Airway (aviation)
Encyclopedia
In aviation
, an airway is a designated route in the air. Airways are laid out between navigational aid
s such as VOR
s, NDB
s and Intersection
s (NDB-based airways are rare in the United States
, but are more common in much of the rest of the world).
The first radiofrequency coordinated airways were first based on the old A-N Morse code
system. The pilot will listen for either the Morse code for A or N and the objective was to hear a steady tone (the A-N Morse codes are exactly opposite each other). Later on, the 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. There are still colored airways in existence today, mostly in Alaska. There is one colored airway off the coast of North Carolina called G13 or Green 13.
In the United States
, low altitude airways (below 18000 feet (5,486.4 m) MSL), appear on sectional charts, world aeronautical charts and en route low altitude charts and are designated by the letter "V" . High altitude airways (above 18000 feet (5,486.4 m) MSL), called jet
routes, appear on high altitude charts (that usually don't show topography, as the low altitude charts do) and are designated by the letter "J".
With the invention of RNAV
routes, the airway structure no longer has to be based on ground based navaids and a new naming convention is used. RNAV routes not based on VOR routes in low altitudes are preceded with the letter "T" while High airway routes are designated with the letter "Q". These RNAV routes are blue on low and high en-route charts produced by National Aeronautical Charting Office (NACO).
In the United States, Victor airways are Class E airspace from 1200 feet (365.8 m) AGL
to 18000 feet (5,486.4 m) MSL. The width of the victor corridor depends on the distance from the navigational aids (such as VOR's and NDB's). When VOR's are less than 102 NM from each other, the Victor airway extends 4 NM on either side of the center line (8 NM total width). When VOR's are more than 102 NM from each other, the width of the airway in the middle increases. The width of the airway beyond 51 NM from a navaid is 4.5 degrees on either side of the center line between the two navaids (at 51 NM from a navaid, 4.5 degrees from the center line of a radial is equivalent to 4 NM). The maximum width of the airway is at the middle point between the two navaids. This is when 4.5 degrees from the center radial results in a maximum distance for both navaids.
, airways are corridors 10 nautical miles (18.5 km) wide of controlled airspace
with a defined lower base, usually FL070-FL100, extending to FL195
. They link the major airports giving protection to IFR
flights during the climb and descent phases, and often for non-jet aircraft, cruise phases of flight. Historically they were laid out between VOR
s; however, advances in navigational technology mean that nowadays this is not always the case. Like European roads, 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 will be identical to the airway, prefixed with the letter "U".
In the UK, Airways are similar to Control Area and are corridor that are 10 nautical miles wide. They are all Class A.
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...
, an airway is a designated route in the air. Airways are laid out between navigational aid
Navigational aid
A navigational aid is any sort of marker which aids the traveler in navigation; the term is most commonly used to refer to nautical or aviation travel...
s such as VOR
VHF omnidirectional range
VOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice , and navigation signal. The identifier is typically a two- or three-letter string in Morse code...
s, NDB
Non-directional beacon
A non-directional beacon is a radio transmitter at a known location, used as an aviation or marine navigational aid. As the name implies, the signal transmitted does not include inherent directional information, in contrast to other navigational aids such as low frequency radio range, VHF...
s and Intersection
Intersection (aviation)
In aviation, an intersection is a virtual navigational fix that helps aircraft to maintain their flight plan. It is usually defined as the intersection of two VOR radials. They are usually identified as major airway intersections where aircraft, operating under instrument flight rules, often...
s (NDB-based airways are rare in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, but are more common in much of the rest of the world).
United States
The earliest airways in the United States were constructed by the US Post Office to guide airmail pilots on their delivery 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. However, these visual airways still 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.The first radiofrequency coordinated airways were first based on the old A-N Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
system. The pilot will listen for either the Morse code for A or N and the objective was to hear a steady tone (the A-N Morse codes are exactly opposite each other). Later on, the airways were based on Low / Medium Frequency ground stations, like the beat frequency oscillator (BFO) and the non-directional beacon
Non-directional beacon
A non-directional beacon is a radio transmitter at a known location, used as an aviation or marine navigational aid. As the name implies, the signal transmitted does not include inherent directional information, in contrast to other navigational aids such as low frequency radio range, VHF...
(NDB). These L/M frequency airways were the colored airways. There are still colored airways in existence today, mostly in Alaska. There is one colored airway off the coast of North Carolina called G13 or Green 13.
In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, low altitude airways (below 18000 feet (5,486.4 m) MSL), appear on sectional charts, world aeronautical charts and en route low altitude charts and are designated by the letter "V" . High altitude airways (above 18000 feet (5,486.4 m) MSL), called jet
Jet aircraft
A jet aircraft is an aircraft propelled by jet engines. Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes – as high as . At these altitudes, jet engines achieve maximum efficiency over long distances. The engines in propeller-powered aircraft...
routes, appear on high altitude charts (that usually don't show topography, as the low altitude charts do) and are designated by the letter "J".
With the invention of RNAV
Area navigation
Area Navigation is a method of Instrument Flight Rules navigation that allows an aircraft to choose any course within a network of navigation beacons, rather than navigating directly to and from the beacons. This can conserve flight distance, reduce congestion, and allow flights into airports...
routes, the airway structure no longer has to be based on ground based navaids and a new naming convention is used. RNAV routes not based on VOR routes in low altitudes are preceded with the letter "T" while High airway routes are designated with the letter "Q". These RNAV routes are blue on low and high en-route charts produced by National Aeronautical Charting Office (NACO).
In the United States, Victor airways are Class E airspace from 1200 feet (365.8 m) AGL
Above ground level
In aviation and atmospheric sciences, an altitude is said to be above ground level when it is measured with respect to the underlying ground surface. This is as opposed to above mean sea level , or in broadcast engineering, height above average terrain...
to 18000 feet (5,486.4 m) MSL. The width of the victor corridor depends on the distance from the navigational aids (such as VOR's and NDB's). When VOR's are less than 102 NM from each other, the Victor airway extends 4 NM on either side of the center line (8 NM total width). When VOR's are more than 102 NM from each other, the width of the airway in the middle increases. The width of the airway beyond 51 NM from a navaid is 4.5 degrees on either side of the center line between the two navaids (at 51 NM from a navaid, 4.5 degrees from the center line of a radial is equivalent to 4 NM). The maximum width of the airway is at the middle point between the two navaids. This is when 4.5 degrees from the center radial results in a maximum distance for both navaids.
Europe
In EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, airways are corridors 10 nautical miles (18.5 km) wide of controlled airspace
Controlled airspace
Controlled airspace is an aviation term used to describe airspace in which ATChas the authority to control air traffic, the level of which varies with the different classes of airspace. Controlled airspace is established mainly for three different reasons:...
with a defined lower base, usually FL070-FL100, extending to FL195
Flight level
A Flight Level is a standard nominal altitude of an aircraft, in hundreds of feet. This altitude is calculated from the International standard pressure datum of 1013.25 hPa , the average sea-level pressure, and therefore is not necessarily the same as the aircraft's true altitude either...
. They link the major airports giving protection to IFR
Instrument flight rules
Instrument flight rules are one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other are visual flight rules ....
flights during the climb and descent phases, and often for non-jet aircraft, cruise phases of flight. Historically they were laid out between VOR
VHF omnidirectional range
VOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice , and navigation signal. The identifier is typically a two- or three-letter string in Morse code...
s; however, advances in navigational technology mean that nowadays this is not always the case. Like European roads, 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 will be identical to the airway, prefixed with the letter "U".
In the UK, Airways are similar to Control Area and are corridor that are 10 nautical miles wide. They are all Class A.