Preferred IFR routes and TEC routes

File direct between two busy airports and there is a good chance the clearance you read back looks nothing like what you filed. Preferred routes are the reason, and they are published.

What a preferred route is

The FAA publishes preferred IFR routes for city pairs where traffic flows need structure. They exist so that departures out of one metropolitan area do not conflict with arrivals into another, and they are what the automation expects to see. File one and your clearance usually matches your flight plan. File direct and you may get re-routed on the ground or in the air.

Low, high and tower enroute

Low altitude preferred routes apply below 18,000 feet, which is where most training and light general aviation flying happens. High altitude routes apply at and above FL180. Tower enroute control routes, usually written TEC, are a separate scheme for short IFR flights that stay under approach control the whole way without ever talking to a centre. TEC routes are especially common in southern California, Florida and the northeast corridor, and they are often the fastest way to get an IFR clearance for a short hop.

Reading the restrictions

A published route usually carries conditions. Some are jets only, some are props only, some require RNAV 1 with DME/DME/IRU or GPS, some have altitude bands attached, and some apply only during certain hours or in a certain direction. A route listed for turbojets at FL240 is not what Center is going to give a Warrior, and picking one off the list without reading the restriction is how students end up confused on the radio.

SIDs and STARs are not part of the enroute portion

Published routes often start with a departure procedure and end with an arrival. Those are flown as assigned and are not usually typed into your navlog as enroute fixes. The part that matters for planning is the middle: the fixes and airways between the departure structure and the arrival structure.

When your airport has nothing published

Preferred routes exist for busier city pairs, so a small field often has none. That does not mean the structure does not apply to you. If a nearby larger airport has a published route to your destination, ATC frequently assigns the same enroute fixes from your field, because the flows are the same. Looking at the neighbouring pair is a better guess than filing direct and hoping.

Where to look them up

The FAA publishes the database as part of the 28 day National Airspace System Resource subscription, and there is a query tool on the FAA site. EasyNavLog carries the same database: enter two airports in IFR mode and it lists what is published for that pair, tagged for piston or jet, with the altitudes and hours attached, and offers a nearby pair when your own airport has nothing. Picking one drops the enroute fixes straight into the navlog.

It is still a forecast of a clearance

A published route is what the system prefers, not a guarantee. Weather, flow control and the runway in use all change what you actually get. Check it against current charts, and expect the clearance to be the final word.

EasyNavLog is a planning and training aid, not a substitute for an official briefing. Verify every number against your POH or AFM, current charts and an approved weather source.