('#results').empty();
    $('.error').removeClass('error');
    var inputOrigin = $('#flight-from').val();
    var inputDestination = $('#flight-to').val();
    var inputDate = $('#datepicker').val();

    // input validation. if the text inputs are invalid, or blank, outline them in red.
    if(inputOrigin === '' || DOMESTIC_FLIGHTS.indexOf(inputOrigin) === -1)
      $('#flight-from').addClass('error');
    if(inputDestination === '' || DOMESTIC_FLIGHTS.indexOf(inputDestination) === -1)
      $('#flight-to