private void LoadData(string depCountry, string depCity, string arrCountry, string arrCity, string depAirport, string arrAirport, DateTime startDate, DateTime endDate, string clas, int numPers)
        {
            using (FlightServiceClient fsc = new FlightServiceClient())
            {
                this.lastFlightResults = fsc.getFlights(depCountry, depCity, arrCountry, arrCity, depAirport, arrAirport, startDate, endDate, clas, numPers);

                if (this.lastFlightResults == null)
                {
                    textBlock1.Text = "Geen resultaten gevonden, probeer de filter aan te passen.";
                }
                else
                {
                    textBlock1.Text = this.lastFlightResults.Count() + " vluchten gevonden.";

                    foreach (Flight f in this.lastFlightResults)
                        listBox1.Items.Add(f.departureCountry + ", " + f.departureCity + " -> " + f.arrivalCountry + ", " + f.arrivalCity);

                    if (listBox1.Items.Count > 0)
                        listBox1.SelectedIndex = 0;
                }
            }
        }