To own and operate an aircraft, a pilot has to have an aviation license. There are a number of eligibility requirements that must be met before someone can attend flight school. Depending on the aspiring pilot's goal, he might settle for a sport aviation license, a private aviation license, or he might continue to work toward a commercial aviation license. In order to be eligible to get a private aviation license, the student must be at least 17. If the student is interested in flying lighter-than-air aircraft like gliders or balloons, the age is 14. The student must also be able to read, speak, and understand English, because this is the language all control towers use to communicate with pilots. In addition, flight school costs several thousand dollars to attend (usually around $7000 total). The ground school should last about 3-5 weeks, and then the student pilot will take a written test and get some airtime with a licensed instructor. To be eligible for a higher aviation license, the student has to meet the requirements for each one, which includes an extensive amount of flight time, including cross-country and solo flight.