The human body's response to stress is often referred to as the "fight or flight" reaction, which readies the body for defensive action or escape. This response involves various physiological changes initiated by the sympathetic nervous system, such as heightened breathing and heart rate, dilation of blood vessels in the muscles, and the release of energy stores. These changes can enhance physical strength, however they may also impair mental performance.

In the specific scenario outlined in the question, the crew experiences a sudden and unexpected loud noise from one engine during a base turn. This event is subconsciously perceived as a potential threat or danger, prompting a fight or flight response as a natural response to the situation.

Further information:
GENERAL ADAPTATION SYNDROME (GAS)

The biological reaction to stress, which the organism is mobilized by is the General Adaptation Syndrome, where adaptation means the tendency of the body to fight to restore homeostasis against forces that upset the body’s natural balance. There are three stages: alarm, resistance, and exhaustion.

• Alarm – The alarm reaction stage refers to the initial symptoms the body experiences when under stress. You may be familiar with the “fight-or-flight” response, which is a physiological response to stress. This natural reaction prepares you to either flee or protect yourself in dangerous situations. Stress hormones (adrenalin) will cause a massive release of glucose into the blood, and an acceleration of pulse and blood pressure and an increase in the rate and depth of breathing. However, no specific organ is affected.
• Resistance – The stress response is channeled into the specific organ system or process most capable of dealing with or suppressing it. During this stage, a different stress hormone cortisol (cortisone) is released which assists the body to quickly convert fats to sugar to prolong the mobilization of energy in the body. If an individual is exposed to stress for too long, his/her energy resources become depleted.
• Exhaustion – This stage is the result of prolonged or chronic stress. The organs or process dealing with the stressor break down and we return to the generalized format of the alarm phase. This needs time to get rid of the waste products created by the above processes.