Which indicators can a Certified Flight Instructor (CFI) use to detect fatigue in a learner?

The correct answer identifies loss of accuracy and irritability as key indicators a Certified Flight Instructor (CFI) can observe to detect fatigue in a learner. When individuals are fatigued, their physical and cognitive functions may degrade, leading to a decrease in the precision of their performance, which manifests as a loss of accuracy in tasks. This reduced capability can also provoke feelings of frustration or irritability, making it easier for an instructor to recognize that the learner may be fatigued.

In aviation training, maintaining a high level of alertness and focus is essential for both safety and effective learning. Therefore, recognizing such indicators is crucial for a CFI, as they help in making decisions about whether to continue training or implement rest periods to enhance learning outcomes and ensure safety.