Flight Don Mueang International Airport departs from Bangkok Don Mueang International Airport at 12:40 and arrives at Medan Kualanamu International Airport at 14:45.
The flighttime is about 2h 05m. The distance travelled ("as the bird flies"): 272 Km. So the average speed is roughly 131 Km.
The best day to arrive at Bangkok is Sunday and it would be best to avoid Monday, as prices are on average 37.5% higher than on Sunday. (Average prices, based on 469865 datapoints.)
This graph shows the distribution of prices found in the past years for this flight. (Average prices, based on 101 datapoints.)
We have a lot more statistics for flights QZ 155 and between Bangkok and Medan.