has established a strong presence in all types of aviation as a means of managing error and reducing the possibility of risk. Checklists are highly regulated and consist of protocols and procedures for the majority of the actions required during a flight. The objectives of checklists include "memory recall, standardization and regulation of processes or methodologies." The use of checklists in aviation has become an industry standard practice, and the completion of checklists from memory is considered a violation of protocol and pilot error. Studies have shown that increased errors in judgement and cognitive function of the brain, along with changes in memory function are a few of the effects of stress and fatigue. Both of these are inevitable human factors encountered in the commercial aviation industry. The use of checklists in emergency situations also contributes to troubleshooting and reverse examining the chain of events which may have led to the particular incident or crash. Apart from checklists issued by regulatory bodies such as the FAA or ICAO, or checklists made by aircraft manufacturers, pilots also have personal qualitative checklists aimed to ensure their fitness and ability to fly the aircraft. An example is the IM SAFE checklist (illness, medication, stress, alcohol, fatigue/food, emotion) and a number of other qualitative assessments which pilots may perform before or during a flight to ensure the safety of the aircraft and passengers. These checklists, along with a number of other redundancies integrated into most modern aircraft operation systems, ensure the pilot remains vigilant, and in turn, aims to reduce the risk of pilot error. Notable examples One of the most famous examples of an aircraft disaster that was attributed to pilot error was the night-time crash of Eastern Air Lines Flight 401 near Miami, Florida on 29 December 1972. The captain, first officer, and flight engineer had become fixated on a faulty landing gear light and had failed to realize that one of the crew had accidentally bumped the flight controls, altering the autopilot settings from level flight to a slow descent. Told by ATC to hold over a sparsely populated area away from the airport while they dealt with the problem (with, as a result, very few lights visible on the ground to act as an external reference), the distracted flight crew did not notice the plane losing height and the aircraft eventually struck the ground in the Everglades, killing 101 of