The 1500-hour rule is a federal regulation in the United States (established under the Airline Safety and Federal Aviation Administration Extension Act of 2010) that requires most pilots to accumulate a minimum of 1,500 flight hours before they can obtain an Airline Transport Pilot (ATP) certificate. This certificate is a prerequisite for serving as a first officer or captain for a Part 121 commercial airline. The rule was designed to improve safety by ensuring that pilots have significant "real world" experience before entering a commercial cockpit. There are, however, "Restricted ATP" (R-ATP) exceptions: graduates of approved four-year aviation degree programs can qualify at 1,000 hours, two-year graduates at 1,250 hours, and former military pilots at 750 hours. The 1,500 total hours must also include specific sub-requirements, such as 500 hours of cross-country time, 100 hours of night flight, and 75 hours of instrument time. In 2026, this rule remains a cornerstone of US aviation safety policy, although it is frequently debated as a contributing factor to the ongoing pilot shortage and the high cost of entry into the profession.