots and ATC to make unambiguous
reference to RNAV airways and routes. Basic designators
for ATS routes consist of a maximum of five, and in no
case to exceed six, alpha/numeric characters in order to be
usable by both ground and airborne automation systems.
The designator indicates the type of the route, such as
high/low altitude, specific airborne navigation equipment
requirements, such as RNAV, and the aircraft type using the
route primarily and exclusively. The basic route designator
consists of one or two letter(s) followed by a number from
1 to 999.
Composition of Designators
The prefix letters that pertain specifically to RNAV
designations are included in the following list:
1. The basic designator consists of one letter of the
alphabet followed by a number from 1 to 999. The
letters may be:
a. A, B, G, R—for routes that form part of the
regional networks of ATS route and are not
RNAV routes;
b. L, M, N, P—for RNAV routes that form part of
the regional networks of ATS routes;
c. H, J, V, W—for routes that do not form part of
the regional networks of ATS routes and are not
RNAV routes;
d. Q, T, Y, Z—for RNAV routes that do not form
part of the regional networks of ATS routes.
2. Where applicable, one supplementary letter must be
added as a prefix to the basic designator as follows:
a. K—to indicate a low level route established for
use primarily by helicopters;
b. U—to indicate that the route or portion thereof
is established in the upper airspace;
c. S—to indicate a route established exclusively for
use by supersonic aircraft during acceleration/
deceleration and while in supersonic flight.
3. Where applicable, a supplementary letter may be
added after the basic designator of the ATS route as
a suffix as follows:
Figure 2-45. Published RNAV jet routes.
NOT FOR NAVIGATION
N60°53.97´ W 151°2163´
114.3 ANC 221.3°-37.0
AMOTT
MEA-28000
J888R
J996R
J804R
61.2
61°
226°
AMOTT
a. F—to indicate that on the route or portion thereof
advisory service only is provided;
b. G—to indicate that on the route or portion thereof
flight information services only is provided;
c. Y—for RNP 1 routes at and above FL 200 to
indicate that all turns on the route between 30°
and 90° must be made within the tolerance of a
tangential arc between the straight leg segments
defined with a radius of 22.5 NM;
d. Z—for RNP 1 routes at and below FL 190 to
indicate that all turns on the route between 30°
and 90° should be made within the tolerance
of a tangential arc between the straight leg
segments defined with a radius of 15 NM.
Note: RNAV Q-routes require en route RNAV 2, corresponding
NAV/E2 code and PBN/C1-C4 based on navigation system
update source.
Use of Designators in Communications
In voice communications, the basic letter of a designator
should be spoken in accordance with the International Civil
Aviation Organization (ICAO) spelling alphabet. Where the
prefixes K, U, or S, previously mentioned, are used in voice
communications, they should be pronounced as:
K—Kopter
U—Upper, as in the English language
S—Supersonic
Where suffixes F, G, Y or Z specified in above, are used, the
flight crew should not be required to use them in voice
communications. Below is an example of how the letters
and numbers are spoken.
A11—Alpha Eleven
UR5—Upper Romeo Five
KB34—Kopter Bravo Thirty Four
UW456—Upper Whiskey Four Fifty Six