I've been wondering about the fuel level as well. This plane, Boeing 777-200ER (ER stands for extended range), was built with trans-Atlantic flights in mind and has a potential range far beyond what's being discussed, even on the maps I've seen with the "theoretical maximum range" that extends well beyond the 4 hour circle. 7725 nautical miles is the rated maximum distance at max payload and this model has recorded flights well beyond that distance, including one eastbound on the great circle of over 12K miles from Seattle to Malaysia. From the boeing website, in 1997 "The 777-200ER (extended range), in Malaysia Airlines livery, established a new Great Circle Distance Without Landing record. The airplane flew from Boeing Field, Seattle, to Kuala Lumpur, Malaysia, covering 12,455.34 statute miles (20,044.20 km)."