The present study did not provide decisive evidence for a decrease in flight performance during exposure to simulated altitudes of 3048 and 4572 m. However, large interindividual variation in pilots' flight performance combined with a gradual decrease in alertness levels observed in the present study puts into question the ability of pilots to safely fly an aircraft while exposed to these altitudes without supplemental oxygen.Steinman Y, van den Oord MHAH, Frings-Dresen MHW, Sluiter JK. Flight performance during exposure to acute hypobaric hypoxia. Aerosp Med Hum Perform. 2017; 88(8):760-767.

INTRODUCTION: A flight is composed of many flight performance aspects. However, not all of these aspects are equally important for the success and safety of a flight. When investigating the influence of a stressor on flight performance, it is important to understand not only which flight performance aspects are important for the success and the safety of the flight, but also which of these aspects will most likely be affected by reduced alertness.METHOD: A total of 136 helicopter pilots of the Royal Netherlands Air Force (RNLAF) of all qualification levels were invited to participate in a three-round ranking Delphi study.RESULTS: A total of 41 (30%) helicopter pilots completed the first questionnaire round and 20 (77%) flight instructors completed the ranking round. The top ten skills elements comprised seven nontechnical skills (NTS), namely, awareness of the environment, decision making, workload management, stress management, planning and coordinating, general knowledge, and basic fitness; and three technical skills (TS), that is, advanced aircraft handling, flight maneuvers and procedures, and abnormal and emergency procedures. The top three ranked skill elements (awareness of environment, decision making, and workload management) were considered by the flight instructors to be highly influenced by reduced pilot alertness.CONCLUSION: NTS are considered more important and more affected by reduced pilot alertness during operational helicopter flight compared to TS.Steinman Y, van den Oord MHAH, Frings-Dresen MHW, Sluiter JK. Flight performance aspects during military helicopter flights. Aerosp Med Hum Perform. 2019; 90(4):389–395.

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The purpose of the present study was to determine how hypoxia effects awareness of environment (AoE) in helicopter pilots operating at high altitude. Eight helicopter crews flew two operational flights in a flight simulator while breathing gas mixtures of 20.9% (equivalent to 0 m altitude) and 11.4% (equivalent to 4572 m or 15,000 ft altitude) oxygen in a single blinded, counterbalanced, repeated measures study. Each flight included five missions, during which environment items were introduced that the crews needed to be aware of, and respond to. In the 4572 m simulation, the crews missed overall 28 AoE items compared to 12 in the 0 m simulation (Z ¼ À1.992; p ¼ .046). In contrast, the crews' technical skills were not significantly effected by hypoxia. Remarkably, the majority of pilots did not notice they were hypoxic or recognise their hypoxia symptoms during the simulation flight at 4572 m.Practitioner summary We show that hypoxia has a detrimental effect on helicopter pilot's AoE and alertness. This can lead to an increased risk for flight safety. To mitigate this risk we recommend performing hypoxia training in a flight simulator, developing wearable systems for physiological monitoring of pilots and re-evaluating current altitude regulations.