While automatic pilot systems, also known as autopilot, offer numerous benefits for commercial flights, there are also some disadvantages and reasons why airlines don’t use it all the time. Here are a few considerations:

1. Lack of situational awareness: Autopilot systems are designed to follow pre-programmed flight plans and maintain the desired altitude, heading, and speed. However, they do not possess the same level of situational awareness as human pilots. They are unable to interpret and respond to dynamic and unpredictable events in the same way as a human pilot can. Therefore, human pilots are essential for monitoring the overall flight operation and making critical decisions based on real-time information.
2. System limitations and failures: Autopilot systems are complex and sophisticated, but they can still experience malfunctions or encounter situations outside their operational limits. In such cases, the human pilots must be prepared to take control of the aircraft and handle the situation manually. The ability of pilots to actively fly the aircraft is crucial for responding to unexpected events or technical failures.
3. Adapting to changing conditions: Autopilot systems may struggle to adapt to rapidly changing weather conditions, air traffic situations, or deviations from the planned route. Human pilots possess the ability to assess the situation, communicate with air traffic control, and adjust the flight path or altitude as necessary.
4. Pilot proficiency and training: Continuous training and proficiency are essential for pilots to maintain their skills and ability to manually fly the aircraft. Relying solely on autopilot systems could potentially lead to degradation of pilot skills, which may impact their ability to handle manual flying in case of emergencies or unusual situations.
5. Safety and redundancy: The presence of human pilots provides an additional layer of safety and redundancy. They can cross-check the performance of the autopilot system, monitor critical flight parameters, and intervene when necessary. Having human pilots in the cockpit ensures that there are trained professionals ready to handle any unexpected situations or emergencies that may arise during the flight.

It’s important to note that autopilot systems are widely used in commercial aviation and play a significant role in maintaining flight efficiency, stability, and accuracy. They help reduce pilot workload, ensure precise navigation, and contribute to fuel savings. However, human pilots remain essential for overseeing the flight operation, making critical decisions, and ensuring the overall safety of the flight.