FL100 is a designation used in aviation to refer to a flight level of 10,000 feet above sea level. This altitude is significant for pilots and air traffic controllers as it marks a transition point in altitude management. Above FL100, aircraft typically operate under different regulations and procedures, including changes in airspace classification. At FL100, aircraft are often required to maintain a minimum vertical separation from other aircraft. This helps ensure safety in busy airspace. Additionally, flying at this altitude allows for more efficient fuel consumption and better weather avoidance strategies, as pilots can navigate above certain weather patterns.