On the flightaware commercial services billing page for FlightXML, the times displayed for billing are incorrect. I believe that UTC times are shown, but for me, it shows PST as the timezone. Here is an excerpt. You can see that it says 18:00 PST, but it is only 11:00 PST now.
4 Enroute 2 2008-01-02 18:00 PST 2008-01-02 18:30 PST ***.***.***.***