Flight Soekarno–Hatta International Airport departs from Jakarta Soekarno–Hatta International Airport at 10:15 and arrives at Semarang Achmad Yani International Airport at 11:25.
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 Thursday and it would be best to avoid Monday, as prices are on average 15.17% higher than on Thursday. (Average prices, based on 132046931 datapoints.)
We have a lot more statistics for flights OD 6342 and between Jakarta and Semarang.