What are Airbus Flight Control laws?

Airbus is a leading manufacturer of commercial aircraft known for their innovative and advanced designs. One aspect of Airbus aircraft that sets them apart is their flight control laws, which are the sets of rules and procedures that govern how the aircraft responds to pilot inputs and various flight conditions. There are four primary flight control laws that Airbus aircraft utilize: normal, alternate, abnormal alternate, and direct. Understanding these flight control laws is important for pilots and aircraft maintenance technicians to ensure the safe and efficient operation of Airbus aircraft.

Normal flight control law is the default mode of operation for Airbus aircraft and is used during all phases of flight, except during certain failure conditions. In normal flight control law, the aircraft's flight control system (FCS) is fully operational and able to provide automatic control of the aircraft's pitch, roll, and yaw through the use of hydraulic actuators. The FCS also monitors the aircraft's speed, altitude, and attitude to ensure that it is within predetermined limits. If the aircraft exceeds these limits, the FCS will automatically make corrections to bring the aircraft back within limits.

Alternate flight control law is activated when a failure occurs in the FCS that affects its ability to control the aircraft. When alternate flight control law is engaged, the aircraft's FCS switches to a backup mode of operation that uses different sensors and control surfaces to maintain control of the aircraft. In alternate flight control law, the FCS may not be able to provide the same level of automatic control as it does in normal flight control law, so the pilot must be prepared to manually control the aircraft using the primary flight controls.

Abnormal alternate flight control law is a further degraded mode of operation that is activated when a failure occurs in both the primary and backup FCS. In abnormal alternate flight control law, the aircraft's FCS is unable to provide any automatic control and the pilot must rely solely on the primary flight controls to manually fly the aircraft. This mode of operation is only intended as a temporary measure and the pilot must take steps to land the aircraft as soon as possible.

Direct flight control law is a special mode of operation that is activated when the FCS is unable to provide any control of the aircraft's flight surfaces. In direct flight control law, the pilot's inputs to the primary flight controls are directly transmitted to the aircraft's flight surfaces, bypassing the FCS completely. This mode of operation is extremely rare and is only used in the most severe failure conditions.

In addition to the four primary flight control laws, Airbus aircraft also have a mechanical backup system that can be used to control the aircraft in the event of a complete failure of the flight control system. The mechanical backup system is a manual system that uses cables and pulleys to connect the pilot's inputs on the primary flight controls to the aircraft's flight surfaces. The mechanical backup system is only intended as a last resort, and the pilot must be physically strong enough to use it to control the aircraft. The mechanical backup system is not as precise or responsive as the aircraft's normal flight control system, and the pilot must use a greater amount of force on the primary flight controls to achieve the desired control inputs. It is important for pilots to be familiar with the operation of the mechanical backup system and to practice using it in a simulator before attempting to use it in an actual emergency situation.

In addition to the mechanical backup system, Airbus aircraft also have additional modes of operation that are activated in specific failure conditions, such as landing gear failure or engine failure. It is important for pilots and aircraft maintenance technicians to be familiar with all of these modes of operation and how to transition between them in order to ensure the safe operation of Airbus aircraft.

Overall, the flight control laws of Airbus aircraft are designed to provide a high level of safety and reliability. The normal, alternate, abnormal alternate, and direct flight control laws are essential to the operation of Airbus aircraft and allow pilots to safely and effectively respond to a wide range of failure conditions.