Jet route. A route designated to serve flight operations from 18,000 feet MSL up to and including FL 450.
Jet stream. A high-velocity narrow stream of winds, usually found near the upper limit of the troposphere, which flows generally from west to east.
KIAS. Knots indicated airspeed.
Local area augmentation system (LAAS)
Localizer (LOC) ...
JET ROUTE- A route designed to serve aircraft operations from 18,000 feet MSL up to and including flight level 450. The routes are referred to as "J" routes with numbering to identify the designated route; e.g., J105.
(See Class A AIRSPACE.) ...
Jet routes start at 18,000 feet mean sea level (msl) and extend upward to an altitude of 45,000 feet msl (altitudes above 18,000 feet are called "flight levels" and are described as FL450 for 45,000 feet msl). Jet routes have names like J42 or J121.
Also in this section: ...
En Route High Altitude Charts portray Jet routes, distances, time zones, special use airspace, radar jet advisory areas, and other data. IFR flight plans are necessary for all flights above 18,000 feet.
"J" routes are Jet routes, used for flight above Flight Level 180- 18,000 feet. Below FL180 the "Victor" routes are used. (The chart above is just a sample that I drew up, and does not show the airway radials and other information that is displayed on an actual chart.) ...
all have names that start with the letter J, and are called Jet Routes. These run from 18,000 feet to 35,000 feet (5,486 meters to 10,668 meters). The altitude separating the low and high airway structures varies from country to country.
See also: What is the meaning of Aircraft, Flight, Navigation, Route, Pilot?