Designated route along which aircraft travel between airports
This article is about aviation flight corridors. For walkways, see
Jet bridge
. For companies that provide air transport services called "airways", see
Airline
. For other uses, see
Airway (disambiguation)
.
In the United States,
airways
[1]
or
air routes
are defined by the
Federal Aviation Administration (FAA)
in two ways:
"VOR Federal airways and Low/Medium Frequency (L/MF) (Colored) Federal airways"
[2]
These are designated routes which
aeroplanes
fly to aid in navigation and help with separation to avoid accidents.
[3]
[4]
[5]
[a]
Airways are defined with segments within a specific altitude block, corridor width, and between fixed geographic coordinates for
satellites navigation system
, or between ground-based
radio transmitter
navigational aids
(navaids; such as
VORs
or
NDBs
) or the
intersection
of specific radials of two navaids.
United States
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To guide airmail pilots on their delivery routes, the
United States Postal Service
constructed the first airways in the United States, the
Contract Air Mail routes
. These airways were between major cities and identified at night by a series of flashing lights and beacons which pilots flew over in sequence to get from one city to the next.
[6]
Intermediate fields were located every 30 miles (48 km) in case of emergencies, with at least two landing strips a minimum of 2,000 feet (610 m) in length, and 600 feet (180 m) in width. Rotating airways beacons were erected every 10 miles (16 km).
[7]
However, these visual airways required the pilots to be in visual contact with the ground, which precluded flying in fog or clouds. Subsequently, the Department of Commerce funded the development of other means of airway navigation.
[8]
The first airways to be delineated by radio frequency were based on the old
Low-frequency radio range
also called the "Four Course Radio Range" or "A/N" system. The pilot listened for the stronger of the Morse codes transmitters ("· ?" for "A" and "? ·" for "N", indicating left or right of the course); the objective was to be centered on course hearing a steady tone (the A and N Morse codes merge to form a steady tone when the receiver is equidistant from both transmitters).
Later airways were based on low/medium frequency ground stations, like the
beat frequency oscillator
(BFO) and the
non-directional beacon
(NDB). These L/M frequency airways were the
colored airways
. Colored airways still exist, mostly in Alaska. There are only a few colored airways remaining in the contiguous United States. There is one colored airway on the coast of North Carolina called G13 (Green 13). Additionally, there are several colored airways connecting to, and transitioning through, the Florida Keys. B9 (Blue 9) connects the Southern Florida mainland to Marathon Key. B646 (Blue 646) connects Merida, Mexico to
Nassau, Bahamas
and transitions through the Florida Keys. A portion of B646 connects Key West to Marathon Key and serves as a bypass for aircraft unable to meet the 15,000 foot minimum altitude along that portion of V3. Finally, G765 (Green 765) connects Key West to Cozumel, Mexico. Colored airways are all depicted in brown on low and high altitude charts produced by the
FAA
's Aeronautical Navigation Products.
Low altitude airways (below 18,000 feet (5,500 m)
MSL
) that are based on VOR stations, appear on sectional charts, world aeronautical charts, and en route low altitude charts and are designated with the prefix "V" (pronounced
victor
, hence,
victor airways
). High altitude airways (from 18,000 feet (5,500 m) MSL to
FL450
) based on VOR stations are called
jet
routes; they appear on high altitude charts (that usually do not show topography, as the low altitude charts do) and are prefixed by the letter "J". VOR-based routes are depicted in black on low and high altitude charts produced by the FAA's Aeronautical Navigation Products.
With the invention of
RNAV
routes, airway structure no longer has to be based on ground-based navaids; a new naming convention is used. RNAV routes not based on VOR routes in low altitudes are preceded with the letter "T"; high airway routes are designated with the letter "Q". RNAV routes are depicted in blue on low and high altitude charts produced by the FAA's Aeronautical Navigation Products.
Europe
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Airways are corridors 10 nautical miles (19 km) wide of
controlled airspace
with a defined lower base, usually
FL070?FL100
, extending to FL195. They link major airports giving protection to
IFR
flights during the climb and descent phases, and often for non-jet aircraft, cruise phase of flight. Historically, they were laid out between
VORs
; however, advances in navigational technology mean that this is no longer a necessity. Each airway has a designator containing one letter and one to three numbers. All airspace above FL195 is class C controlled airspace, the equivalent to airways being called Upper Air Routes and having designators prefixed with the letter "U". If an upper air route follows the same track as an airway, its designator is the letter "U" prefix and the designator of the underlying airway.
In the UK, airways are all class A below FL195 and, therefore,
VFR
flights are prohibited.
Air corridor
[
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]
"Air corridor" redirects here. For the Mozambiquean airline, see
Air Corridor
.
An air corridor is a designated region of
airspace
that an aircraft must remain in during its transit through a given region. Air corridors are typically imposed by military or diplomatic requirements. During the
Berlin Blockade
, for example, pilots flying across Soviet-controlled
German
airspace were required to maintain very specific positioning within
air corridors
defined by the commander in charge of the airlift. Subsequent flights, both military and civilian, between
West Germany
and
West Berlin
during the
Cold War
were required to remain within their designated corridor or risk being shot down.
Air corridors should not be confused with airways. Airways are navigational aids which a pilot generally may deviate from when circumstances warrant, while compliance with a designated air corridor is mandatory.
Notes
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]
- ^
The term
airway
is used by aviation professionals including the
International Civil Aviation Organization
(ICAO), but other terms have been used or misused by non-specialist sources, sometimes to mean the same thing.
References
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External links
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