What is UNLK on Airbus A320? (Unlock)

The Airbus A320 is a widely popular commercial aircraft known for its efficiency and advanced technology. One of the key features of the A320 that sets it apart from other aircraft is the Unlock system, often referred to as UNLK. Unlock is an important component of the A320’s flight control system, providing pilots with increased control and safety during flight. In this article, we will explore what Unlock is, how it works, and its significance in the aviation industry.

Understanding Unlock on the Airbus A320

Unlock, or UNLK, on the Airbus A320 refers to the flight control surface logic that enables pilots to override certain flight control protections under specific conditions. Essentially, it is a safety measure that allows pilots to manually intervene in the aircraft’s control systems if necessary. Unlock provides additional flexibility to the pilot and is designed to ensure the safety of the aircraft and its occupants.

The Unlock system is primarily activated during abnormal flight conditions or in case of system failures. By engaging the Unlock function, pilots can regain control over the aircraft’s flight control surfaces, such as the ailerons, elevators, and rudder. This capability can prove crucial in emergency situations where the autopilot or other automated systems may not be able to adequately respond.

When the Unlock system is activated, the flight control protections are temporarily relaxed, allowing the pilot to manually override the computer’s commands and make the necessary corrections. This ability to bypass certain flight control restrictions can be essential in circumstances where quick and decisive action is required.

The Importance of Unlock in Aviation Safety

Unlock plays a crucial role in maintaining the safety and control of the Airbus A320. By providing pilots with the ability to override certain flight control protections, Unlock ensures that they have the necessary tools to respond effectively to unexpected situations and system malfunctions. This feature is especially valuable in critical phases of flight, such as takeoff and landing, where precise control is essential.

During normal operations, the Airbus A320’s flight control laws actively prevent the aircraft from exceeding its limits and entering potentially dangerous flight regimes. However, there are scenarios where the intervention of the Unlock system becomes necessary. For example, if the autopilot malfunctions or if the aircraft encounters severe turbulence, the pilot may need to take manual control to ensure the safety of the flight.

Additionally, Unlock is vital in situations where additional control input is required to recover from an abnormal flight condition. The system allows pilots to override flight control restrictions and make corrective actions promptly. By doing so, they can mitigate the effects of adverse situations and regain stability, ultimately enhancing the safety of the aircraft and its occupants.

How Unlock Works – The Technical Aspect

To understand how Unlock works on the Airbus A320, it is essential to delve into the technical details. The Unlock system is part of the aircraft’s flight control laws, which consist of several modes or protections. These modes regulate the behavior of the flight control surfaces to maintain the aircraft within safe operating limits.

During normal operations of the Airbus A320, the flight control laws operate in what is referred to as “Normal Law.” In this mode, the system provides various protections to the pilot, preventing the aircraft from entering dangerous flight regimes. These protections include bank angle protection, pitch protection, and load factor limitation.

However, when certain conditions are met, such as system failures or abnormal flight conditions, the Unlock system is activated, transitioning the flight control laws into “Alternate Law.” In Alternate Law, some of the standard protections are relaxed, allowing the pilot to take direct control of the aircraft’s flight control surfaces.

It’s important to note that Alternate Law differs from Normal Law in terms of certain flight control functions and protections. For example, in Alternate Law, the bank angle protection is reduced, allowing the pilot to execute steeper turns. The load factor limitation is also relaxed, giving the pilot more flexibility in maneuvering the aircraft.

The activation of Alternate Law and the Unlock system is indicated to the pilot through various cockpit displays and alerts. When the system transitions into Alternate Law, the flight control computers generate appropriate warnings and indications to ensure the pilot is aware of the change and can respond accordingly.

The Advancements in Unlock Technology

As technology continues to advance, the Unlock system on the Airbus A320 has also seen significant improvements. Aircraft manufacturers, including Airbus, constantly strive to enhance the safety and operational capabilities of their aircraft.

Modern versions of the Unlock system incorporate sophisticated features and algorithms that provide pilots with an even greater degree of control and safety. These advancements include improved flight envelope protections, refined control surface logic, and enhanced alerting systems to inform pilots of changes in flight control law status.

With each iteration of the Airbus A320 and its flight control systems, the Unlock functionality is fine-tuned and made more intuitive for pilots. This ongoing development ensures that pilots can respond more effectively to emergencies and maintain the highest standards of safety.


Unlock on the Airbus A320 is a critical feature that empowers pilots to take control of the aircraft’s flight control surfaces in emergency situations or system failures. By allowing pilots to bypass certain flight control restrictions, Unlock ensures their ability to respond effectively and safely. This system, along with the advanced flight control laws of the A320, provides a comprehensive and robust safety net for pilots, enhancing the overall safety of the aircraft and its passengers.

The continuous advancements in Unlock technology further strengthen its capabilities, ensuring that pilots have the most advanced tools at their disposal. As the aviation industry progresses, the Unlock system will undoubtedly continue to evolve, further enhancing the safety and efficiency of the Airbus A320 and other modern aircraft.

External Link: Learn more about the Airbus A320

For More: What is MDA on Airbus A320? (Minimum Descent Altitude)