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Aeronautical Charts Terms and Symbols
IFR Aeronautical Charts
Explanation of IFR Terms and Symbols

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Aeronautical Charts
Terms and Symbols

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Explanation of VFR Terms
and Symbols

VFR Chart Symbols

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IFR Aeronautical Charts

Explanation of IFR
Terms and Symbols

IFR Chart Symbols

IFR Enroute Low/High
Altitude
(US and Alaska Charts)

Oceanic Route Charts
North Atlantic and
North Pacific Route Charts


Joint Victor/RNAV routes will be charted as outlined
above except as noted. The joint Victor route and
the RNAV route identification box shall be shown adjacent
to each other. Magnetic reference bearings will
not be shown. MEAs will be stacked in pairs or in two
separate columns, GNSS and Victor. On joint routes,
RNAV specific information will be printed in blue.

MILITARY TRAINING ROUTES (MTRs)
Military Training Routes (MTRs) are routes established
for the conduct of low-altitude, high speed
military flight training (generally below 10,000 feet MSL
at airspeeds in excess of 250 knots IAS). These routes
are depicted in brown on Enroute Low Altitude Charts,
and are not shown on inset charts or on IFR Enroute
High Altitude Charts. Enroute Low Altitude Charts depict
all IR (IFR Military Training Route) and VR (VFR
Military Training Route) routes, except those VRs that
are entirely at or below 1500 feet AGL.

OFF ROUTE OBSTRUCTION CLEARANCE ALTITUDE
(OROCA)

The Off Route Obstruction Clearance Altitude
(OROCA) is represented in thousands and hundreds
of feet above mean sea level. The OROCA represents
the highest possible elevation including both terrain
and other vertical obstructions (towers, trees., etc.)
bounded by the ticked lines of latitude and longitude.
In this example the OROCA represents 12,500 feet.

OROCA is computed just as the Maximum
Elevation Figure (MEF) found on Visual charts except
that it provides an additional vertical buffer of 1,000
feet in designated non-mountainous areas and a 2,000
foot vertical buffer in designated mountainous areas
within the United States. For areas in Mexico and the
Caribbean, located outside the U.S. ADIZ, the OROCA
provides obstruction clearance with a 3,000 foot vertical
buffer. Unlike a MEF, when determining an OROCA
the area 4 NM around each quadrant is analyzed for
obstructions. Evaluating the area around the quadrant
provides the chart user the same lateral clearance an
airway provides should the line of intended flight follow
a ticked line of latitude or longitude. OROCA does not
provide for NAVAID signal coverage, communication
coverage and would not be consistent with altitudes
assigned by Air Traffic Control. OROCAs can be found
over all land masses and open water areas containing
man-made obstructions (such as oil rigs). OROCAs are
shown in every 30 x 30 minute quadrant on Area Charts,
every one-degree by one degree quadrant for U.S. Low
Altitude Enroute Charts and every two-degree by two
degree quadrant on Alaska Low Enroute Charts.

Military Training Routes are identified by designators
(IR-107, VR-134) which are shown in brown
on the route centerline. Arrows indicate the direction
of flight along the route. The width of the route determines
the width of the line that is plotted on the chart:
Route segments with a width of 5 NM or less, both
sides of the centerline, are shown by a .02" line.

Route segments with a width greater than 5
NM, either or both sides of the centerline, are shown
by a .035" line.

MTRs for particular chart pairs (ex. L1/2, etc.)
are alphabetically, then numerically tabulated. The tabulation
is located on the title panel and includes MTR
type and unique ident and altitude range.

JET ROUTE SYSTEM (HIGH ALTITUDE ENROUTE
CHARTS)

Jet routes are based on VOR or VORTAC navaids,
and are depicted in black with a "J" identifier
followed by the route number (e.g., "J12"). In Alaska,
Russia and Canada some segments of jet routes are
based on LF/MF navaids and are shown in brown instead
of black.

 


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