Flight Soekarno–Hatta International Airport departs from Jakarta Soekarno–Hatta International Airport at 18:00 and arrives at Semarang Achmad Yani International Airport at 19:10.
The flighttime is about 1h 10m. The distance travelled ("as the bird flies"): 415 Km. So the average speed is roughly 356 Km.
The best day to arrive at Jakarta is Wednesday and it would be best to avoid Thursday, as prices are on average 12.21% higher than on Wednesday. (Average prices, based on 128509035 datapoints.)
We have a lot more statistics for flights SL 610 and between Jakarta and Semarang.