Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 17:15 and arrives at Jakarta Soekarno–Hatta International Airport at 20:55.
The flighttime is about 3h 40m. The distance travelled ("as the bird flies"): 830 Km. So the average speed is roughly 226 Km.
The best day to arrive at Bangkok is Wednesday and it would be best to avoid Sunday, as prices are on average 69.67% higher than on Wednesday. (Average prices, based on 13113646 datapoints.)
This graph shows the distribution of prices found in the past years for this flight. (Average prices, based on 436 datapoints.)
We have a lot more statistics for flights GA 869 and between Bangkok and Jakarta.