private void LoadData()
        {
            FlightsService service = Service.getInstanse().flightService;
            DataTable      AllFlightsTable;

            if (service.GetAllFlights(out AllFlightsTable))
            {
                IdTickets.Clear();
                foreach (DataRow row in AllFlightsTable.Rows)
                {
                    IdTickets.Add(Convert.ToInt32(row[0]));
                }
                AllFlightsTable.PrimaryKey = null;
                AllFlightsTable.Columns.RemoveAt(0);
                GridView.DataSource = AllFlightsTable;
                GridView.DataBind();
            }

            DropDownListDeparture.Items.Clear();
            DataTable FlightCityTable;

            if (service.GetFlightsCities(out FlightCityTable))
            {
                foreach (DataRow row in FlightCityTable.Rows)
                {
                    DropDownListDeparture.Items.Add((string)row[0]);
                }
            }
            OnChangeDepartureCity(null, EventArgs.Empty);
            UpdateEnableAddTicket();
        }