Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 15:55 and arrives at Hanoi Noi Bai International Airport at 18:05.
The flighttime is about 2h 10m. The distance travelled ("as the bird flies"): 593 Km. So the average speed is roughly 274 Km.
The best day to arrive at Bangkok is Thursday and it would be best to avoid Sunday, as prices are on average 129.85% higher than on Thursday. (Average prices, based on 925581 datapoints.)
We have a lot more statistics for flights VN 614 and between Bangkok and Hanoi.