Worry or Lack of Interest  Physical Discomfort, Illness, Fatigue, and Dehydration  Fatigue  2-13  Worry or lack of interest has a detrimental effect on learning. Learners who are worried or emotionally upset are not ready to learn  and derive little benefit from instruction. Worry or distraction may be due to learner concerns about progress in the training course, or  may stem from circumstances completely unrelated to their instruction. Significant emotional upsets may be due to personal  problems, emotional problems, or a dislike of the training program or the instructor.  The experiences of learners outside their training activities affect behavior and performance in training; the two cannot be separated.  When learners begin flight training, they bring with them their interests, enthusiasms, fears, and troubles. The instructor cannot be  responsible for these outside diversions, but cannot ignore them because they have a critical effect on the learning process. Instruction  should be keyed to the utilization of the interests and enthusiasm learners bring with them, and to diverting their attention from their  worries and troubles to learning the tasks at hand. This is admittedly difficult, but needs to be accomplished if learning is to proceed  at a normal rate.  Worries and emotional upsets that result from a flight training course can be identified and addressed. These problems are often due  to inadequacies of the course or of the instructor. The most effective cure is prevention. The instructor should be alert and ensure the  learners understand the objectives of each step of their training, and that they know at the completion of each lesson exactly how well  they have progressed and what deficiencies are apparent. Discouragement and emotional upsets are rare when learners feel that  nothing is being withheld from them or is being neglected in their training.  Physical discomfort, illness, and fatigue will slow the rate of learning during both classroom instruction and flight training. Learners  who are not completely at ease, and whose attention is diverted by discomforts such as the extremes of temperature, poor ventilation,  inadequate lighting, or noise and confusion, cannot learn at a normal rate. This is true no matter how diligently they attempt to apply  themselves to the learning task.  A minor illness such as a cold, or a major illness or injury interferes with the normal rate of learning. This is especially important for  flight instruction. Most illnesses adversely affect the acuteness of vision, hearing, and feeling, all of which are essential to correct  performance.  Airsickness can be a great deterrent to flight instruction. A learner who is airsick or bothered with incipient airsickness is incapable of  learning at a normal rate. There is no sure cure for airsickness, but resistance or immunity usually can be developed in a relatively  short period of time. An instructional flight should be terminated as soon as incipient sickness is experienced. As the learner develops  immunity, flights can be increased in length until normal flight periods are practicable.  Keeping learners interested and occupied during flight is a deterrent to airsickness. They are much less apt to become airsick while  operating the controls themselves. Blowing fresh air across the face also helps reduce symptoms of incipient sickness. Rough air and  unexpected abrupt maneuvers tend to increase the chances of airsickness. Tension and apprehension contribute to airsickness and  should be avoided.  Fatigue is one of the most treacherous hazards to flight safety as it may not be apparent to a pilot until serious errors are made.  Fatigue can be either acute (short-term) or chronic (long-term). Acute fatigue, a normal occurrence of everyday living, is the tiredness  felt after long periods of physical and mental strain, including strenuous muscular effort, immobility, heavy mental workload, strong  emotional pressure, monotony, or lack of sleep.  Acute fatigue caused by training operations may be physical or mental, or both. It is not necessarily a function of physical strength or  mental acuity. The amount of training any learner can absorb without incurring debilitating fatigue varies. Generally speaking,  complex operations tend to induce fatigue more rapidly than simpler procedures do, regardless of the physical effort involved.  Fatigue is the primary consideration in determining the length and frequency of flight instruction periods and flight instruction should  be continued only as long as the learner is alert, receptive to instruction, and is performing at a level consistent with experience.  It is important for a  flight instructor $_{ }$to be able to detect fatigue, both in assessing a learner’s substandard performance early in a  lesson, and also in recognizing the deterioration of performance. If fatigue occurs as a result of application to a learning task, the  learner should be given a break in instruction and practice.  A  flight instructor who is familiar with the signs indicative to acute fatigue will be more aware if the learner is  experiencing them. The deficiencies listed below are apparent to others before the individual notices any physical signs of fatigue. 