well one problem is that you are using
navigateToURL(); which is used to link to another webpage, not to run code in another file.
You want to use
URLLoader();
if you add the line
echo "&status=OK"; to the end of the php file (all php should be within <?php "your code" ?>) then your URLLoader will have a .data property that contains the var status == "OK"; after it successfully runs the php code.
you can go to
www.w3schools.com to learn about php if you want to add an if statement that will let you return OK or NOTOK or something like that.
Also, the data you send with the URLRequest.data has to be in the form of properties of an object, like
var myDataObject:Object = {firstVar:"Write me to a file", secondVar:"Me Too!"} and the php that is accepting this stuff has to have code like
$writeThis = $_REQUEST['firstVar'];
notice that I used the same variable name in both things.
there is no type declaration in php. $myVar could be an array, int, string, pointer to a file, whatever. the dollar ($) sign shows that it is a variable.