The airline transport pilot licence (ATPL), or in the United States of America, an airline transport pilot (ATP) certificate is the highest level of aircraft pilot certificate. In the United States, those certified as airline transport pilots (unconditional) are authorized to act as pilot in command on scheduled air carriers' aircraft under CFR 14 Part 121. In the UK, pilots must hold an ATPL before they can be pilot in command on an aircraft with nine or more passenger seats. Context Any pilot operating an aircraft for pay must start by obtaining a commercial pilot licence (CPL). Airline transport pilot certifications do not have special endorsements, such as an instrument rating, as airline transport pilots must already possess knowledge and training in these areas. However, aircraft heavier than 12,500 pounds still require pilots to have a "type rating" (specific to the make and model of aircraft) certification. Theoretical examination EASA The EASA ATPL requires candidates to pass fourteen separate theoretical exams, with a six-month residential or twelve-month distance-learning course mandatory during this phase. In European Union Aviation Safety Agency (EASA) states and the United Kingdom, the 14 theoretical subjects included in the examination of ATPL applicants are: Air law Aircraft General Knowledge — Airframe/Systems/Power plant Instrumentation Mass and Balance Performance Flight Planning and Monitoring Human Performance Meteorology General navigation Radio navigation Operational Procedures Principles of Flight IFR Communications VFR Communications All exams must be passed within an 18-month period. A CPL and/or Instrument Rating must then be gained within 36 months. Provided that a CPL and IR are achieved, ATPL examination results are accepted for seven years after the most recent validity date of the IR entered in the CPL. ATPL exams are acceptable for the issue of a CPL, so most pilots skip the CPL exams and take their ATPL exams before they obtain their CPL. United States of America The FAA ATP certificate requires one theoretical knowledge test covering the required knowledge areas. A $5,000 ATP CTP (Airline Transport Pilot Certification Training Program, usually paid for by a hiring airline) course is required but this alone does not prepare an applicant for the knowledge test. Several weeks of additional self-study using training software is required for a realistic chance of passing the test. Eligibility EASA An applicant for an ATPL must hold a CPL(A) and a multi-engine IR for airplanes. The applicant shall also have received instruction in