function abreise() {
    oFilterForm = document.forms[0];

    if ( ! oFilterForm ) {
        return true;
    }

    oDuration              = oFilterForm.mmc;
    oEarliestDepartureDate = oFilterForm.vnd;
    oLatestReturnDate      = oFilterForm.bsd;

    if ( ! oEarliestDepartureDate || ! oLatestReturnDate ) {
        return true;
    }

    var sDurationValue = 0;

    if ( oDuration ) {
        sDurationValue = oDuration.options[oDuration.selectedIndex].value;
    }

    var iDefaultDuration = 15;

    switch (sDurationValue) {
        case '0':
            iDuration = 28;
            break;
        case '1-5t':
            iDuration = 5;
            break;
        case '1w':
            iDuration = 7;
            break;
        case '6-8t':
            iDuration = 8;
            break;
        case '9-12t':
            iDuration = 12;
            break;
        case '2w':
            iDuration = 14;
            break;
        case '13-16t':
            iDuration = 16;
            break;
        case '3w':
            iDuration = 21;
            break;
        case '17-22t':
            iDuration = 22;
            break;
        case '4w':
            iDuration = 28;
            break;
        case '27-28t':
            iDuration = 28;
            break;
        case 'tr1':
        case 'tr2':
        case 'tr3':
            iDuration =iDefaultDuration;
            break;
        default:
            iDuration =iDefaultDuration;
            break;
    }

    if ( oLatestReturnDate.selectedIndex <
        (oEarliestDepartureDate.selectedIndex + iDuration)) {
        if ( (oEarliestDepartureDate.selectedIndex + iDuration) <=
            oLatestReturnDate.options.length ) {
            oLatestReturnDate.selectedIndex =
                oEarliestDepartureDate.selectedIndex + iDuration;
        } else {
            oLatestReturnDate.selectedIndex =
                oLatestReturnDate.options.length - 1;
        }
    }

    return true;
}