Flight Soekarno–Hatta International Airport departs from Jakarta Soekarno–Hatta International Airport at 19:00 and arrives at Medan Kualanamu International Airport at 21:20.
The flighttime is about 2h 20m. The distance travelled ("as the bird flies"): 895 Km. So the average speed is roughly 384 Km.
The best month to arrive at Jakarta is May and the most expensive month to fly is December. (Average prices, based on 4528 datapoints.)
We have a lot more statistics for flights OD 302 and between Jakarta and Medan.