Taiwan 's AIC then examined TransAsia 's pilots ' roster time and flight times . From May to July 2014 , more than half of TransAsia Airways pilots had accrued over 270 flying hours . Their number was significantly higher compared to the peak summer season in 2013 , in which only 27 % of the pilots accrued over 270 flying hours . The number of daily sectors flown had also increased to a maximum of 8 , which many crew found exhausting . Most of the pilots interviewed by investigators agreed that most violations of the Standard Operating Procedures occurred when they felt fatigued , particularly when they operated a flight later in the day . The pilots protested on several occasions , but the management of TransAsia Airways apparently ignored the complaints . It did not even conduct a safety risk assessment on the matter . There have been many plane crashes involving pilot fatigue , one of the most famous occurring in the United States in 2009 when Colgan Air Flight 3407 crashed into a house in Buffalo , New York , and the deadliest occurring in 1997 when Korean Air Flight 801 crashed into Nimitz Hill in Asan , Guam . The AIC then examined if Captain Lee was fatigued at the time of the accident . If he was , then this could explain why he intentionally deviated the aircraft from its approach course . Investigators found out that Lee was not intoxicated and was also not affected either by medication or by physical health problems . The investigators could not determine if the pilots had acquired enough sleep before the flight , as they could not retrieve the data of the total hours of sleep the crew had taken before the flight . The examination of the System of Aircrew Fatigue Evaluation ( SAFE ) of the Flight 222 crew revealed that Captain Lee felt a little tired , but that First Officer Chiang was not fatigued at all . This was evidenced by Captain Lee 's yawning , which could be heard in the CVR . He also stated that he was very tired . It was revealed that several incorrect actions from Captain Lee to the tower had occurred during the flight
Colgan Air Flight 3407
Colgan Air Flight 3407
TransAsia Airways Flight 222