FL270 refers to a flight level of 27,000 feet above sea level, commonly used in aviation. Flight levels are standardized altitudes that help pilots maintain safe vertical separation from other aircraft. FL270 is often used for cruising in commercial airliners and is part of the standard altimeter setting in aviation. At FL270, aircraft typically operate in the lower portion of the jet stream, which can influence fuel efficiency and flight time. Pilots must adhere to air traffic control instructions to ensure safe navigation and avoid potential conflicts with other flights at similar altitudes.