I tried making a route earlier, then made the return flight of that route (LGA-DCA). However, when looking at the altitude chart for DCA-LGA, the route is automatic set at cursing altitude, no climb or descent. LGA-DCA gives me proper climb, descent, and TOD indicators.

The tooltip on the red error message gives more information. Click the message or hover the mouse above.

See here for possible reasons: https://www.littlenavmap.org/manuals/littlenavmap/release/2.6/en/FLIGHTPLAN.html#error-display

BTW: If you see the three letter IATA codes everywhere in LNM: Reload the scenery library to fix this. LNM should show ICAO codes where available.

Alex

Ah, thanks.