How to quickly have medium aircraft at your airport!
Step 1: load up an airport on easy mode (2,000,000 starter cash)
Step 2: hit F10 and turn off simulate construction
Step 3: expand the map by purchasing the top left land box
Step 4: place a runway, expand it to 800 meters, and set it to asphalt
Step 5: place the runway entrance/exits and connect them with taxiway
Step 6: map out space to later add a deicing pad for the aircraft
Step 7: place out 4 gates in a row after the space from Step 6
Step 8: create the bottom floor (the space is 11x8)
Step 9: build the second floor (the long strip if from the start of the first gate all the way to 1 block after the Jetway of the last gate so its 4x33)
Step 10: place the boarding desks and open the gates
Step 11: hire staff (security, passenger service, executives)
Step 12: prepare a service vehicle area and get 4 pushback trucks (optional: assign them to a gate)
Step 13: get small control tower, open the runway, gates, and airport (if not already done)
Step 14: Get some airline contracts and set the auto planer to on, the airport can take it.
And you are done! congrats you have created an airport completely skipping small aircraft!
I recommend that after its built you save for night flights first to make more money because at night you lose lots of money!