While there is no official indication as to the accuracy of the US Airways online flight tracker, some airline data is delayed from real time by up to 5 minutes. Other online flight trackers, such as FlightAware, aim for a delay of no more than 30 seconds.
In any case, the accuracy of flight trackers may be affected by weather conditions and airport congestion.
Another online flight tracker tool, which is available at the FlightStats website, takes these variables into account and acknowledges that accuracy cannot be guaranteed. Nevertheless, it assures users that its data will generally be reliable within a few minutes' margin of error.