It's sort of hard to say.. easiest way is to search flighstats.com by Route, but you have to know what airport they're coming to. In my case that's easy because Denver International Airport is the only choice, but there are tons of airports in socal. It does look like Ontario seems to be their Cali airport of choice though, so.. maybe this one: http://www.flightstats.com/go/Fligh...=5X&flightNumber=918&departureDate=2009-06-19
I should also note that if it's this flight, your tracking info should update momentarily.