private void InitFlights()
        {
            Flight flight1 = new Flight();
            Flight flight2 = new Flight();

            flight1.Id           = 1;
            flight2.Id           = 2;
            flight1.FlightNumber = FlightNumbers.Find(f => f.Airline == "EgyAir");
            flight2.FlightNumber = FlightNumbers.Find(f => f.Airline == "USAir");
            Flights.Add(flight1);
            Flights.Add(flight2);
            FlightNumbers.Find(fn => fn.Airline == "EgyAir").Flights = Flights;
            FlightNumbers.Find(fn => fn.Airline == "USAir").Flights.Add(flight2);
        }
        private void InitFlightNumbers()
        {
            FlightNumber flightNumber1 = new FlightNumber();
            FlightNumber flightNumber2 = new FlightNumber();

            flightNumber1.Airline            = "EgyAir";
            flightNumber1.Departure          = DateTime.Now;
            flightNumber1.Description        = "New Flight";
            flightNumber2.Airline            = "USAir";
            flightNumber2.Departure          = DateTime.Now;
            flightNumber2.Description        = "New Air Flight";
            flightNumber1.StartAirport       = Airports.Find(p => p.Id == 1);
            flightNumber1.DestinationAirport = Airports.Find(p => p.Id == 2);
            flightNumber2.StartAirport       = Airports.Find(p => p.Id == 2);
            flightNumber2.DestinationAirport = Airports.Find(p => p.Id == 1);
            FlightNumbers.Add(flightNumber1);
            FlightNumbers.Add(flightNumber2);
            Airports.Find(a => a.Id == 1).FlightNumbers = FlightNumbers;
            Airports.Find(a => a.Id == 2).FlightNumbers = FlightNumbers;
        }