Saturday, July 21, 2012

Density Altitude and Winds Aloft in Flying

Density Altitude

Density altitude is pressure altitude corrected for temperature. Increasing temperature makes the air less dense. Remember how a plane flies. You create a downward force that is equal to the weight of the plane. When that downward force is greater than the  weight of the plane you are flying. Your takeoff run will increase, when the temperature is higher, later in the afternoon than a takeoff in the coolness of the morning when the air is more dense. You increase the speed of the airplane to reach a downward force of air that is equal to the weight of the plane. If everything is equal at takeoff you need more runway to achieve that downward force. 

If you think of a container at one temperature contains 20 molecules of air. If you could weigh the container it would weigh more than a container that contains just 15 molecules of air.  You weighed the first at 60 degrees and the second at 75 degrees. The density altitude is less at higher temperatures. 

High altitude has fewer molecules in the container just like the container at 75 degrees.

Flatlander pilots sometimes forget the altitude effect when taking off from mountain airports that are significantly higher than sea level flying.  Expect longer takeoff runs in the mountains.

Winds Aloft

Winds Aloft are important to fuel management on long cross country flights. Pick an altitude with the least resistance as possible that provides comfort and structure avoidance altitude. 

You can use winds aloft to pick a tail-wind for a quicker flight to a destination or return to your home base.

Winds are critical in both low and high altitude locations where turbulence could occur.

Altitude Brightness in mountains! Proper googles may be a choice. You know what you need.

At high altitudes  forecasts pay close attention to ridge and mountainous wind aloft reports. Density altitude and turbulence can affect your planes performance in critical situations. In mountains the 9,000 to 12,000 foot forecasts are important both from plane performance  and oxygen availability and use.

In eastern regions the wind velocities are lower. Turbulence can occur and thunderstorms are more frequent and just as dangerous as mountain flying.

Flight Planning is very important to a safe flight and winds aloft can make a difference.

Friday, July 20, 2012

Alkalosis and Flying Safety

Alkalosis and Flying Safety

Acute respiratory alkalosis occurs rapidly. Panic, in a crisis precipitated in flying, causes a rapid increase in your breathing rate. This is called hyperventilation.

Causes that relate to flying include:

  • Anxiety, hysteria and stress from flying or a crisis event in flying.
  • Aspirin, caffeine and coffee abuse.
  • High altitude flying where the decreased atmospheric pressure of oxygen stimulates breathing rate.
  • Lung disease where a hypoxic drive controls breathing more than carbon dioxide levels that normally control breathing.
  • Flying with a fever that stimulates the breathing center in the brain stem.
  • State of pregnancy.
  • Kidney disease that precipitates neural problems from brain swelling.
Sometimes just a "Don't Panic" cup produces "comic relief" just at the right moment!

Symptoms of Alkalosis

Decreased blood carbon dioxide causes symptoms of respiratory alkalosis. You may experience a tingling or numbness in your skin. The alkalosis may disrupt the electrolytic balance of calcium ions which may cause your skeletal muscles to remain extremely tense, for a brief time ( tetanus ) and cause fainting. If the alkalosis is caused by an underlying chronic condition pain and disorientation may occur.

The physiology of alkalosis is complex. The acute (short term) respiratory alkalosis has many causes. You must understand some habits, even enjoying several cups of coffee, may trigger alkalosis.

Distraction from your pilot in command duties is not in your best interests. Knowledge of the possible causes is safety for you and your passengers.

Thursday, July 19, 2012

Anger Control in Flying

Anger Control Tips

Is losing your "Cool" worth the consequences?

The tips below may help in controlling anger.

  • Take an Anger Management Course.
  • Know what makes you angry and recognize situations that lead you to express your anger.
  • Don't become angry when you don't receive attention you think you deserve.
  • If you feel anger arising during a conversation find a way to assert your feeling and reconcile it peacefully.
  • Anger is normal but calmly tell other people what your needs are.
  • Hey, no one wins  in a power struggle. Back off from the situation if you can.
  • Obnoxious folks are out there. Control how you act. You  control your emotions and responses.
  • Avoid things that get you mad. Think of strategies to avoid irritating people.
  • When confronted, think if getting angry is really worth all the trouble.

Wednesday, July 18, 2012

Sleep Apnea

Flying and Sleep Apnea

Memory lapses and lack of concentration while flying a plane are serious safety concerns. Sleep Apnea is a preventable factor in aviation accidents.

The United States population is changing with respect to weight. Its' putting on weight.

With weight gain you compromise an important gas exchange system. The Respiratory System can't exchange gases efficiently.

The respiratory system inhales oxygen and exhales carbon dioxide. Thats breathing and sleep apnea interferes with that function.

There are many accessories that help folks with sleep apnea. For me the CPAC was effective. I don't know the effectiveness of the devices offered.

The body and its cells restore their normal function from sleep. When physical obstructions prevent that restoration physiological changes occur. 

Sleep apnea's association with hypertension, heart attacks, stroke, obesity and diabetes are documented. These  serious conditions and flying is dangerous.

Symptoms include snoring, unusual daytime sleepiness, prolonged breathing pauses while sleeping, loss of concentration on activities and memory loss.

Weight gain, and the distribution of fat around folds surrounding the entrance to the trachea, can prevent the entrance of air entering the lungs. Structurally, the epiglottis covers the entrance to the trachea when you swallow and slides back to let air once again enter the lungs. When a person gains weight the folds increase in size which impairs the retraction of the folds. Net effect is impairment of gas exchange in the lungs.

If the lungs can't replenish oxygen to the cells during restorative sleep, a state of hypoxia begins. If carbon dioxide is retained rather than blown off, a state of acidosis begins.

If the physiological replenishing doesn't occur when you sleep,  the net effects mentioned above happen.

If you suspect you may suffer from sleep apnea because of the symptoms above and, if you're a man, have a shirt size of 17 inches or better or a body mass index greater than 30 you need evaluation.

There are treatments available for sleep apnea. It begins with an evaluation for sleep apnea by a sleep apnea specialist. It includes a detailed history and a stay overnight to evaluate.

With treatment you can avoid or delay the onset of these chronic illnesses and prolong a quality life.

Tuesday, July 17, 2012

Hypertension and Medical Certification


Elevated blood pressure. Unrecognized it is strongly associated with strokes, heart attacks, kidney failure and damage to your heart and blood vessels.

It  is called "The Silent Killer" because symptoms are not visible to you. A good physical shows whether you have high blood pressure. It is important for you to establish a "baseline" for the physician to make a decision. Why?

Blood pressure is affected by things like fear, anger, anxiety, and what you eat or drink. This is a short list. You need to establish an "average" value for your blood pressure to show your physician. One way I did this was visit my local fire department. I told the personnel attending what I wanted to do. They welcome the additional training and will suggest times to come by for testing. Keep a record and take this in for a second visit or on the first visit to your physician. It works. Remember one other factor that may give you high readings - the "white coat syndrome" and just visiting the physician can spike a reading or two.

The FAA acceptable blood pressure reading of  155 mm Hg (systolic) / 95mm Hg (diastolic) works only if it is controllable to levels much lower. Today Cardiologists would like folks to consistently be in the 115 mm Hg (systolic) / 70 mm Hg (diastolic) range.

Blood pressure medications are fine for control but there are other things you can do to help out.

  • Weight loss
  • Exercise
  • Low Salt Diets
  • A diet low in fats and rich in fruits and veggies
  • No smoking

A rule of thumb is a loss of ten percent of body weight will decrease your blood pressure by ten percent. If your blood pressure before weight loss is 160/95 a ten percent body weight loss would lower your blood pressure to 144/85.5.

Keep losing and you could reach cardiologist correct levels.

I swim everyday. South Carolina has mild winters and a wet suit will allow you to swim year round. Hey, I am 75. You can do it! I don't like pools but a lake or river (slow moving) is fine. Physical exercise lowers blood pressure. ( Get a check up before selecting a routine of physical exercise. Dying is not an acceptable method of lowering your blood pressure.

Natural foods (no unnatural foods allowed) contain only small amounts of sodium chloride (salt). Salt makes food taste better just like fat does. Processed food "soups up" their products to make them taste better. 

This is a model very similar to a wrist model I use. Be sure to check your readings with the physicians or fire department readings.

You only need 200 mg (milligrams) of salt per day. We consume large amounts above that value on the average.

Depending on the severity of your hypertension, if you follow the above changes in lifestyle you may not need medication.

The FAA has found most medications for hypertension safe and acceptable. Please, if on medications, consult your aviation medical examiner for the correct procedure for continued medical certification.

Pulse. 70 beats/minute for men; 75 for women. Keep in mind the pulse will lower with physical activity. Medication, stress, coffee, smoking and obesity will affect pulse rate the other way.

Here are ranges for Hypertension Categories:

Systolic / Diastolic Levels

Mild Stage I                  140-159 / 90-99
Moderate Stage II         160-179 / 100-109
Severe Stage III            180-209 / 110-119
Very Severe Stage IV    210+     / 120+

Monday, July 16, 2012

Metal Fatigue

Metal Fatigue

Take a small piece of wire. If you don't have wire clippers to break it, you hold it between your fingers and bend it back and forth. It heats up and eventually breaks. Thats metal fatigue in its simplest form.

Its the hidden danger you check for when you do your preflight. You look carefully at all the hinge joints. See if all the cotter keys are in place and properly fitted. If you see the beginning of a crack that is a serious sign. Know you A&E person. Listen carefully to what he or she is telling you about fatigue.

In a major air disaster an airliner lost its engine just after takeoff from a busy midwestern airport. After a very careful examination of the crash it boiled down to two things. A large hinge bolt that was the main attachment point for the engine and a powerful surge of thrust at takeoff.

This is like the example above. When too much power was applied too soon the large, heavy gross weight of the plane hesitates before it begins to move ever so slightly forward from the engine thrust. The engine moves forward slightly from the full power applied too soon. The bolt attaching the engine to the main structure of the plane begins to bend, back and forth a little, each time the plane was powered up at takeoff.

How many times has this sequence happened before the bolt broke from metal fatigue. Nobody really knows. It was a case of inertia, application of power too soon and slight movements back and forth like the wire you broke above. An inspection wouldn't show anything out of the ordinary. When it was time, it broke at a very inopportune time for all involved.

Vibrations can result in metal fatigue. Temperature changes can result in metal fatigue. The best engineering in the world can't predict metal fatigue accurately.

I was flying in the Bahamas in a 1964 S - Model Bonanza, from an earlier post on Instrument Scan, when just what we are talking about today happened. I noticed a slight position change in the needle of the ammeter gauge in the plane.

I did all the right things and landed safely at Red Aircraft Repair Facility in Ft. Lauderdale. An inspection showed all three welds that attached the rotor to the shaft of the alternator were broken. The belts that spun the rotor were all right but the shaft was not generating electricity. Metal fatigue? Bonanza Corporation was very interested in the alternator and, as a gift for letting them keep it for research purposes, outfitted the plane with a new alternator and a variety of other electrical things that virtually replaced much of everything except the engine block. I thought it was a good trade.

Try to sense what you plane is telling you. It may save your life sometime.

Sunday, July 15, 2012

Epilepsy and Aircraft Position Strobes

Epilepsy and Strobe Flashes

300,000 people in the United States that suffer Epilepsy when exposed to flashing lights or to certain visual patterns that can trigger seizures. This condition is known as photosensitive epilepsy.

The photosensitive epilepsy becomes less frequent with age and usually disappears in the twenties. People without epilepsy are disturbed by light exposure do not develop seizures but experience other symptoms like headaches,nausea, dizziness and other debilitating effects.

People who experience seizures are unaware they are sensitive to flickering lights or to certain kinds of patterns. These people may never go on to develop epilepsy, which is characterized by recurrent spontaneous seizures, though a seizure may be triggered by certain photo-light conditions.

Television screen flickering, computer monitors that flicker, certain video games and TV broadcasts that contain rapid flashes or alternating patterns of different colors and intense strobe lights that may cause seizures in photosensitive people.

It is the latter cause, strobe lights, that concerns pilots and their passengers in private planes. Frequency of the flashing strobe, its brightness, wavelength and visibility surrounding the plane at the time of the strobe operation are important possible triggers. If you are concerned about photosensitivity and are not epileptic ask your doctor about ordering an electroencephalogram (EEG) to test your brains electrical activity under various conditions including light stimulation produced by strobes positioned in front of your eyes. An abnormal response may indicate the presence of photosensitivity. 

If you are photosensitive and you want to avoid the effects brought on by strobe light exposure you can cover one eye and turn away from the light source. This is difficult in a plane. A much easier solution is turning off the strobe light system for the plane. When you are in instrument conditions and under ATC you can inform them of your possible sensitivity to the strobes.

This is a safety item I use when fishing in isolated places. It is used to signal search and rescue folks.

If a passenger informs you of prior problems with flashing lights it is your responsibility to inform them of the dangers and decide how you intend to fly safely.

You can check with the Epilepsy Foundation Board for their strobe light recommendations. Two important things you can investigate are:

  • Keep the flash under 2 Hertz with breaks every so often between flashes.
  • Place flashing strobes at a distance from each other and set them to flash together to avoid an increase in the number of individual flashes. 
I experienced one episode, with a passenger in the seat behind me, in a private plane on an instrument flight in a Beech-craft Bonanza. The plane was equipped with simultaneously firing wing-tip strobes and a fuselage strobe on the top of the aircraft that fired, by itself, after the wing-tip strobes. The plane was in heavy clouds with no turbulence and night was rapidly approaching.

The passenger became very agitated and began hitting me, from behind, with her purse. Luckily, her husband, sitting next to me, corrected her behavior and let me turn off the strobes. Things returned to normal and she apologized. 

Another factor was claustrophobia. This was her first instrument flight in a small plane and the exposure to all the elements was overwhelming to her.

Airline Flight and Claustrophobia

Airline Flight and Fear of Cramped Quarters

Claustrophobia. Are you fearful of the cramped, tiny seats that restrict your every movement you try and make? Anything different a plane, large or small, that didn't occur before contributes to anxiety. Anxiety, if not dealt with turns to fear.

A psychiatrist is a physician trained to treat psychological swings in behavior that blossom into fear. Try a psychiatrist to help you deal with your fear of physically "closed in" situations. The technical word to describe these feelings is claustrophobia.

In addition to helping you recognize why you feel the way you do the psychiatrist can immediately give you a prescription for drugs to combat your anxiety. Do not follow this advice if you are the pilot of the plane.

Drugs that quell anxiety belong to a Group called Benzodiazepines. Generic names like xanax, valiun and klonopin have sedating effects for several hours that enable some folks to fend off anxiety until airborne.

What kind of steps can you take to alleviate anxiety factors before and during a flight? Noise-canceling head phones and an iPod  can prevent airplane noise substantially. They psychologically make you forget your on an airplane.

Seat types and choices make the space you occupy bigger and less confining. Aisle seats, extra legroom seats and seats at the front of the plane help minimize claustrophobia. In some cases the position of the seat that makes it easier to find combats anxiety. 

when I was more active in flying in small planes the closing of the one and only door created immediate discomfort with some passengers. Claustrophobia hits when you least expect it to affect you.

Practice breathing. Watch your breathing rate. Breathe slowly. This is like the "Fright, Fight and Frolic" response of the Sympathetic Branch of the Autonomic Nervous System.  Triggered by an increase in breathing rate prepares you for a session with anxiety.

Before actually flying, pick out the aircraft you want to fly on for your trip. Big is better for people with known claustrophobia. Leave plenty of  time for ticketing, security check, boarding and possibly time for a snack, if that calms you down.  If you have drugs to calm you down take them an hour before your boarding time. This gives them time to start working. A bottle of water is good to buy and bring on board. Thirst (dry mouth) can trigger a panic attack. Boarding a plane later has the effect of  not being in a plane a long time before actual takeoff. Long time equates with anxiety.

These "Tips" pertain more to Commercial planes than private planes. Some apply to both type of planes.