Flight Don Mueang International Airport departs from Bangkok Don Mueang International Airport at 18:25 and arrives at Hanoi Noi Bai International Airport at 20:20.
The flighttime is about 1h 55m. The distance travelled ("as the bird flies"): 606 Km. So the average speed is roughly 316 Km.
The best day to arrive at Bangkok is Friday and it would be best to avoid Sunday, as prices are on average 38.38% higher than on Friday. (Average prices, based on 169748 datapoints.)
This graph shows the distribution of prices found in the past years for this flight. (Average prices, based on 103 datapoints.)
We have a lot more statistics for flights FD 644 and between Bangkok and Hanoi.