Valid FL's


Ran a FP for altitudes between FL350 and FL450 for KDXR-KFXE. FlightAware Flight Plan Options: gave me options for FL360, 380, 400, 420, 440. FL 420 and FL440 are not valid FL’s.

After FL410 you leave RVSM airspace and are back to 2000’ altitude separation of FL430, FL450, etc.


I’m not sure that I understand. Your flight is westbound, so FlightAware is proposing even altitudes.


FL420 and FL440 are not valid flight levels.

The next valid westbound FL above FL400 is FL430. The next valid eastbound FL above FL410 is FL450.

RVSM airspace is FL290-FL410 where you have 1000’ separation and you have even/odd FL’s.

Above FL410 you are back to 2000’ altitude separation. Westbound altitudes are FL430, FL470, FL510. Eastbound FL’s are Fl450, FL490.

You should still give FL430 and FL450 regardless of direction for planning since there is little traffic at FL450 and it is often available for the wrong direction if requested.


Daniel, ajw22 is correct, and I agree that Flight Levels 410, 430, 450, 470, 490, and 510 should be made available for planning (regardless of direction). It is not uncommon to see aircraft at altitudes at FL450 and above. Even the occasional Gulfstream or Global at FL510.


Thanks, guys, I’ll send this on to the dev team.