Please uncheck any airports you do not want in your selection, and then press the 'Show me how to get from Phl to Prg' button at the bottom of the screen.

Matches for PHL as three letter airport code or city name

Include	Airport name	Airport code	City	Country
	Philadelphia	PHL	Philadelphia PA	United States

Matches for PRG as three letter airport code or city name

Include	Airport name	Airport code	City	Country
	Prague - Ruzyne	PRG	Prague	Czech Republic