The emergency situation during flight causes the typical stress reactions for flight crew and passengers due to its sudden onset, urgent risk for life, long duration, sophisticated counteract and abrupt workload increase. However, the probabilistic risk is theoretically assessed on its designing stage. The detereoration of mental and behavioral pattern under emergency is categorized as the results of investigations of bailed-out accidents of fighter aircraft. Also, the reliability of behavior in critical situation is discussed in comparison with data obtained from nuclear plant operators. Voice analysis of communication and heart rate variability are the useful indicators to estimate the grades of stress reaction during flight. Tree different levels of human information processing should be considered in the emergency training for flight crew. Crew coordination is also the essential factor in emergency situation.