Category Flying and Gliding

Clouds are classified according to two criteria—the amount of air movement in them and the altitude at which they typically form. Although one of the two criteria is often enough to designate a cloud type, a combination of the two is also sometimes used.

What’* it like inside a cloud? You’ve already seen it a hundred time*—in the form of fog.

Though we give fog its own name and pay a good deal of attention to it in local weather broadcasts, the insides of a cloud are identical to being in the middle of a fog bank. When fly­ing in a cloud, the sensation ranges from featureless gray to bright white to intermittent flashes of blue sky alternated with white tendrils of cloud. It all depends on the type of cloud you’re in and how close you fly to its upper boundary.

Clouds that feature air movement in the form of updrafts and downdrafts—vertical movement called convection—develop tall, billowy tops. They are called cumulus clouds, and can lend a bright, textured feeling to the sky. Convection is caused by the sun heating the earth’s surface, or by cold air moving over a warm surface.

Clouds that form in relatively still air—air that has very little convection—are called stratus clouds, and are usually flat and slate-gray in appearance. As you might guess, cumulus clouds, to a pilot, signal the presence of unstable air, while stratus clouds signal the presence of stable air.

Clouds that possess little air movement but that form in high, cold altitudes are called cirrus clouds. Cirrus clouds are thin and wispy and are made entirely of tiny ice crystals.

Below the cirrus clouds are the middle-altitude clouds designated by the prefix “alto.” If the midlevel cloud is unstable—that is, filled with convection currents—it is called altocumulus. If it is stable and is more horizontal than vertical, it is called altostratus.

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High-altitude aircraft somebmes create their own clouds. Vapor trails, or condensation trails, form in the exhaust plumes of jet engines when the water vapor contained in the exhaust condenses in the cold air. The vapor condenses into icc crystals, which can last for hours

Low clouds are simply called stratus, cumulus, or stratocumulus, meaning a scattering of lumpy, cotton-ball clouds across a wide expanse of sky, all at the same altitude, or stratum.

Turbulence

Think the study of weather is all about fluffy clouds and snow showers? Think again. Meteo­rology is among the most com­plex of all sciences, defying even the most powerful computers, which can’t precisely predict weather beyond a couple of days into the future. As technology improves, forecasting gets a little better, but weather forecasting will always be a mixture of sci­ence and bettrng the odds.

Rain clouds get their own prefix—“nimbus.” Any cloud that rains is designated with “nimbus,” for example, nimbostratus and cumulonimbus. As you might guess based on the names, nimbostratus rain clouds are mostly flat and stable. Rain from these clouds can continue for hours or days at a time. Cumulonimbus rain clouds tend to have massive, dark-gray bodies, and can tower to heights of 50,000 feet or more. They rain in sporadic showers, and have powerful up – and downdrafts that can tear the strongest airplanes to pieces.

To the seasoned cloud-watcher, every cloud carries important information. I once ignored a telltale tendril of vapor, or virga, drifting downward from the base of a cumulus cloud, and it almost cost me my life. That seemingly innocent wisp of moisture, which signifies a rain shaft that evaporates before hitting the ground, should have told me of a potentially strong downdraft that almost always accompanies virga.

Because I didn’t read the cloud accurately, I flew into a strong downdraft when I was just a couple hundred feet above the ground on approach to land. The powerful burst of air threw my plane almost into the ground, and if I were any lower, I would have crashed.

I was lucky that time and came away badly shaken but unhurt. Since then, I’ve become a much closer reader of the lessons the clouds can teach if we watch them closely.

To a pilot, clouds provide valuable clues to activity in the atmosphere. Although ideally a pilot should be armed with the latest weather reports, by scanning the clouds he can tell what sort of localized air movements may be transpiring that the most upto-date forecast may not yet contain. Before we consider the different types of clouds and what a pilot can infer from them, let’s take a look at how clouds are formed.

A Cloud is Born

Water takes one of three forms: ice, liquid, or vapor. Another name for vapor is humidity. There’s a limit to how much water vapor the air can hold, or how humid it can be. The warmer the air, the more water vapor the air can hold. The cooler the air, the less water vapor it can hold.

All air, warm or cold, has a point at which it becomes saturated and can’t hold any more water. When air reaches its saturation limit, any additional water vapor condenses, changing from invisible vapor to visible water droplets. We recognize these visible water droplets, in great masses, as clouds.

Because cold air is not able to hold as much water vapor as warm air, a moist parcel of air that cools below the dew point will also condense to form clouds.

Though its name might have a foreign sound, the Coriolis effect is familiar to anyone who has watched a spinning ice skater pull his arms inward. In the case of the earth’s rotation, a parcel of air at the equator is farthest from the earth’s pole-to-pole axis, and that means it’s moving the fastest as the planet rotates.

Turbulence

When a parcel of air at the equator is nudged northward, it moves over terrain that is closer to the axis. Like the skater pulling his arms closer to his own rotational axis, the air parcel accelerates, pushing its rotational axis toward the right, or eastward. (The same rule holds true for a parcel of air moving southward toward the equator, except that the south-moving air is slowed like a skater extending his arms. That causes the air to slow, turning it westward to the right.)

The Coriolis effect turns everything to the right, and is partly responsible for causing wind to blow clockwise around a high-pressure area and counterclockwise around a low-pressure area. The rest of the explanation comes from the “pressure gradient force” that causes air to always flow from an area of high pressure toward an area of low pressure.

To start with, air in a high-pressure area begins to move toward a low-pressure area nearby. As soon as it begins moving, the Coriolis effect turns it toward the right, causing the clockwise flow around the high-pressure region.

As the clockwise-moving high-pressure air approaches the low-pressure region, the pressure gradient force begins to balance the Coriolis effect caused by the high – pressure area. Air that moves any closer to the low-pressure region will swirl inward in a counterclockwise direction under the influence of the pressure gradient force, which is stronger close to the low-pressure center than the Coriolis effect.

In This Chapter

>■ The simple causes behind the weather”s complex behavior

V Labeling and categorizing clouds

V Understanding and avoiding turbulence

V Severe storms and you

>■ The pilot as amateur weather forecaster

All pilots are students of the weather. From their very first flight, pilots begin to develop an instinct for weather. Weather affects all aspects of a flight, from the wind whose direction determines which runway you’ll take off from to the make-up of clouds that signal the onset of stomach-turning turbulence.

Even pilots with a private pilot certificate in their pocket and hundreds of hours scribbled into their logbook keep a close watch on the weather. Without an instrument rating and special training in weather flying, private pilots are grounded by bad weather.

Weather is one of the most common factors cited as contributing to accidents, including the one in 1999 that killed John F. Kennedy Jr., his wife, and her sister. (We’ve dedicated Chapter 20, “John F. Kennedy Jr.’s Final Flight,” to examining all aspects of Kennedy’s accident, including tips on flying in clouds and in bad weather.) Even a rudimentary understanding of how the weather works can be a valuable tool for the pilot.

What Makes the Weather?

Weather on earth is created by two fundamentals of astronomy: The sun generates enormous heat, and the earth spins on its axis. All weather begins from those two simple conditions. Of course, from that simple starting point, weather can take many forms, depending on many variables, and become a quite complex science—a science called meteorology.

Weather is generated when the sun heats different parts of the earth unevenly. The rotation of the earth complicates matters by adding a circular element to the movement of huge air masses that flow like liquid over the earth’s surface.

But there’s more—the interaction between water and air. Some of the ocean’s currents transport cold water into the warm tropics and others move warm water into the chilly polar regions. The colliding boundaries between warm air, which holds large amounts of water vapor that evaporated from the warm ocean water, and cold air, which is comparatively dry, results in precipitation in the form of rain, snow, and ice.

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Water is another major player in weather. In meteorological terms, the power of water lies in its ability to absorb and radiate heat when it changes state, going from liquid to vapor and back to liquid again. Water is a primary factor in the development of severe weather, such as thunderstorms, tornadoes, and hurricanes, which we’ll discuss shortly.

The rotation of the earth is responsible for the circulation patterns of the atmosphere and for the spinning of air around high – and low-pressure areas.

Because of a phenomenon called the “Coriolis effect,” high-pressure areas rotate in a clockwise direction in the Northern Hemisphere, while low-pressure areas rotate counterclockwise. In the Southern Hemisphere, high-pressure areas rotate counterclockwise, while low-pressure areas rotate clockwise. The direction of rotation around high-and low-pressure areas dictates the direction of wind flow.

We’ve all heard that flying is statistically safer than driving a car. Yet there’s no denying that aviation can be hazardous. Tragedies like the 1999 deaths of popular golfer Payne Stewart in a gruesome jet mishap and of John F. Kennedy Jr. during a routine flight require careful examination if we are to understand the causes behind them and learn from them.

In this part, you’ll learn about the possible barriers to flying the perfect flight—from the effects of bad weather to the limitations of the human body. You’ll learn how pilots respond to flight emergencies. You’ll also read a detailed analysis of Kennedy’s final flight, as well as an examination of the decision-making factors that every pilot should understand.

Aerobatic airplanes are among the most expensive small planes to rent, not only because they are meticulously crafted but because insurance companies think aerobatic flying is more dangerous than other types of flying, and thus charge higher premiums. Aerobatics may be slightly more risky than flying straight and level, but with proper training, a well-maintained airplane, and sound judgment, aerobatics can be very safe.

Renting an aerobatic training plane is far more costly than renting most of the small trainers you might fly to earn your private pilot certificate. For example, the popular Great Lakes aerobatic trainer usually starts at $140 per hour, including fuel costs and instructor fees. Typical aerobatics courses might require 10 hours or more of flying experience.

Another popular aerobatics plane, and one that is agile enough and powerful enough to fly in competition, is the Pitts Special. Pitts are eye-catchers because of their flashy starburst paint scheme and their striking biplane design. But they can carry a hefty per-hour charge of $230 or more.

You can even find schools that will train you in the ultra-high performance Extra 300, a German-made plane that has become famous for carrying American pilots to international competitions. But the extra performance brings extra cost—$270 per hour or more, including instructor.

But there’s hope for would-be aerobatic pilots on a budget. Flying lower-performance planes such as the Standard Decathlon, a high-wing workhorse that is forgiving and docile enough for the beginner aerobatic pilot but capable of performing almost any maneuver you can imagine. The Standard Decathlon has another advantage: It’s inexpensive to fly, at least compared to the Pitts. You can rent a Decathlon, and an instructor to tell you how to fly it, for $120 per hour.

Ask pilots what the hardest part of learning aerobatic flying is, and most of them will tell you that it’s overcoming airsickness.

Though it feels like it’s in your stomach, airsickness is mostly in your head. Most flight physiologists agree that airsickness results from a psychological conflict between the extreme maneuvers of the airplane and the instinctive desire to be right side up. It comes down to a disagreement between the information the brain receives from two powerful physical sense organs—the eyes and the tiny balance organs in the inner ear. Basically, the eyes report one thing to the brain, and the inner ear reports another.

Ginger might be an effective remedy for the student pilot who suffers from airsickness early in his flight training. Available in the form of a pill from health food stores or in the form of ginger ale, ginger is nature’s airsickness tonic. Although drug stores sell over-the-counter Dramamine for airsickness, and physicians can prescribe drugs to calm the stomach flops, these should be left to the occasional traveler, not pilots. Dramamine can make you very drowsy and should never be taken before or during a flight

For example, in an aerobatic maneuver such as a loop, you are momentarily upside down, a radical change from the normal state of things for most of us and an unusual position for the brain to interpret. Yet the balance organs of the inner ear (which we will learn more about in Chapter 18, “Overcoming the Body’s Limitations”) sense g-forces that are similar to the normal pull of gravity. So the eyes say you’re upside down while your inner ear says you’re right side up (since g – forces are still pulling you into your seat). To further complicate things, a loop can put the body through a range of g-forces that might reach as high as 6 g’s during entry and recovery and could approach zero near the top. The brain is forced to sort out and interpret some unusual and, frankly, potentially frightening signals.

But the fact that airsickness has its roots in the brain doesn’t mean the physical symptoms aren’t real. Even though the feelings are largely rooted in psychological reactions, the brain creates powerful bodily responses, including sweating, over-salivating, headache, nausea, and fatigue. The result is often airsickness.

Airsickness can be a formidable enemy. I once saw a young student climb out of an airplane after a simple training flight with a face that wasn’t just pale, it was literally green—a waxy, translucent green. Unfortunately, that student and a few others I have known couldn’t conquer airsickness and had to abandon flying. But a sensitive flight instructor using modern training techniques can almost always help pilots conquer airsickness.

Like artists in any medium, aerobatic pilots often go beyond the traditional boundaries—even beyond the maneuvers that can be created by combining the four fundamental aerobatic maneuvers above.

One of the most outrageous maneuvers doesn’t just break the basic aerobatic rules—it shatters them. It’s a wild, tumbling, cart-wheeling, out-of-control hodge-podge of a stunt called a “lomcevak” (pronounced LOM-shi-vahk), which is a Czech word meaning “headache.” A lomcevak is one of the most violent things you can do in an airplane besides crash. From the ground, it looks as though the airplane is having a fit. One second, the airplane’s flying along and everything seems fine. The next, it is tumbling chaotically, sometimes tail-first, sometimes wingtip first.

If it looks crazy from the ground, it’s even worse from the cockpit. Some aerobatic pilots like to say that once they start the lomcevak (usually with lots of engine power, forward elevator, and opposite rudder and aileron controls), they don’t have any better idea of how it will end than a spectator does. The question is whether the airplane will shake off its temporary madness with its nose pointed up, down, frontward, or backward. Once the in-flight flailing stops, the pilot has to gather his wits and decide how to keep the plane flying.

In actuality, there is a method behind the fayade of chaos. There is also plenty of concern for safety. For a trained pilot and a strong airplane, the maneuver is a safe one.

The roll, combined with the spin, the loop, the hammerhead turn, and inverted flight, make up the basic elements of aerobatics. Add variations like the snap roll and the lomcevak, put these tools into the hands of a great pilot, and you have aerobatic maneuvers that make for dramatic and inspiring entertainment.

Of Aerobatics and “Comfort Bags”

Aerobatic flying is one of the few forms of flying that requires the pilot to be as fit as an athlete. For the most part, nonmilitary flying is a

relatively sedentary pursuit. But aerobatics are a big exception. Aerobatic Hying puts enormous physical stress on pilots and takes a toll on the body during even a single flight.

“G" Whiz!

To understand the demands on the body during aerobatics, you have to understand gravitational forces, or “g-forces,” which is the nickname we give to the sensation of added gravity caused by centrifugal force. For example, if a pilot executes a loop that exerts 6 g’s during a portion of a loop, he feels as though he weighs 1,200 pounds, or six times the normal force of gravity.

Acceleration comes in two flavors, at least for our discussion—linear acceleration and angular acceleration. Liner acceleration is the force that pushes you back into your car seat or that makes you feel heavier on an elevator going up. Angular acceleration, also called “centrifugal force,” is what pushes you against the wall of the rotating carnival “tilt-a-whirl” ride or tends to fling you off a fast-turning merry-go-round.

Linear, or straight-ahead, acceleration is relatively easy to visualize, and is of concern to the aerobatics pilot—except when being launched from an aircraft carrier where a pilot is jolted with several g’s when accelerating from a stop to almost 200 m. p.h. in a couple of seconds.

Centrifugal force is a bigger concern for the aerobatics pilot. Centrifugal force is what causes the g-forces that can feel as though the pull of gravity was magnified beyond

the earth’s 1 g force we live with every day. Centrifugal force during flight can turn up the g-meter inside an aerobatic plane to 10 g’s or more.

Imagine holding a toy airplane on a string and spinning it around in a small circle. If you twirl it slowly, the plane goes round and round at pretty much the same distance from the ground that it was at rest. But if you really start spinning it quickly, the plane will move higher toward your hand and bring the string itself almost parallel to the ground.

Now imagine a miniature pilot inside your model plane. When you were spinning it slowly, if that miniature pilot dropped a pencil, it would not have dropped toward the floor you were standing on but toward the bottom of the airplane, which was slightly tilted because you were spinning it.

As you spun the airplane faster, a dropped pencil would still fall toward the bottom of the plane, even though to you the plane is flying sideways. And the pencil would drop much faster because of the increased centrifugal force caused by the faster spinning.

Blackouts are what happen* when the brain is starved of оку – gen, and they usually last only a few seconds. As soon as the heavy g-forces subside, the oxy­gen is able to return to the brain. Aerobatic pilots sometimes experience the less severe "gray – oub" that can cause tunnel vision. Finally, even if a pilot doesn’t black out during heavy g-forces, the gravity can pull the eyelids down over the eye, caus­ing a "redout" (the blood vessels in the eyelid give the sunlight a reddish hue).

Now think of the pilot himself. The force that pulled the pencil to the floor more quickly is also pulling the pilot. The pilot can’t fall like the pencil because he’s restrained in his seat, so he begins to feel heavier and heavier. In other words, the pilot is experiencing more g’s.

G-forces complicate an aerobatic pilot’s life because the body is designed to function in the presence of about 1 g, the gravitational force the earth exerts on us. When a pilot makes a sharp pull-up, as entering into a loop, for example, the g-forces can spike up to several g’s. Limbs feel heavy, skin sags, eyeballs flatten out somewhat in their sockets. Worst of all, the blood supply flows toward the pilot’s feet and rear end, and can cause a blackout.

To prevent blackouts and grayouts, pilots use their chest and neck muscles to prevent the blood from leaving their heads. The concentration necessary for flying perfect aerobatic maneuvers, plus the muscle strength needed to keep the blood in the brain, where it belongs, make an aerobatic performance as strenuous as playing a set of tennis or running a 5K race.

The last of the fundamental aerobatic maneuvers is a funny little maneuver with a lot of names. Some pilots call it a hammerhead turn, others call it a hammer-head stall, still others a stalled turn. But it is commonly known as the hammerhead. For an aerobatic maneuver, it is unusual because of how slow the plane is flying when the hammerhead is performed. Here’s how it’s done.

At a relatively fast speed, the pilot pulls the nose up until it is pointed vertically to the sky. Keeping the engine at full throttle, the pilot holds the vertical flight path until the airspeed slows, then applies full rudder in one direction, let’s say toward the left.

The left rudder will cause the nose to swing left toward the left wing, and will cause the left wing to slice downward toward the ground. The pilot holds the controls this way until the airplane’s nose is pointed straight at the ground. As he descends and regains airspeed during a few seconds of being pointed straight at the ground, the pilot can gain enough speed from the combination of gravity and engine power to launch into other aerobatic maneuvers.

The hammerhead is a critical maneuver in competition aerobatics. Why? You can see that the pivot at the peak of the hammerhead has enabled the pilot to reverse his direction of flight. Part of the rules of international aerobatics contests is that pilots must perform their entire routine in an imaginary cube of only

1,000 meters (that’s about 3,300 feet). From the ground, that appears to be plenty of space, but from the air, the aerobatic box can seem as small as a postage stamp. The hammerhead enables pilots to make full use of that tiny space.

The loop is one of the simplest aerobatic maneuvers to perform and one of the easiest for spectators to recognize. It was also one of the first aerobatic maneuvers to be mastered by early aviators.

A pilot begins a loop by accelerating to a fast enough speed to carry the plane over the top of the maneuver, much as a roller coaster car must accelerate before speeding through the looping part of a ride. Then using mostly the elevator control, the pilot pulls the nose higher and higher until the plane is flying on its back. The pilot completes the loop by simply using the elevator to bring the nose “up”—up as seen from the cockpit, which is now upside down—until he recovers from the loop at the same altitude and speed he began at.

A pilot can use the loop maneuver as the basis for doing a number of other stunts. For example, at the top of the loop he can add a snap roll before continuing, a maneuver that pilots call an “avalanche.” (See, we’re already combining the basic aerobatic maneuvers to create complex ones!)

On a Roll

The ailerons, the controls on the wings that help the pilot bank the airplane right and left, can be used at the top of the loop to initiate the aileron roll. If the pilot

moves the aileron control, or stick, quickly to the left, for example, and leaves it there long enough, the plane will rotate toward the left so the left wing is pointed straight at the ground while the right wing is pointed to the sky. That “edgewise” position is sometimes called the knife-edge position, and if the pilot keeps the stick on the left, the plane will actually keep turning until it’s upside down. The aileron roll can be stopped when the wings are level in inverted flight or it can be continued until the plane has rolled 360 degrees and is once again right side up.