United Kingdom Division
Airways are currently an essential part of travelling by plane; they connect Fixes and radio navigation aids to form a route, which aircraft must follow. They allow for even distribution of traffic, and ensures that controllers know where aircraft will be at any one time. Airways are also known as Air Traffic Service Routes, or ATS Routes.
In the UK, there are currently two categories of ATS Routes in use;
| ATS Route Designator | Description |
|---|---|
| L, M, N, P | Routes for area navigation which form part of the regional networks of ATS routes. |
| Q, T, Y, Z | Routes for area navigation which do not form part of the regional networks of ATS routes |
In the London (EGTT) FIR, airways and ATS routes must be used for a valid IFR flight plan, unless non-standard procedures are to be followed. In the Scottish (EGPX) FIR, free route airspace is in use.
In the UK, all of the airspace at FL195 and above is designated as Class C. We designate airways that cross FL195 as 'Upper' airways. These are shown through the letter 'U' being added as a prefix to the airway (i.e. UL9, or UM185).