function checkAirport(place){
  var form=document.frmPost;
  var src;
  if(eval('form.frm'+place+'cb.selectedIndex')==0){
    return false;
  }
  return true; 
}
function checkDate(dateS){  //YYYYMMDD
  var year =dateS.substr(0,4);
  var month=dateS.substr(4,2);
  var day  =dateS.substr(6,2);
  var outDate= new Date(year,month-1,day);
  
  return (new Number(year)  == outDate.getYear() || new Number(year)  == (outDate.getYear()+1900)) &&
         new Number(month) == (outDate.getMonth()+1) &&
         new Number(day)   == outDate.getDate();
  return false;
}

function validateForm(){
  var form=document.frmPost;
  var fromSrc, toSrc;
//  form.frmOUTmy.value=form.frmOUTyear.value+form.frmOUTmonth.value;
//  form.frmRETmy.value=form.frmRETyear.value+form.frmRETmonth.value;

  if(!checkAirport('FROM')){
    alert("You have to select 'From' airport");
        return false;
  }
  if(!checkAirport('TO')){
    alert("You have to select destination airport");
        return false;
  }
  if(!checkDate(''+form.frmOUTmy.value+form.frmOUTday.value)){
    alert('You entered invalid fly out date');
    return false;
  }
  if(!((form.frmRETmy.value=='000000' && form.frmRETday.value=='00') || (checkDate(form.frmRETmy.value+form.frmRETday.value) && (''+form.frmRETmy.value+form.frmRETday.value >= form.frmOUTmy.value+form.frmOUTday.value)))){
    alert('You entered invalid returning date');
    return false;
  }
  return true;
}