The Malaysian government has released an image showing maximum distance aircraft could have travelled - is this based on range at cruise speed or less?
As far as I know, range can be extended by flying at slower than the typical cruise speed listed as 490 kt?
What is the best range speed?
Speed
The speed which gives the maximum range for a given aircraft weight and altitude is called best range speed. Flying at higher speeds than the best range speed increases the drag and the fuel flow, and therefore reduces the range. Lower speeds than the best range speed reduce the drag and the fuel flow, but they also reduce the distance traveled per time which is more dominant, and therefore reduce the range.
SKYbrary - AP4ATCO - Factors Affecting Aircraft Performance During Cruise