Flight Soekarno–Hatta International Airport departs from Jakarta Soekarno–Hatta International Airport at 20:00 and arrives at Medan Kualanamu International Airport at 22:15.
The flighttime is about 2h 15m. The distance travelled ("as the bird flies"): 895 Km. So the average speed is roughly 398 Km.
The best month to arrive at Jakarta is March and the most expensive month to fly is May. (Average prices, based on 6017 datapoints.)
We have a lot more statistics for flights NH 5503 and between Jakarta and Medan.