Game seems fine.
Your aircraft fly all day everyday. That's 140 hours a week of aircraft hours per aircraft. Each aircraft requires 2-3 pilot hours for every aircraft hour (Dependant on cockpit crew size). 420 pilot hours required per aircraft per week.
In the EU pilots have an annual duty limit of 900 hours (I think, someone should propably check that). In order to work consistently throughout the 46 week work year a pilot would average 19.5 hours a week.
420/19.5 = 21.5 pilots required per aircraft per week. So the game math roughly checks out.
This does appear to be high. However, your aircraft are getting ridden more often than the whore of Babylon. Your staffing requirements are that of an airline twice the size of your's. If you reduced your utilisation to around 8-12 hours like a normal airline your staffing requirements will go down.