What is NNC in Aviation? (Non-Normal Checklist)

In aviation, safety is of utmost importance. Pilots and flight crews are trained to handle a wide range of situations that may occur during a flight, including both normal and non-normal circumstances. When faced with an abnormal situation, pilots rely on their knowledge and expertise to diagnose and resolve the issue. One tool they use to guide them through these situations is a non-normal checklist.

A non-normal checklist, also known as an NNC, is a set of procedures specifically designed to address atypical situations that may arise during the course of a flight. These checklists provide step-by-step instructions for the crew to follow in order to resolve the issue safely. While normal checklists are primarily focused on routine procedures, such as pre-flight and in-flight checks, non-normal checklists are used when something goes wrong.

Non-normal checklists cover a wide range of possible scenarios, from minor malfunctions to major emergencies. These checklists are meticulously developed by aviation experts and are based on extensive research, manufacturer recommendations, and regulatory requirements. They are designed to guide the crew in carrying out necessary actions and decisions systematically, ensuring that they cover all critical steps and avoid missing anything important.

During flight training, pilots learn to use both normal and non-normal checklists effectively. They are taught to identify and differentiate between normal and non-normal situations so they can select the appropriate checklist to follow. A non-normal checklist is typically divided into several sections, each addressing a specific type of abnormal situation. This division allows the crew to quickly locate the relevant checklist and efficiently address the issue.

Non-normal checklists are an essential tool in aviation safety. They provide pilots and flight crews with clear guidance during abnormal situations, ensuring they take the necessary actions to resolve the problem. By following the checklist, the crew can minimize the risk of errors and maintain a structured approach to problem-solving.

The Importance of Non-Normal Checklists

Non-normal checklists play a crucial role in aviation safety by helping pilots and flight crews manage abnormal situations effectively. Here are some key reasons why these checklists are essential:

The Complexity of Abnormal Situations

When an abnormal situation occurs during a flight, the cockpit environment becomes more challenging, with increased workload and time pressure. In such situations, pilots need clear and concise guidance to aid their decision-making process. Non-normal checklists provide precisely that. They outline the necessary steps to be taken, ensuring pilots do not miss critical actions in the midst of a high-pressure situation. These checklists simplify complex procedures by breaking them down into manageable steps, thus allowing pilots to focus on resolving the issue.

The Reduction of Human Error

Human error is a significant factor in aviation accidents and incidents. During abnormal situations, the presence of stress, anxiety, and time pressure can further increase the likelihood of errors. Non-normal checklists serve as a reliable tool for pilots and flight crews to minimize the risk of human error. By following the checklist instructions precisely, they can maintain a structured approach, reducing the chance of overlooking crucial steps or making incorrect decisions under pressure.

Consistency in Response

Non-normal checklists promote consistency in response across different flights and crews. By adhering to established procedures, pilots and flight crews ensure that the same approach is taken regardless of who is flying the aircraft. This consistency is important for maintaining safety and efficiency, as it allows for a seamless transition between different crew members during a flight or across various flights. It also ensures that critical steps are not missed or overlooked, further enhancing the overall safety of aviation operations.

Creating a Non-Normal Checklist

The development of non-normal checklists involves a rigorous process to ensure their effectiveness and reliability. Here are the key steps involved in creating a non-normal checklist:

Identifying Non-Normal Scenarios

The first step in creating a non-normal checklist is to identify potential abnormal situations that may occur during flight. This can be achieved through a thorough analysis of historical data, incident reports, and manufacturer recommendations. Aviation authorities and regulatory bodies also play a role in identifying and categorizing different types of abnormal situations that need to be addressed in a checklist.

Research and Expert Guidance

Once the non-normal scenarios are identified, extensive research is conducted to gather relevant information and expert guidance. This research involves studying aircraft manufacturer documentation, system manuals, and industry best practices. Aviation experts, including pilots and engineers, are consulted for their expertise and insights in order to develop comprehensive checklists that cover all critical steps and procedures.

Review and Approval

After the creation of the initial draft, the non-normal checklist undergoes a rigorous review process. This involves scrutiny by aviation experts, regulatory authorities, and pilot representatives. Any necessary revisions or additions are made based on their feedback and recommendations. Once the checklist is deemed satisfactory, it is officially approved for use by the relevant authorities or organizations.


Non-normal checklists are an integral part of aviation safety. They provide pilots and flight crews with clear and concise guidance during abnormal situations, enabling them to respond effectively and resolve the issue at hand. These checklists help streamline decision-making, reduce the risk of human error, and maintain consistency in response across different flights and crews. Through a meticulous development process, non-normal checklists are created to cover a wide range of potential abnormal scenarios, ensuring that pilots have the necessary tools to handle any situation that may arise during a flight.

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