Flight Achmad Yani International Airport departs from Semarang Achmad Yani International Airport at 15:30 and arrives at Jakarta Soekarno–Hatta International Airport at 16:40.
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 month to arrive at Semarang is March and the most expensive month to fly is June. (Average prices, based on 4620 datapoints.)
We have a lot more statistics for flights KL 241 and between Semarang and Jakarta.