ATC, knowing checklist procedures (knowing what to press, in what sequence,.. when.. why.. double and triple checking it.. ) -- Then knowing how to operate the , at first, seemingly endless array of avionics for flight. Especially auto pilot equipmpent, from Altitude Holds, VS, IAS, HDG, CRS, Com frequencies, Nav Frequencies, .. learning the use of ADF, DME, what your transponder is , and why -- Even learning the proper methods of employing ILS driven approaches to major airports (aka: Fly by wire" ) -- Which is not nearly as easy as it sounds. Planes DO fly themselves.. sort of. But ultimately the pilots have to adjust and control these computers constantly to keep the aircraft airborn and everyone safe. Coming into land even on an 'autopilot mode' .. synched with an ILS approach (think of it as a radio frequency guiding your X and Y position (or vertical and horizontal position in space as you follow the G/S) -- You still must maintain appropriate engine speeds, thrust percentage, blade N1, N2 etc, Flaps, auto spoilers.. Auto brake levels,.. and the ultimate landing is by human hands on the yoke.. (Or joystick in airbus, etc). The last "minimums" 200ft or less or so you take over and flare and adjust several things to touch down at an appropriate vertical descent rate and so on.. Point is -- if you carry that 'simulator' and learn it well.. it will give you a huge edge on understanding how to fly the real