Flight Soekarno–Hatta International Airport departs from Jakarta Soekarno–Hatta International Airport at 08:30 and arrives at Semarang Achmad Yani International Airport at 09:40.
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 Monday and it would be best to avoid Tuesday, as prices are on average 31.28% higher than on Monday. (Average prices, based on 128775742 datapoints.)
We have a lot more statistics for flights JT 3504 and between Jakarta and Semarang.