The pilot is the flight instructor or teacher who teaches students how to fly an aircraft.
The pilot is responsible for obtaining authorization and clearances from an appropriate authority for a prospective student before allowing her or him to fly an aircraft.
This includes obtaining written medical approval, completing flight training, and gaining ratings.
The pilot is also responsible for ensuring that the airplane is suitable for flight.
The pilot is also responsible for ensuring that the pilot is appropriately qualified, equipped, and that the airplane is airworthy.
The pilot is also responsible for understanding the limitations of the aircraft, which can be found in the pilot operating handbook (POH), and ensuring that all passengers understand these limitations.