public static void Main() { var regionalATC = new RegionalAirTrafficControl(); var aircraft1 = new Airbus380("AI568", regionalATC); var aircraft2 = new Boeing747("BA157", regionalATC); var aircraft3 = new Airbus380("LW111", regionalATC); aircraft1.Altitude += 100; aircraft3.Altitude = 1100; Console.WriteLine(aircraft1.Altitude); Console.WriteLine(aircraft2.Altitude); Console.WriteLine(aircraft3.Altitude); }