VATUSA
Virtual Air Traffic Simulation - USA Division
Airways And Route Systems
The route a pilot files in their flight plan will, many times, contain either one of two types of route systems, better known as airways. These two airway systems are referred to as; low altitude airway (designated with a V and called a Victor airway) and a high altitude airway (designated with a J and called a Jet route). Airways are often referred to as "highways in the sky.†That's because the United State's network of airways is very much like the national highway system †both serve the needs of the people. Most pilots flying in instrument conditions without visual reference to the ground follow airway or jet routes. Even pilots flying VFR will often file their flight plan making use of airways.
Low Altitude routes, Serve primarily smaller pistonâ€engine, propeller driven airplanes on shorter routes and at lower altitudes. Airways start at 1,200 feet above ground level (AGL) and extend upward to an altitude of 17,500 feet mean sea level (MSL).
Low Altitude airways are called "Victor" (V) airways, because they run primarily between VORs, and the phonetic alphabet's term for "V" is Victor. Airways can be found on enâ€route low altitude charts and have names like V240 or V37.
High Altitude routes, actually called jet routes primarily serve airliners, jets, turboprops, and turbocharged piston aircraft operating over longer distances above altitudes of 18,000 feet MSL. Jet routes start at 18,000 feet mean sea level (MSL) and extend upward to FL450 MSL. Jet routes can be found on enâ€route high altitude charts and have names like J42 or J121.
Aircraft flying at or above FL180 cannot use Victor airways in the route and likewise, aircraft flying below FL180 cannot use high altitude airways in their route.
A Minimum Safe Altitude (MSA) is the minimum altitude that a plane can safely fly on an airway. For example, the section of V134 between the PUC and PVU VORs has a MSA of 13,000. This is due to mountainous terrain in the area. Because of this, you cannot clear an aircraft that is making use of that section of airway at an altitude below 13,000. MSAs can be found on the high altitude or low altitude enroute charts.
Other Components of a Route
Now that you understand what airways are, let's look at a few more components of a route. The first is a VOR. VOR stands for VHF Omnidirectional Range. VOR, simply put, is a type of radio navigation system for aircraft. VORs broadcast a VHF radio signal encoding both the identity of the station and the angle to it, telling the pilot in what direction he lies from the VOR station, referred to as the radial. For example, if you were to start at a VOR and fly on a heading of 350 from that VOR, you would be on the 350 radial. VOR stations are used as intersections along airways. A typical airway will hop from station to station in straight lines. This is why jet and turbojet aircraft fly in straight lines, occasionally broken by a turn to a new course. These turns are often made as the aircraft passes over a VOR station. VORs are always abbreviated with three letters in a flight plan. If your having a hard time imagining what a VOR is, then think of a bicycle rim with 360 individual spokes. Imagine the VOR being the center of the rim, and the radials being the spokes of the rim. A pilot is able to fly any one of those spokes (a.k.a radials) to get TO or FROM the VOR.
Another component that can be found in some routes is a Nonâ€Directional Beacon (NDB). An NDB is merely a radio broadcast station used as a navigational aid for aircraft. NDB bearings provide a charted, consistent method for defining paths aircraft can fly, similar in the way a VOR does. NDBs are not as common in the United States as the VOR, and are usually found in lightlyâ€populated areas of developed countries since they can have a long range and are much less expensive to operate than VORs. Unlike a VOR, an NDB is abbreviated with either a 2 or 3 letter identifier.
One of the final components commonly seen in a route is the fix. Fixes, literally, are points in the sky. Fixes are plotted by finding the point where two radials, from two different VORs intersect. They may also be defined by a particular DME, or distance, off of a certain radial of a VOR, and in some cases are even defined as a point where a NDB course intersects a radial of a VOR.
