Physiology of FlightObjective: Know the physiology of flight.

Physiology of Flight: OverviewPrinciples and Problems of VisionSpatial Disorientation and Motion

SicknessNoise and Vibration Heat and Cold During Flight Noxious Gases and Vapors Self-Imposed Stresses

Boyle’s Law• The volume of a gas varies exactly

opposite that with the pressure of a gas.• A decrease in volume causes an

increase in pressure• An increase in volume causes a

decrease in pressure

Gas Pressu

re

14.7 psi

29.4 psi 58.8

psi

Dalton’s Law• The total pressure of a mixture of gases is equal to the sum of the partial pressure of each gas in that mixture.

Henry’s Law• The amount of a gas in a solution varies directly with the partial pressure that gas exerts on the solution.

Respiration and CirculationLess Oxygen available for the

respiratory system to capture – result? HyperventilationHypoxia

Circulatory SystemThe BendsThe Chokes

Rapid DecompressionRapid decompression at a high altitude

brings on an explosion as the pressure suddenly decreases.

Altitude TUC

45,000 feet MSL 9 to 15 seconds

40,000 feet MSL 15 to 20 seconds

35,000 feet MSL 30 to 60 seconds

30,000 feet MSL 1 to 2 minutes

28,000 feet MSL 2.5 to 3 minutes

25,000 feet MSL 3 to 5 minutes

22,000 feet MSL 5 to 10 minutes

20,000 feet MSL 30 minutes or more

Principles of Vision

Principles of Vision

Blind Spot: Where the optic nerve connects to the Retina.

Rods are responsible for vision at low light levels. They do not mediate color vision, and have a low spatial acuity. Smaller number of rods in the Fovea

Cones are active at higher light levels are capable of color vision and are responsible for high spatial acuity

We are all a little blind. That’s right, you may pass eye tests without a blink, have 20/20 vision, even see in the dark, but you could still miss seeing a jumbo jet at a mile and a half if the conditions are right. There is a blind spot in your eye about 30 degrees right of center when you are looking straight ahead. Your peripheral vision from the eye compensates for this “defect” because your brain normally combines the pictures from both eyes

Hold the picture below at arm’s length and focus both eyes on the cross that is located on the left windscreen. Now, move the picture toward your face. You should be able to see the airplane (located in the right windscreen) all the way in. Okay? Try it again with your left eye closed. The airplane will disappear and then reappear as you draw the picture closer. Ask yourself, “How much airspace will an aircraft cover during the time the other airplane disappeared?”

Principles of Vision

Blind Spot: Where the optic nerve connects to the Retina.

Rods are responsible for vision at low light levels. They do not mediate color vision, and have a low spatial acuity. Smaller number of rods in the Fovea

Cones are active at higher light levels are capable of color vision and are responsible for high spatial acuity

Principles of Night Vision

Spatial Disorientation and Motion SicknessSpatial disorientation - the

inability to accurately orient yourself with respect to the Earth’s horizon.

We use three sensory systems to maintain our orientation and equilibrium (balance).

Spatial Disorientation and Motion Sickness

The Visual System• Eyes provide the strongest

and most reliable orientation information during flight.

• When the horizon is not correct, your vestibular disorientation disappears; you may still experience visual illusions caused by false horizon.

Spatial Disorientation and Motion SicknessThe Vestibular System

Semicircular Canals

Spatial Disorientation and Motion SicknessThe Somatosensory System

• Consists of tactile pressure receptors in the skin, muscles, tendons and joints.

• Often called the “seat-of-the-pants” sense.

Noise and VibrationCause flyers more inconvenience

than any other factor in flight.Sound intensity or loudness is

measured in decibels.Vibrations are measured in

frequency.One effect of vibration is blurred

vision.

Heat and Cold During FlightThe largest amount of heat is

generated on the skin of aircraft and spacecraft as it travels at high speeds through the atmosphere.

An aircraft flying at Mach 2 has skin temperatures increased by about 400o F as a result of aerodynamic heating.

Noxious Gases and VaporsInside an enclosed cabin,

noxious gases and vapors may accumulate.

The breathing atmosphere can easily become contaminated from inside sources if care is not taken.

Carbon Monoxide.

Self-Imposed StressesAlcohol

• One drink at 10,000 feet can have the same effect as two or three drinks at sea level.

Tobacco• Smoking at 10,000 feet produces effects equivalent

to those experienced at 14,000 feet without smoking.

Drugs• Aspirin, nasal decongestants, tranquilizers or

sedatives.

Physiology of FlightObjective: Know the physiology of flight.