private void EditPassengerData()
 {
     if (SelectedPassenger != null)
     {
         PassengersInFlightModel newData = PassengersViewModel.EditPassengerData(SelectedPassenger, SelectedTrip, "new flight");
         newData.Id   = SelectedPassenger.Id;
         newData.Date = SelectedPassenger.Date;
         int n = Trips.IndexOf(SelectedTrip);
         int m = Trips[n].PassengersList.IndexOf(SelectedPassenger);
         Trips[n].PassengersList.RemoveAt(m);
         Trips[n].PassengersList.Insert(m, newData);
     }
 }