Above what altitude does the holding leg time increase to 1.5 minutes?

The holding leg time increases to 1.5 minutes at an altitude above 14,000 feet MSL. This adjustment is made to account for the increased distance traveled and the potential for air traffic in higher altitude airspace. As altitude increases, the aircraft's speed also typically increases due to reduced air density, meaning that the time spent on the holding leg must be adjusted longer to maintain appropriate spacing and separation in the holding pattern. Therefore, at altitudes above 14,000 feet, the prescribed holding time is extended to ensure effective management of incoming and outgoing air traffic while maintaining safety and efficiency.