[iNils]

Если с проверками, то так

var xml:XML = <LOCATIONS>
	<LOCATION ID = "1" STATUS = "OPEN" />
	<LOCATION ID = "2" STATUS = "CLOSE" />
	<LOCATION STATUS = "OPEN" />
	<LOCATION ID = "4" STATUS = "CLOSE" />
	<LOCATION ID = "5" STATUS = "OPEN" />
	<LOCATION ID = "6"  />
</LOCATIONS>;
 
var openLocationsID:Vector.<uint> = new Vector.<uint>();
xml.*.(hasOwnProperty ("@ID") && hasOwnProperty ("@STATUS") && @STATUS == "OPEN" && openLocationsID.push(@ID));
 
trace (openLocationsID);