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The Physical Environment and the Physiology of Flight
Published in Harry W. Orlady, Linda M. Orlady, John K. Lauber, Human Factors in Multi-Crew Flight Operations, 2017
Harry W. Orlady, Linda M. Orlady, John K. Lauber
Hypoxia occurs when there is insufficient oxygen to meet tissue needs. In aviation, it is usually associated with the fall in ambient pressure that accompanies a climb to altitude. Hypoxia first affects the higher mental functions because brain tissues are most sensitive to a lack of oxygen. Hypoxic effects happen more quickly at higher altitudes. The time for useful consciousness (TUC), which is usually defined as the time in which a person can be expected to take effective preventive measures, can be as little as 40 to 74 seconds at 30,000 feet (Sells and Berry, 1961). Actual TUC varies with individuals, the aircraft altitude, the rate at which pressure falls, and the physical activity of the individual at the time of the incident.
Malaysia Airlines Flight 370
Published in Elizabeth A. Hoppe, Ethical Issues in Aviation, 2018
Mechanical failure could have led to the rapid decompression of the aircraft. In the event of cabin decompression, the pilots could have lost control of the 777, due to being victims of hypoxia. Hypoxia is a physical condition that is related to low oxygen levels in the blood stream and tissues. This condition could have led to the loss of situational awareness by the flight crew, thus leading to problematic decision-making, including the inability to react appropriately to the emergency. This scenario also seems plausible due to the alteration in the flight path of the aircraft. The Inmarsat satellite data shows that the aircraft made a complete turnaround, which could have occurred before the pilots lost control of the aircraft.
The Perfect Storm
Published in Joyce A. Hunter, Anger in the Air, 2016
Many of the effects caused by high altitude, drinking, smoking and toxic chemicals on our bodies seem to be due to a single problem—oxygen deprivation. To work properly, our brains need a certain amount of usable oxygen in our bloodstreams. Unfortunately altitude, alcohol, smoking, and toxic chemicals all reduce that usable oxygen level, which can leave passengers with a form of oxygen deprivation called “hypoxia.” The symptoms of hypoxia range from headaches, nausea, thirst, irritability, rage, sexual excitability, and loss of judgment and control to, at the extreme, seizures, paralysis, coma and death.
Integrating physiological monitoring systems in military aviation: a brief narrative review of its importance, opportunities, and risks
Published in Ergonomics, 2023
David M. Shaw, John W. Harrell
Hypoxia is a state of inadequate oxygen availability to maintain normal physiological function. The hallmark indicator of a hypoxic environment is hypoxaemia, a reduction in arterial PO2, which is typically determined by reduced peripheral blood haemoglobin-oxygen saturation (SpO2) to <88–92%. Cognition, vision, and motor-performance are impaired, particularly under severe hypoxia (e.g. exposure to >20,000 ft PO2 equivalent) (Shaw, Cabre, and Gant 2021). Hypoxia also reduces G-tolerance (Besch et al. 1994) and decreases AGSM performance due to impaired muscular performance (Millet et al. 2012). Hypoxaemia can also reduce cerebral tissue oxygenation (Ottestad, Kåsin, and Høiseth 2018; Phillips et al. 2009; Williams et al. 2019), despite an increase in cerebral blood flow (CBF) (Ainslie, Hoiland, and Bailey 2016; Hoiland et al. 2016). Ventilation increases in an attempt to elevate alveolar PO2 and consequently decreases alveolar and arterial carbon dioxide, leading to hypocapnia (see below). Heart rate (HR) increases (Botek et al. 2015; Krejčí, Botek, and McKune 2018), HR variability (HRV) decreases (Botek et al. 2015; Krejčí, Botek, and McKune 2018) and electroencephalogram (EEG) power amplitudes are altered (Rice et al. 2019). These physiological responses appear greatest with hypobaric compared with normobaric hypoxia (Coppel et al. 2015).
Exposure to hypoxia impairs helicopter pilots’ awareness of environment
Published in Ergonomics, 2021
Yuval Steinman, Eric Groen, Monique H. W. Frings-Dresen
Helicopter cabins are not pressurised and are often not equipped with oxygen systems. Therefore, hypoxia is a hazard to helicopter pilots flying at altitude. Hypoxia is a state of insufficient oxygen in the blood, tissues, and/or cells (Boshers 2015). To prevent hypoxia-related incidents there are altitude and flight duration restrictions for helicopter crews. For example, the Royal Netherlands Air Force allows their helicopter pilots to fly up to 3962 m (13,000 ft) for a maximum duration of 30 min, whereas pilots of the United States Air Force are allowed to fly 30 min at 4267 m (14,000 ft) (Command AFSO, 2017). Nonetheless, helicopter pilots have reported experiencing hypoxia symptoms even at altitudes below 3048 m (10,000 ft), where it is considered safe to fly (Haerkens and Steen 2007; Nishi 2011; Smith 2005).
Haematological responses to repeated sprints in hypoxia across different sporting modalities
Published in Research in Sports Medicine, 2021
Marta Camacho-Cardenosa, Alba Camacho-Cardenosa, Justin Kemp, Javier Brazo-Sayavera, Rafael Timon, Guillermo Olcina
Hypoxia is a state in which the body, in its entirety or specific region/s, is deprived of an adequate supply of O2. While early hypoxia research was carried out at high altitude (hypobaric hypoxia environment), many research teams seek to replicate high-altitude conditions at lower altitudes in either hypobaric or normobaric hypoxic laboratories (Coppel et al., 2015), using a decrease in PO2 (hypobaric hypoxia) or an increased fraction of nitrogen in air (normobaric hypoxia). Exposure to hypoxic conditions during exercise can lead to adaptations that compensate for the lower availability of O2: stimulation of red corpuscle (Dick, 1992), increased myoglobin content (Vogt et al., 2001), increased mitochondrial activity (Hoppeler et al., 2003) and/or increased mechanical efficiency (Morton & Cable, 2005; Schmitt et al., 2006). These training conditions can also lead to improvements in athlete performance, which are generally attributed to haematological responses to the hypoxic stimulus (Ploszczyca et al., 2018).