Human Performance and Limitation PDF

2024-02-13 Human Performance and Limitation Asist. dr. A. Radzevičienė The normal working of the human body when in flight can be influenced by altitude, pressure, temperature, acceleration and changes in perception....

2024-02-13 Human Performance and Limitation Asist. dr. A. Radzevičienė The normal working of the human body when in flight can be influenced by altitude, pressure, temperature, acceleration and changes in perception. 1  2024-02-13 The atmosphere https://scied.ucar.edu/atmosphere-layers The International Standard Atmosphere (ISA) A statistic atmosheric model of how the pressure, temperature, density, and viscosity of the Earth‘s atmosphere change over a wide range of altitudes or elevations Temperature +15 ◦C Pressure 1013,25 mbs (760 mm Hg) Density 1225 g/m3 2  2024-02-13 Lapse rate Rate at which temperature changes with height in the Atmosphere (decreases as the altitude increases) The higher you are, the colder will be A lapse rate of 1.98°C/1000 ft (6.5°/km) up to 36 090 ft (11 km) thereafter the temperature remains constant at - 56.5°C up to 65 617 ft (20 km) Atmospheric pressure 3  2024-02-13 Atmospheric pressure The altitudes in the standard atmosphere that pressure will be ¼, ½ and ¾ of MSL pressure is approximately: ¼ MSL - 36 000 ft ½ MSL - 18 000 ft ¾ MSL - 8000 ft Composition of atmosphere Oxygen (O2)21% Nitrogen (N2)78% Argon (Ar) 0,93% Carbon dioxide (CO2) 0,03% Rare gases 0,04% Constant to about 70 000 ft (21 km) 4  2024-02-13 Altitude (in aviation) Altitude elevation above mean sea level Height a measure of the vertical distance of an aircraft above the airfield elevation Transition altitude (TA) the altitude above sea level at which aircraft change from the use of local barometer derived altitudes to the use of flight levels Flight level FL290 means that the aircraft altimeter indicates 29,000 ft above the standard pressure datum of 1013.2 mb Cabin altitude pressure being maintained within the aircraft cabin The physical gas laws Boyle’s Law; Dalton’s Law; Henry’s Laws; the General Gas Law. 5  2024-02-13 Boyle’s Law providing the temperature is constant, the volume of a gas is inversely proportional to its pressure. Otic and gastrointestinal tract barotrauma, aerodontalgia Dalton’s Law The total pressure of the gas mixture is equal to the sum of its partial pressure Pt = P1 + P2 + P3............ Pn Where: Pt = total pressure of the mixture P1, P2............ Pn = partial pressure of each of the constituent gases Hypoxia and night vision 6  2024-02-13 Henry’s Law At equilibrium the amount of gas dissolved in a liquid is proportional to the gas pressure Decompression sickness and “bends” Fick‘s law The rate of gas transfer is proportional to the area of the tissue and the difference between the partial pressures of the gas on the two sides and inversely proportional to the thickness of the tissue Diffusion of gas at the lungs and cells 7  2024-02-13 Charles‘ law The volume of a fixed mass of gas held at a constant pressure varies directly with the absolute temperature Where V1 = initial volume V2 = final volume T1 = initial absolute temperature = initial temperature t1°C + 273 T2 = final absolute temperature = final temperature t2°C + 273 The General Gas Law Gas equation, Combined gas law The product of the pressure and the volume of a quantity of gas divided by its absolute temperature is a constant Where p = pressure, v = volume, T = absolute temperature 8  2024-02-13 Partial Pressure Total pressure decreases as altitude increases (according Dalton‘s law) Thresholds of Oxygen Requirements Summary Altitude Oxygen requirements Up to 10 000 ft Air only 10 000 - 33 700 ft Oxygen/Air mixture 33 700 - 40 000 ft 100% Oxygen Above 40 000 ft 100% Oxygen under pressure 9  2024-02-13 Respiratory system (kvėpavimo sistema) Respiratory system (kvėpavimo sistema) Divided into two parts: Upper respiratory tract: The section that takes air in and nose lets it out mouth the beginning of the trachea Lower respiratory tract: trachea bronchi The act of breathing takes place in broncheoli this part of the system lungs 10  2024-02-13 Respiratory system (kvėpavimo sistema) Respiratory system (kvėpavimo sistema) 11  2024-02-13 Upper respiratory system (apatinė kvėpavimo sistema) The trachea (trachėja) the tube connecting the throat to the bronchi. The bronchi (bronchai) the trachea divides into two bronchi (tubes). One leads to the left lung, the other to the right lung. Inside the lungs each of the bronchi divides into smaller bronchi. The broncheoli (bronchiolės) the bronchi branches off into smaller tubes called broncheoli which end in the pulmonary alveolus. Pulmonary alveoli (plaučių alveolės) tiny sacs (air sacs) delineated by a single-layer membrane with blood capillaries at the other end. The lungs (plaučiai) a pair of organs found in all vertebrates. The act of breathing Breathing Reflex, automatic process Rate of 12 to 20 breaths/minute, averaging 16 breaths/minute Stages of breathing Inhalation Exhalation 12  2024-02-13 Breathing and CO2 The respiratory centers contain chemoreceptors detection pH levels in the blood sending signals to the respiratory centers of the brain adjusting the ventilation rate to change acidity by increasing or decreasing the removal of carbon Brainstem (smegenų kamienas) Measurement of respiratory system (kvėpavimo sistema) Air volume Lung (plaučiai) capacity Maximum lung volume is known as TLC (total lung capacity) The maximum lung volume of a healthy adult is up to 5-6 liters. Essential air volume maximum volume utilized by the lungs for inhalation, also known as VC (vital capacity) Residual Volume volume of air remaining in the lungs even after the most forceful expiration. It amounts to about 1200 ml in the normal male adult 13  2024-02-13 Measurement of respiratory system (kvėpavimo sistema) Tidal Volume volume of air inhaled and exhaled with each normal breath. It amounts to about 500 ml in the normal male adult. Inspiratory Reserve Volume extra volume of air that can be inhaled over and beyond the normal tidal volume. It amounts to about 3000 ml in the normal male adult. Expiratory Reserve Volume amount of air that can be still exhaled by forceful expiration after the end of the normal tidal expiration. It amounts to about 1100 ml in the normal male adult. Rate of airflow through the respiratory airways (into and out of the lungs).This measures the effectiveness of airflow. Efficiency of diffusion of oxygen from the pulmonary alveoli into the blood (not dealt with in this unit).. All pulmonary volumes and capacities are about 20% - 25% less in the female. External and internal respiration External respiration - the exchange of gasses between the external environment and the bloodstream Internal respiration - cellular respiration is the metabolic process by which an organism obtains energy through the reaction of oxygen with glucose 14  2024-02-13 Gas exchange between the tissues of the body and the environment Chemical reaction between oxygen and carbohydrate produces carbon dioxide Metabolism - the utilisation of oxygen and production of carbon dioxide by the tissues Functions of respiratory system Supplies the body with oxygen and disposes of carbon dioxide Filters inspired air Produces sound Contains receptors for smell Rids the body of some excess water and heat Helps regulate blood pH 15  2024-02-13 Circulatory System (Kraujotakos sistema) Cardiovascular system (Širdies ir kraujagyslių sistema) Consists of the organs and fluids that transport materials across the body. All vertebrates (stuburiniai), including humans, have a closed circulatory system, which means that blood remains within blood vessels (kraujagyslės) and does not directly interact with body tissues. 16  2024-02-13 Circulatory System (Kraujotakos sistema) The circulatory system transports blood throughout the body and, with the help of other systems in the body, it maintains favorable conditions for the cells of the body. Circulatory System (Kraujotakos sistema) contractions of the heart generate blood pressure, which moves blood through blood vessels; blood vessels transport the blood from the heart into arteries, capillaries, and veins; and blood then returns to the heart so the circuit can be completed; gas exchange (pickup of carbon dioxide waste and drop-off of oxygen for the cells) occurs at the smallest diameter vessels, the capillaries; and the heart and blood vessels regulate blood flow, according to the needs of the body. 17  2024-02-13 Circulatory System (Kraujotakos sistema) Circulatory system consists of the heart, which pumps blood, and the blood vessels, through which the blood flows The Heart (Širdis) a muscular pumping organ located medial to the lungs (plaučiai) along the body’s midline in the thoracic region (krūtinės ląstos sritis). The bottom tip of the heart, known as its apex (viršūnė), is turned to the left, so that about 2/3 of the heart is located on the body’s left side with the other 1/3 on right. The top of the heart, known as the heart’s base (širdies pagrindas), connects to the great blood vessels of the body: the aorta (aorta), vena cava (tuščioji vena), pulmonary trunk (the main pulmonary artery) (pagrindinė plaučių arterija), pulmonary veins (plaučių venos). 18  2024-02-13 Structure of the Heart Wall Epicardium Myocardium Endocardium Chambers of the Heart The heart contains 4 chambers: the right atrium (dešinysis prieširdis) receives blood from the veins and pumps it to the right ventricle left atrium (kairysis prieširdis) receives oxygenated blood from the lungs and pumps it to the left ventricle right ventricle (dešinysis skilvelis), receives blood from the right atrium and pumps it to the lungs, where it is loaded with oxygen left ventricle (kairysis skilvelis) (strongest) pumps oxygen-rich blood to the rest of the body. The left ventricle’s vigorous contractions create our blood pressure 19  2024-02-13 Valves of the Heart (Širdies vožtuvai) A system of one-way valves For preventing blood from flowing backwards Circulatory Loops (kraujo apytakos ratas) 1. The pulmonary circulation loop Pulmonary circulation transports deoxygenated blood from the right side of the heart to the lungs, where the blood picks up oxygen and returns to the left side of the heart. The pumping chambers of the heart that support the pulmonary circulation loop are the right atrium and right ventricle. 2. The systemic circulation loop. Systemic circulation carries highly oxygenated blood from the left side of the heart to all of the tissues of the body (with the exception of the heart and lungs). Systemic circulation removes wastes from body tissues and returns deoxygenated blood to the right side of the heart. The left atrium and left ventricle of the heart are the pumping chambers for the systemic circulation loop. 20  2024-02-13 Circulatory Loops (kraujo apytakos ratas) 1. The pulmonary circulation loop (mažasis kraujo apytakos ratas) 2. The systemic circulation loop (didysis kraujo apytakos ratas) Blood vessels (kraujagyslės) Major types: arteries (arterijos) capillaries (kapiliarai) Veins (venos) About 150 000 km 21  2024-02-13 Arteries (arterijos) Carry blood away from the heart Have thick walls Arteriole is a very small artery that leads to a capillary Capillaries (kapiliarai) smallest and thinnest of the blood vessels in the body connect to arterioles on one end and venules on the other 22  2024-02-13 Veins (venos) large return vessels very low blood pressure the walls thinner, less elastic, and less muscular than arteries Venules – very small veins 23  2024-02-13 Arteries and veins comparison 24  2024-02-13 Coronary arteries and veins (vainikinės arterijos ir venos) The coronary arteries are responsible for carrying nutrient-rich, oxygenated blood from the left ventricle to the myocardium; The coronary veins take nutrient – poor deoxygenated blood away from the myocardium and to the right atrium. The stages of the cardiac cycle Relaxation phase Atrial systole Ventricular systole 25  2024-02-13 Pulse Rate Factors which lead to pulse rate change (varies demand for oxygen): Exercise Altitude Temperature Factors which lead to pulse rate change (result of the sympathetic/ parasympathetic control of the heart) Fight or Flight (GAS) Syndrome Shock Emotion (fear, anxiety and anger) Pulse Rate 26  2024-02-13 Blood pressure (kraujospūdis) Blood pressure (kraujospūdis) Systolic blood pressure (the first number) – indicates how much pressure your blood is exerting against your artery walls when the heart beats. Diastolic blood pressure (the second number) – indicates how much pressure your blood is exerting against your artery walls while the heart is resting between beats. An average pilot blood pressure will rise slightly with age as the arteries lose their elasticity 27  2024-02-13 Blood pressure: hypotension and hypertension Hypotension - low blood pressure Lower 90/60 mm Hg Hypertension – high blood pressure the long-term force of the blood against artery walls is high Both hypotension and hypertension may disqualify the pilot from obtaining a medical clearance to fly Hypotension (per žemas kraujospūdis) symptoms fatigue lightheadedness dizziness nausea clammy skin depression loss of consciousness blurry vision 28  2024-02-13 Hypertension (per aukštas kraujospūdis) effects on body Can damage artery and blood vessel Osteoporosis walls over time Dementia The major factor of ‘strokes’ in the general population. Choroidopathy or bleeding in the eye Aneurysm Blurred or loss of vision Problems with memory and Arrhythmias understanding Sleep apnea Left ventricular hypertrophy Chest pain Heart attack or stroke Kidney damage or failure Heart failure Artery damage Erectile dysfunction Hardening of the arteries Vaginal dryness or lowered sexual Blood clot desire Hypertension causes Primary (essential) hypertension no identifiable cause Secondary hypertension Obstructive sleep apnea Kidney problems Adrenal gland tumors Thyroid problems Certain defects you're born with (congenital) in blood vessels Certain medications, such as birth control pills, cold remedies, decongestants, over-the-counter pain relievers and some prescription drugs Illegal drugs, such as cocaine and amphetamines 29  2024-02-13 Hypertension risk factors Age Too much salt (sodium) in Race diet Family history Too little potassium in diet Being overweight or obese Drinking too much alcohol Not being physically active Stress Using tobacco Certain chronic conditions Pregnancy (sometimes) How to Reduce Your High Blood Pressure (1) Increase activity and exercise more Lose weight if you’re overweight Cut back on sugar and refined carbohydrates (angliavandeniai) Eat more potassium (K) and less sodium (Na) Eat less processed food Stop smoking Reduce excess stress Try meditation or yoga 30  2024-02-13 How to Reduce Your High Blood Pressure (2) Eat some dark chocolate Try medicinal herbs Make sure to get good, restful sleep Eat garlic or take garlic extract supplements Eat healthy high-protein foods Take these BP-lowering supplements Drink less alcohol Consider cutting back on caffeine Take prescription medication Resting cardiac output Cardiac output (CO) (širdies minutinis tūris) is a measurement of the amount of blood pumped by each ventricle in one minute. Stroke volume (SV) (sistolinis tūris) is the amount of blood pumped by each ventricle Mean for 70 kg is 70 mL Heart rate (HR) – contractions per minute (or beats per minute, bpm). the mean CO is 5.25 L/min, For average human a range of 5.0–5.5 L/min CO = HR × SV 31  2024-02-13 Major factors influencing cardiac output https://youtu.be/CWFyxn0qDEU 32  2024-02-13 Coronary artery disease develops when the major blood vessels that supply your heart become damaged or diseased Coronary artery disease Chest pain (angina) Shortness of breath Heart attack 33  2024-02-13 Coronary artery disease causes Smoking High blood pressure High cholesterol Diabetes or insulin resistance Not being active (sedentary lifestyle) Coronary artery disease causes risk factors Age. Diabetes. Sex. Overweight or obesity. Family history. Physical inactivity. Smoking. High stress. High blood pressure. Unhealthy diet. High blood cholesterol levels. 34  2024-02-13 Coronary artery disease other possible risk factors Sleep apnea High-sensitivity C-reactive protein (hs-CRP) High triglycerides Homocysteine Preeclampsia Alcohol use Autoimmune diseases Facts about Blood (Kraujas) Approximately 8% of an adult’s body weight is made up of blood. Females have around 4-5 litres, while males have around 5-6 litres. This difference is mainly due to the differences in body size between men and women. Its mean temperature is 38 degrees Celcius. It has a pH of 7.35-7.45, making it slightly basic Whole blood is about 4.5-5.5 times as viscous (tirštesnis) as water. Blood in the arteries is a brighter red than blood in the veins because of the higher levels of oxygen found in the arteries. An artificial substitute for human blood has not been found. 35  2024-02-13 Functions of blood Transport Protection Regulation Functions of blood: Transport Gases, namely oxygen (O2) and carbon dioxide (CO2), between the lungs and rest of the body Nutrients (maisto medžiagos) from the digestive tract (virškinimo traktas) and storage sites to the rest of the body Waste products to be detoxified or removed by the liver (kepenys) and kidneys (inkstai) Hormones from the glands (liaukos) in which they are produced to their target cells Heat to the skin so as to help regulate body temperature 36  2024-02-13 Functions of blood: Protection Leukocytes, or white blood cells, destroy invading microorganisms and cancer cells Antibodies and other proteins destroy pathogenic substances Platelet (trombocitai) factors initiate blood clotting and help minimise blood loss Functions of blood: Regulation pH by interacting with acids and bases Water balance by transferring water to and from tissues 37  2024-02-13 Composition of blood Plasma Formed elements Erythrocytes (eritrocitai) Leukocytes (leukocitai) granulocytes neutrophils, eosinophils basophils agranulocytes lymphocytes monocytes Platelets (trombocitai) Erythrocytes (eritrocitai) Red blood cells Functions: To pick up oxygen from the lungs and deliver it to tissues elsewhere To pick up carbon dioxide from other tissues and unload it in the lungs Has glycoproteins and glycolipids that determine a person’s blood type Haemoglobin (Hb) gives red color Live for about 120 days 38  2024-02-13 Leukocytes (leukocitai) White blood cells Granulocytes Neutrophils play roles in the destruction of bacteria and the release of chemicals that kill or inhibit the growth of bacteria eosinophils destruction of allergens and inflammatory chemicals, and release enzymes that disable parasites Basophils secrete histamine and heparin Agranulocytes lymphocytes destroy cancer cells, cells infected by viruses, and foreign invading cells present antigens to activate other cells of the immune system secrete antibodies and serve in immune memory Monocytes digest pathogens, dead neutrophils, and the debris of dead cells. activate other immune cell Platelets (trombocitai) Secrete vasoconstrictors which constrict blood vessels, causing vascular spasms in broken blood vessels Form temporary platelet plugs to stop bleeding Secrete procoagulants (clotting factors) to promote blood clotting Dissolve blood clots when they are no longer needed Digest and destroy bacteria Secrete chemicals that attract neutrophils and monocytes to sites of inflammation Secrete growth factors to maintain the linings of blood vessels 39  2024-02-13 Platelets (trombocitai) During bleeding: vascular spasms, platelet plug formation blood clotting (coagulation) (krešėjimas). Hemoglobin (hemoglobinas) Hemoglobin (Hb) is a metalloprotein found in red blood cells The normal hemoglobin level a normal male adult is 13.8 – 17.2 g/dL. female (nonpregnant) should have 12.1 – 15.1 g/dL of hemoglobin 40  2024-02-13 Hemoglobin (hemoglobinas) functions Hemoglobin is an oxygen carrier. Hemoglobin is a carbon dioxide carrier. Hemoglobin gives the red color to blood. Hemoglobin maintains the shape of the red blood cells. Hemoglobin acts as a buffer. Hemoglobin interacts with other ligands. Hemoglobin degradation accumulates physiologically active catabolites. Insufficient Oxygen Carried Insufficient haemoglobin or red blood cells (anaemia) Insufficient pressure of oxygen in the air. A lack of iron. 41  2024-02-13 Anemia (mažakraujystė) Anemia is defined as a low number of red blood cells. In a routine blood test, anemia is reported as a low hemoglobin or hematocrit. Anemia (mažakraujystė) Symptoms Dizziness, lightheadness, or feeling like you are about to pass out Fast or unusual heartbeat Headache Pain, including in your bones, chest, belly, and joints Problems with growth, for children and teens Shortness of breath (dusulys) Skin that’s pale or yellow Cold hands and feet Tiredness or weakness (fatigue) 42  2024-02-13 Anemia Types and Causes There are more than 400 types of anemia, and they’re divided into three groups: Anemia caused by blood loss Anemia caused by decreased or faulty red blood cell production Anemia caused by destruction of red blood cells Hypoxia When body doesn't have enough oxygen, could get hypoxemia low oxygen in your blood Hypoxia low oxygen in your tissues The word hypoxia is sometimes used to describe both problems 43  2024-02-13 Hypoxia symptoms Changes in the color of skin, ranging from blue to cherry red Confusion Cough Fast heart rate Rapid breathing Shortness of breath Slow heart rate Sweating (prakaitavimas) Wheezing (švokštimas) Hypoxia causes Extreme anaemia, Asthma Meningitis Altitude 44  2024-02-13 Hypoxic Hypoxia Symptoms Apparent personality change. Impaired judgement Headache Tingling Increased rate of breathing - hyperventilation Muscular impairment Memory impairment Visual sensory loss Tunnel vision Impairment of consciousness Cyanosis Formication. Unconsciousness. Death. Time of Useful Consciousness (TUC) Time available for the development of hypoxia and the pilot to do something about it. Can be affected by Individual fitness Workload Smoking Overweight or obesity Decompression is progressive or explosive 45  2024-02-13 Stages/Zones of Hypoxia 1. The Indifferent Stage/Zone GL - 10 000 ft (3048 m) 2. The Compensatory Stage/Zone 10 000 ft - 15 000 ft (3048 - 4572 m) 3. The Disturbance Stage/Zone 15 000 ft - 20 000 ft (4572 - 6092 m) 4. The Critical Stage/Zone 20 000 ft - 23 000 ft (6092 - 7010 m) A healthy person is normally able to compensate for altitudes up to approximately 10 000 - 12 000 ft. 46  2024-02-13 1. The Indifferent Stage/Zone GL - 10 000 ft (3048 m) Arterial oxygen saturation of 98% to 87% Dark adaption is adversely affected (can be as low as 5000 ft). Visual sensitivity is reduced by approx. 10% Performance of new tasks may be impaired. Slight increase in heart and breathing rates occurs. 2. The Compensatory Stage/Zone 10 000 ft - 15 000 ft (3048 - 4572 m) Arterial oxygen saturation of 87% to 80% Physiological automatic responses provide some protection against hypoxia trying to maintain homeostasis. These include: An increase in the respiratory volume. An increase in cardiac output and blood pressure. However after a short time the effects of hypoxia on the CNS are perceptible causing: Drowsiness (mieguistumas). decreased judgement and memory. difficulty in performing tasks requiring mental alertness or very small movements. Short-term memory loss can be detected from about 12 000 ft. 47  2024-02-13 3. The Disturbance Stage/Zone 15 000 ft - 20 000 ft (4572 - 6092 m) Arterial oxygen saturation of 80% to 65% Physiological compensatory mechanisms are no longer capable of providing for adequate oxygenation of the tissues Symptoms: Euphoria Dizziness Sleepiness Headache Fatigue Intellectual impairment and slow thought processes Memory impairment Motor performance is severely impaired Loss of judgement ‘Grey-out’ and tunnelled vision 4. The Critical Stage/Zone 20 000 ft - 23 000 ft (6092 - 7010 m) Arterial oxygen saturation of 65% to 60% Mental performance deteriorates rapidly. Confusion and dizziness occurs within a few minutes. Total incapacitation with loss of consciousness follows with little or no warning. 48  2024-02-13 Summary of body oxygen requirement at altitude Factors Determining the Severity of and the Susceptibility to Hypoxic Hypoxia Altitude. Time Exercise (workload) Extremes of temperature Illness and fatigue Alcohol/drugs 49  2024-02-13 Prevention of Hypoxia When anticipating flying above 10 000 ft ensure that a serviceable supplementary supply of oxygen is available and that the correct method of use is known. Ensure that passengers are correctly briefed. If you smoke - stop. Fly only if you are 100% fit and you are not taking any medication or drugs. Ensure that cabin heaters are thoroughly checked and serviceable. If used, ensure that fresh air is also brought into the cabin. 50  2024-02-13 Memory and altitude Statistically significant short term memory loss was detected at both intermediate (3500m) altitudes and at high altitudes (4200m). Long term deficit in memory was detected even at intermediate altitudes after repeated exposure. Hyperventilation Overbreathing Lung ventilation in excess of the body’s needs and denotes an overriding of the normal automatic control of breathing by the brain Why it is bad? Looses too much CO2 Changes acid level in blood Haemoglobin release O2 only in acid medium 51  2024-02-13 Causes of hyperventilation Hypoxia Anxiety Motion sickness Shock Vibration Heat High g-forces Pressure breathing Symptoms of Hyperventilation Dizziness and a feeling of unreality Tingling (dilgčiojimas) Visual disturbances Hot or cold sensations Anxiety Loss of muscular coordination and impaired performance Increased heart rate Spasms Loss of consciousness 52  2024-02-13 Treatment of Hyperventilation Breathe into a paper bag Increase the Exhale CO2 into carbonic acid Brain reduces the Inhale CO2 paper bag level to its breathing rate. norm Hypoxia or Hyperventilation? If it is possibility (altitude) of hypoxia, treat as hypoxia Hyperventilation After unconsciousness Recovery Hypoxia After unconsciousness Death 53  2024-02-13 Cabin Decompression Cabin pressurisation systems regulates an internal cabin pressure Flying at 30 000 ft, feeling 6 000 – 8 000 ft Loss of cabin pressurisation Slow Rapid hypoxia cold decompression sickness the size of the cabin rupture or number of lost windows the altitude of the aircraft the amount of pressure differential between the cabin and the external environment Venturi effect of air passing over the fuselage can suck air out of the cabin up to 5000 ft difference in pressure Aircraft must rapidly descend to 10 000 ft or MSA whichever is the higher Crew protection must be the highest of priorities Decompression Sickness (DCS) Nitrogen (N2) is dissolved in the blood Body exposure to reduced pressure can lead to DCS DCS – when N2 bubbles formed. Altitude above 25 000 ft associated with DCS. Safe below 14 000 Other risk factors Hypoxia Cold Age Overweight/obesity 54  2024-02-13 Decompression Sickness (DCS) symptoms Primary Joints (sąnariai) bends Shoulder (peties), wrist (riešo), knee (kelio) and ankles (kulkšnies) most affected Skin (oda) Respiratory system (kvėpavimo sistema) Brain (smegenys) Secondary Post descent collapse Decompression Sickness in flight If the symptoms of DCS appear in any passenger or crew member, the pilot should commence an immediate descent to a level at which the symptoms are relieved Kept warm and rested Put onto a 100% oxygen supply. Urgent medical assistance on landing 55  2024-02-13 Flying and diving Do not fly within 12 hours of swimming using compressed air Avoid flying for 24 hours if a depth of 30 feet has been exceeded Acceleration A change in velocity per unit of time. Changes speed or direction Types of acceleration: Linear Angular Radial Force of gravity on earth causes a constant acceleration of 9,8 m/s2 𝐺= , where G - magnitude of an acceleration, g – gravity The actual force of 1 G for an object is equivalent to the weight of that object If 2G, person weight 90 kg, feels like 180 kg. In military fighter jets, aerobatic aircraft acceleration forces may be grater than 9G 56  2024-02-13 Acceleration The pilot's physiological response is determined by: Magnitude Duration Long (> 1 s) sensory illusions somatogravic somatogyral Short (≤ 1 s) turbulence, rough landings and heavy braking Direction G-forces Gx : acceleration acting in antero-posterior axis. + Gx = when inertial force acts from front to back Take-off – Gx = when inertial force acts from back to front landing Gy : acceleration acting in side to side axis + Gy = when inertial force acts from left to right – Gy = when inertial force acts from right to left Airelon rolls, rudder roll, vertical roll, uncontrolled aircraft Gz : acceleration acting in head to feet axis +Gz = when inertial force acts from head to feet Pull into an inside loop, pull out of a dive -Gz = when inertial force acts from feet to head Pushe over into a dive Gz - most dangerious 57  2024-02-13 Positive acceleration (+Gz) Negative acceleration (-Gz) 58  2024-02-13 Physiological effects of high G forces Circulatory system Mental function The heart and cardiovascular system unable to keep blood flowing to the brain and maintain consciousness Motion sickness Disorientation If G-forces progressively increases, might cause +Gz -Gz GREY-OUT Loss of color vision RED-OUT beyond +2Gz Blood flow from foot to the head Vision turns red BLACK-OUT Capillaries in the eyes burst under the Loss of vision (consciousness not) increased blood pressure +4 - +5Gs Could cause retinal damage G-LOC may occur within 4 to 6 sec of rapid onset of +Gz Loss of consciousness Have some tingling or numbness Have a pleasant dream Not realised that it is G-LOC Lost hearing Death 59  2024-02-13 Other effect of G-force Breathing difficulties Heartbeat abnormalities Motion sickness Fitugue Arm, leg, neck pain Maximum human tolerance to acceleration is in the horizontal plane, and is in the order of 45 Gx G-forces treatment Wearing the anti-G suites Enhance the blood flow to the brain Apply special breathing techniques Anti-G straining maneuver Hook Maneuver Well-rested, hydrated, fit Well hydrated: more circulating volume in the blood stream Easier for the heart keep the brain with the oxygen blood 60  2024-02-13 Anti-G straining maneuver Anticipate the G Tense your muscles Start the Hook Maneuver Exhale, finish the word “hook,” and inhale Breathe in and repeat Effect of G forces may increase because of Fatigue Alcohol Dehydration Illness Medication 61  2024-02-13 Carbon Monoxide (CO) Highly poisonous a colourless, odourless (bekvapis) and tasteless gas Affects: When inhaled CO is absorbed easily into the bloodstream where it attaches itself to haemoglobin with an affinity over 200 times that of Oxygen. Also reacts with other proteins and enzymes in the blood which can lead to damage to the brain, heart and nervous system Symptoms are very similar to Hypoxia 62  2024-02-13 Sources of Carbon Monoxide in Aviation Internal combustion engines piston-driven aircraft, airside vehicles and ground servicing equipment Aircraft turbine engine exhaust Auxiliary Power Unit (APU) exhaust During fire On ground can enter cabins and flight decks via open doors, hatches, unfiltered via the bleed air and air-conditioning system from other aircraft (e.g. positioned in front whilst taxiing or waiting for departure) Poorly designed and/or maintained aircraft, damaged aircraft How protect? The best protection against carbon monoxide is to avoid exposure. Ensure that aircraft heating/ventilation systems and exhaust manifolds are in good working order. Special attention should be paid to older aircrafts because of corrosion or simple or wear or tear. Turn the cabin heat fully off. Increase the rate of cabin fresh air ventilation to the maximum. Open windows if the flight profile and aircraft’s operating manual permit such an action. If available (provided it does not represent a safety or fire hazard), consider using supplemental oxygen. Land as promptly as possible. Do not hesitate to let Air Traffic Control know of your concerns, and ask for vectors to the nearest airport. Once on the ground, seek medical attention. Before continuing the flight, have the aircraft inspected by a certified mechanic. 63  2024-02-13 High-altitude environment Ozone Radiation Humidity Extreme temperature Ozone A molecule consisting of three atoms of Oxygen Concentrated in the lower part of the Stratosphere Ozone is poisonous and, in high enough concentrations, can cause headaches irritation to the respiratory system can harm lung function 64  2024-02-13 Ozone effect Make it more difficult to breathe deeply and vigorously. Cause shortness of breath, and pain when taking a deep breath. Cause coughing and sore or scratchy throat. Inflame and damage the airways. Aggravate lung diseases such as asthma, emphysema, and chronic bronchitis. Increase the frequency of asthma attacks. Make the lungs more susceptible to infection. Continue to damage the lungs even when the symptoms have disappeared. Cause chronic obstructive pulmonary disease (COPD). Radiation Two types: Galactic Solar 65  2024-02-13 Galactic radiation originates from outside the solar system and produces a steady and reasonably predicable low intensity flux of high energy particles The earth’s magnetic field deflects most of these particles Recommendation annual maximum dose 5 milisieverts (0,5 rem) Solar radiation lower energy than galactic radiation but can be intense and unpredictable an intense inflow of radiation from the sun Also called „sun storm“ has little to no effect on airplane passengers or astronauts within Earth's magnetosphere rated on a scale from S1 (minor) to S5 (extreme), determined by how many very energetic, fast solar particles move through a given space in the atmosphere. can cause complete high frequency radio blackouts, damage to electronics, memory and imaging systems on satellites, radiation poisoning to astronauts outside of Earth's magnetosphere. 66  2024-02-13 Radiation Records of cosmic radiation exposure are maintained for flights at altitudes in excess of 49,000 ft Cosmic radiation is of no significance at altitudes below about 25,000 ft because of the attenuating properties of the earth's atmosphere Effects of Radiation affect the central nervous system damage organs cause cancer - especially of the skin. 67  2024-02-13 Reducing the Effects of Radiation Little can be done by passengers to avoid the effects other than keeping high altitude travel to a minimum. Monitor crew exposure and will enforce appropriate rostering Humidity (drėgnumas) Absolute Humidity The weight of water vapour (garai) in unit volume of air which is usually expressed in g/m³. Relative Humidity (RH) The amount of water vapour present in a volume of air divided by the maximum amount of water vapour which that volume could hold at that temperature expressed as a percentage 68  2024-02-13 Humidity At an altitude of 30,000 ft, the outside air temperature is in the region of ±40◦C and is extremely dry, typically containing about 0.15 g/kg of moisture. Conditioned air entering the cabin has a relative humidity of