Four-engine aircraft are airplanes equipped with four engines, which can be either jet engines or propellers. These aircraft are designed for long-distance travel and can carry large numbers of passengers or cargo. The additional engines provide increased power and redundancy, enhancing safety and performance, especially during takeoff and landing. Common examples of four-engine aircraft include the Boeing 747 and the Airbus A380. These planes are often used for international flights and can operate in various weather conditions. Their design allows for greater fuel efficiency and the ability to fly longer distances without needing to refuel.