Tuesday, June 9, 2009

Aero Medical Facts (part 3of 3)

Spatial Disorientation:
Various complex motions and forces and certain visual scenes encountered in flight can create illusions of motion and position. Spatial disorientation from these illusions can be prevented only by visual reference to reliable, fixed points on the ground or to flight instruments. Spatial disorientation is mainly associated with flight in instrument conditions, but they can happen in visual flying
Runway Width Illusion:
A narrower-than-usual runway can create the illusion that the aircraft is at a higher altitude than it actually is. If you don't recognize this illusion, you may have a tendency to fly a low approach, risking a short landing. A wider-than-usual runway can have the opposite effect, with the risk of leveling out high or overshooting the runway. What is usual? Usual is what you are used to, so when you make your first landing at a new airfield, think about this illusion and deal with it.
Runway and Terrain Slopes:
IllusionAn up sloping runway, up sloping terrain, or both can create the illusion that the aircraft is at a higher altitude than it actually is. A low approach can result if the pilot allows this illusion to convince him/her that the aircraft is high. A down-sloping runway will have the opposite effect causing the pilot to flare or round out too high.
Featureless Terrain Illusion:
A pilot landing in a featureless area such as a dry lake bed or desert, will tend to fly a lower than normal approach, thinking he/she is to high.
Atmospheric Illusions:
Rain on the canopy will give the illusion of greater height. Haze will give the illusion of being a greater distance from the runway.
Excessive Illumination:
Light from the low sun levels, reflecting off the canopy or other surfaces can create a hazard when it obstructs other aircraft from you view. This is the perfect excuse to convince your significant other that a new pair of good sunglasses are needed. Sunglasses for protection from glare should absorb at least 85 percent of visible light (15 percent transmittance) and all colors equally (neutral transmittance), with negligible image distortion from refractive and prismatic errors. In other words, you need the good ones.
Scanning for Other Aircraft:
Scanning is the key factor in collision avoidance. In order to scan, your eyes have to be looking out of the cockpit. We have more and more sophisticated equipment in our aircraft and each piece of electronic wizardry demands a certain amount of attention. It doesn't make a bit of difference if you are perfectly on course when you're on a collision course with a twin engine airplane.While the eyes can observe an approximate 200 degree arc of the horizon at one glance, only a very small center area called the fovea, in the rear of the eye, has the ability to send a clear image to the brain. The rest of the area will be of less detail, in fact, an aircraft at a distance of 7 miles which appears in sharp focus within the center of vision would have to be as close as 7/10 of a mile in order to be recognized. Because of this physical limitation, one must scan a series of regularly spaced horizontal movements that bring successive areas of the sky into the central visual field. Break the scanning area up into 10-degree segments and stop and observe a few seconds at each area. When you stop to observe the area, look out and then back toward the aircraft. A successful scanning pattern is a very personal thing, and with practice, it will become a positive habit that will keep you safe as well as increase your flying enjoyment.
Empty-feild Myopia is a condition that occurs when flying on hazy days. The haze provides nothing specific to focus on and this causes the eye to focus 10 to 30 feet in front of your aircraft. So while you are looking, you are not seeing. An effective scan will help you avoid Empty-field Myopia. Look out in front of the aircraft and focus on something on the ground, then raise your eyes up to and above the horizon. This will force your eyes to focus beyond the 10-to-30 foot distance.
Determining Relative Altitude:
Use the horizon as a reference point. If an approaching aircraft is above the horizon it is probably above you, if it is below the horizon it should be below you.Taking Appropriate ActionBe familiar with the rules on right of way.
Collision Course Targets:
Any aircraft that appears to have no relative motion and stays in one scan quadrant is likely to be on a collision course. If the target shows no lateral or vertical motion, but increases in size, take immediate evasive action.
Recognize High Hazard:
AreasAirways, especially near navigation radio stations like a Very High Frequency Omnirange Station (VOR), and instrument approach courses at airports are areas to avoid. Knowing the locations of instrument approach courses at your local flying field and avoiding them is a must. Having a radio to monitor the common traffic advisory frequency (CTAF) is a must for aircraft operations and especially on an airport with different types of traffic. Take time to talk with the locals when first flying at a new field. Get the lay of the land and any particular traffic procedures for that field.
Canopy Conditions:
Keep it clean. This is often overlooked; however, a dirty canopy or wind screen can greatly reduce a pilot's ability to avoid other aircraft.
Visibility Conditions:
Be aware that smoke, haze, dust, rain and flying into the sun can greatly reduce your ability to avoid other aircraft.
Visual Obstructions in the Cockpit:
Become aware of blind spots in different aircraft. Always move your head and look around potential blind spots. You may even need to drop or raise a wing or maneuver the aircraft to clear your flight path.

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