function chooseSource() {
	var sTraveller = $('search_field_2');
	var sLocation = $('search_field');

	if (sTraveller.disabled == true) {
		sLocation.style.display = 'none';
		sLocation.disabled = true;
		sTraveller.value = sLocation.value;
		sTraveller.style.display = 'inline';
		sTraveller.disabled = false;
	}

	else {
		sTraveller.style.display = 'none';
		sLocation.style.display = 'inline';
		sLocation.value = sTraveller.value;
		sTraveller.disabled = true;
		sLocation.disabled = false;
	}
}