Arousal is “the measure of the human being’s readiness to respond”. Arousal can manifest in various ways, including increased heart rate, heightened awareness, increased muscle tension, and a heightened state of consciousness.

High vigilance is a state of sustained attention, alertness, and watchfulness for the detection of specific events, stimuli, or changes in the environment. It involves maintaining a heightened state of awareness over an extended period of time to identify and respond to rare or unexpected occurrences or potential threats. The state of vigilance is the degree of activation of the central nervous system. This can vary from deep sleep to extreme alertness and is controlled by the circadian cycle.

A long-haul North Atlantic flight is generally calm and uneventful. During the cruise phase of such flights, when there are fewer critical tasks to perform, stress and arousal levels for pilots tend to be lower compared to more active phases like takeoff and landing. However, maintaining vigilance is crucial to monitor the aircraft systems, weather conditions, and any potential changes or emergencies that may occur during the flight.