Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 07:00 and arrives at Hat Yai Hat Yai International Airport at 08:25.
The flighttime is about 1h 25m. The distance travelled ("as the bird flies"): 143 Km. So the average speed is roughly 101 Km.
The best day to arrive at Bangkok is Sunday and it would be best to avoid Wednesday, as prices are on average 138.24% higher than on Sunday. (Average prices, based on 312582 datapoints.)
We have a lot more statistics for flights TG 259 and between Bangkok and Hat Yai.