RUNWAY EXCURSIONS - Cross Wind as a Factor in Runway Excursions - Runway excursions on takeoff, where the cross wind has been a significant factor, usually identify one or more factors: inappropriate flight crew decision to attempt a takeoff; inappropriate flight crew aircraft handling;•high rates of variation in surface and near-surface wind velocity; inadequate availability of information about the state of the runway surface; and incomplete understanding by flight crew of the aircraft performance limitations or recommendations in relation to cross wind takeoffs

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Runway Excursions

Cross Wind as a Factor in Runway Excursions

Investigation of Runway Excursions on takeoff, where the cross wind has been a significant factor, usually identify one or more of the following factors:

·       Inappropriate flight crew decision to attempt a takeoff

The origin of such a decision usually lies in poor Crew Resource Management.

Sometimes this relates to the ‘original’ decision to commence preparation for departure which later becomes clearly questionable but is not effectively reviewed.

Both Operator Culture and Authority Gradients between flight crew members can play a role in this scenario.

·       Inappropriate flight crew aircraft handling

This may arise directly from poor skills, especially where the simulator training for the aircraft type is carried out in devices which cannot realistically replicate low level wind velocity.

It may be related to insufficient understanding of the ‘basic theory’ of directional control during takeoff, or it may be related to the use of inappropriate, or possibly unapproved or non-recommended techniques for aircraft control during acceleration to takeoff speed.

·       High rates of variation in surface and near-surface wind velocity

Gusty wind, variable wind direction or wind that is intermittently blocked by airport structures or terrain features can make directional control during the takeoff run more difficult.

·       Inadequate availability of information about the state of the runway surface

When a runway is declared to be contaminated, there are clearly specified processes for measuring and communicating surface friction.

A reduction in friction index or braking action normally correlates to a reduced maximum allowable cross wind value and the reduction mat be considerable.

The modified cross wind takeoff limitations or recommendations should be published in the Aircraft Flight Manual (AFM) or the Operations Manual.

·       Incomplete understanding by flight crew of the aircraft performance limitations or recommendations in relation to cross wind takeoffs

Aircraft limitations for dry runway operations can be expected to be unequivocal in their specification and may be qualified by runway width.

By contrast, the limitations or recommendations for runways which are not dry may be difficult for flight crew to apply on the basis of the information they have on runway surface condition and cross wind component at any point in time. It is important that flight crew have clear Operations

Manual guidance on restrictions to dry runway crosswind limitations and any necessary clarification on how to interpret the guidance material for wet or contaminated surfaces.

https://www.skybrary.aero/index.php/Cross_Wind_Takeoff_Hazards_and_Techniques

 

TIPS AND TRICKS FOR MOBILE PHONE USE - Things You Never Knew Your Cell Phone Could Do - Viral message purports to clue readers in on a number of little known tips and tricks for mobile phone use, including dialing 112 to access a worldwide emergency network. Beware of forwarded emails offering esoteric tips and tricks "you never knew." Most of the claims in this message are either false or have limited applicability in the real world.

 
 bTips And Tricks For Mobile Phone Use

Things You Never Knew Your Cell Phone Could Do

by David Emery

Viral message purports to clue readers in on a number of little known tips and tricks for mobile phone use, including dialing 112 to access a worldwide emergency network.

Description

Viral text / Forwarded email

Circulating since

Sep. 2005 (multiple versions)

Status: Mostly false

(see details below)

Example

Email text contributed by Greg M., Feb. 15, 2007:

THINGS YOU NEVER KNEW YOUR CELL PHONE COULD DO.
There are a few things that can be done in times of grave emergencies. Your mobile phone can actually be a life saver or an emergency tool for survival. Check out the things that you can do with it:
FIRST
Subject: Emergency
The Emergency Number worldwide for Mobile is 112. If you find yourself out of the coverage area of your mobile; network and there is an emergency, dial 112 and the mobile will search any existing network to establish the emergency number for you, and interestingly this number 112 can be dialed even if the keypad is locked. Try it out.
SECOND
Subject: Have you locked your keys in the car?
Does your car have remote keyless entry? This may come in handy someday. Good reason to own a cell phone: If you lock your keys in the car and the spare keys are at home, call someone at home on their cell phone from your cell phone. Hold your cell phone about a foot from your car door and have the person at your home press the unlock button, holding it near the mobile phone on their end. Your car will unlock. Saves someone from having to drive your keys to you. Distance is no object. You could be hundreds of miles away, and if you can reach someone who has the other "remote" for your car, you can unlock the doors (or the trunk). Editor's Note: It works fine! We tried it out and it unlocked our car over a cell phone!"
THIRD
Subject: Hidden Battery Power
Imagine your cell battery is very low. To activate, press the keys *3370# your cell will restart with this reserve and the instrument will show a 50% increase in battery. This reserve will get charged when you charge your cell next time.
FOURTH
How to disable a STOLEN mobile phone?
To check your Mobile phone's serial number, key in the following digits on your phone: * # 0 6 # A 15 digit code will appear on the screen. This number is unique to your handset. Write it down and keep it somewhere safe. When your phone gets stolen, you can phone your service provider and give them this code. They will then be able to block your handset so even if the thief changes the SIM card, your phone will be totally useless. You probably won't get your phone back, but at least you know that whoever stole it can't use/sell it either. If everybody does this, there would be no point in people stealing mobile phones.
And Finally...
FIFTH
Cell phone companies are charging us $1.00 to $1.75 or more for 411 information calls when they don't have to. Most of us do not carry a telephone directory in our vehicle, which makes this situation even more of a problem. When you need to use the 411 information option, simply dial: (800) FREE 411, or (800) 373-3411 without incurring any charge at all. Program this into your cell phone now. This is the kind of information people don't mind receiving, so pass it on to your family and friends.

Analysis

Beware of forwarded emails offering esoteric tips and tricks "you never knew."

Most of the claims in this message are either false or have limited applicability in the real world. We'll examine them one by one.

CLAIM: The worldwide emergency number for cell phones is 112.
Not quite. 112 is the Europe-wide emergency phone number. Throughout most of the European Union and some neighboring countries, dialing 112 will connect callers to local emergency services. The system doesn't include North and South America, Asia, or Africa.

According to some sources, many, but not all, cell phone models are pre-programmed to redirect calls made to any of the most common emergency numbers (e.g., 911, 999, 000, 112) to the proper local services regardless of the caller's location.

And many, but not all, cell phone models and service providers will allow the most common emergency numbers to be dialed even if the caller is outside his or her regular service area, or the phone lacks a SIM card.

However, no mobile phones can put through calls, emergency or otherwise, from locations where no cell service exists at all.

Within the U.S., dialing 911 remains the most direct and reliable way of contacting emergency services regardless of what kind of phone you use. Don’t dial 112 unless you want to play Russian Roulette with your life.

CLAIM: Unlock a car door with your cell phone and a spare remote key.
False. As discussed previously in these pages, cell phones and remote keyless entry systems work on entirely different radio frequencies. Therefore, cell phones are incapable of re-transmitting the signal from a remote key to unlock a car door.

CLAIM: Press *3370# to access 'reserve battery power.'
False. On some Nokia phones, users can punch in special codes and toggle between speech codec modes to 1) enhance voice transmission quality at the cost of diminished battery performance, or 2) enhance battery performance by decreasing voice quality.

Apparently, some users have misconstrued the latter as "tapping into reserve battery power." On that score the email is doubly erroneous because *3370# is the code for enhancing voice quality — so using it actually decreases battery life!

CLAIM: Press *#06# to disable a stolen cell phone.
Not exactly. On some cell phone models, but not all, pressing *#06# will cause the phone's 15-digit International Mobile Equipment Identity to be displayed. Some service providers, but not all, can use that information to deactivate the handset.

In any case, it isn't necessary to supply an IMEI number to cancel your cellular account in the event of theft; simply call your provider, give them the appropriate account information, and tell them the phone was stolen.

CLAIM: Make 411 calls on your cell phone without charge by dialing (800) FREE 411.
Basically true (see previous comments on Free 411), though cell phone users may still incur a charge for minutes used, depending on the specifics of their plan.

David Emery

·   Noted chronicler of folklore and debunker of urban legends since 1997

·   Senior writer at popular online fact-checking website  Snopes.com

·   Lauded in "The Complete Idiot's Guide to Urban Legends" and "Encyclopedia of Urban Legends"

Experience

David Emery is a former writer for ThoughtCo who contributed articles on urban legends for 19 years. He has more than two decades of experience as an internet folklore expert and debunker of urban legends, hoaxes, and popular misconceptions.

David is currently a senior writer at Snopes.com, a popular online fact-checking website. He first won recognition in the online universe as a commentator on the outer limits of internet culture after creating Iron Skillet Magazine in 1997. The website, which he ran for one year, curated and annotated the "Wild Weird Web." David has also been lauded by Brandon Toropov in "The Complete Idiot's Guide to Urban Legends" and Jan Harold Brunvand in "Encyclopedia of Urban Legends."

Education

David holds a B.A. in philosophy from Portland State University.

Awards and Publications

·   Snopes.com

·   Iron Skillet Magazine

ThoughtCo and Dotdash

ThoughtCo is a premier reference site focusing on expert-created education content. We are one of the top-10 information sites in the world as rated by comScore, a leading Internet measurement company. Every month, more than 13 million readers seek answers to their questions on ThoughtCo.

For more than 20 years, Dotdash brands have been helping people find answers, solve problems, and get inspired. We are one of the top-20 largest content publishers on the Internet according to comScore, and reach more than 30% of the U.S. population monthly. Our brands collectively have won more than 20 industry awards in the last year alone, and recently Dotdash was named Publisher of the Year by Digiday, a leading industry publication.

https://www.thoughtco.com/things-you-never-knew-your-cell-phone-could-do-3299001

THE STEEL MAN - HENRY BESSEMER - Sir Henry Bessemer, an Englishman, invented the first process for mass-producing steel inexpensively in the 19th century. Bessemer was knighted in 1879 for his contributions to science. The "Bessemer Process" for mass-producing steel was named after him. Modern steel is made using technology based on Bessemer’s process. It was an essential contribution to the development of modern day skyscrapers.

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Henry Bessemer - The Steel Man

Henry Bessemer and the Production of Steel

by Mary Bellis

Sir Henry Bessemer, an Englishman, invented the first process for mass-producing steel inexpensively in the 19th century.

It was an essential contribution to the development of modern day skyscrapers.

The First System for Manufacturing Steel

An American, William Kelly, initially held a patent for "a system of air blowing the carbon out of pig iron," a method of steel production known as the pneumatic process.

Air was blown through molten pig iron to oxidize and remove unwanted impurities.

This was Bessemer’s starting point. When Kelly went bankrupt, Bessemer – who had been working on a similar process for making steel – bought his patent.

Bessemer patented "a decarbonization process utilizing a blast of air" in 1855.

Modern Steel

Modern steel is made using technology based on Bessemer’s process.

On the making of the first steel ingot, Bessemer said:

"I well remember how anxiously I awaited the blowing of the first 7-cwt. charge of pig iron. I had engaged an iron founder's furnace attendant to manage the cupola and the melting of the charge.

“When his metal was nearly all melted, he came to me and said hurriedly, 'Where be going to put the metal, maister?’

“I said, ‘I want you to run it by a gutter into that little furnace,’ pointing to the converter, ‘from which you have just raked out all the fuel, and then I shall blow cold air through it to make it hot.’

“The man looked at me in a way in which surprise and pity for my ignorance seemed curiously blended, and he said, ‘It will soon be all of a lump.’

“Notwithstanding this prediction, the metal was run in, and I awaited with much impatience the result. The first element attacked by the atmospheric oxygen is the silicon, generally present in pig iron to the extent of 1 1/2 to 2 percent; it is the white metallic substance of which flint is the acid silicate. Its combustion furnishes a great deal of heat, but it is very undemonstrative, a few sparks and hot gases only indicating the fact that something is going quietly on.

“But after an interval of 10 or 12 minutes, when the carbon contained in grey pig iron to the extent of about 3 percent is seized on by the oxygen, a voluminous white flame is produced which rushes out of the openings provided for its escape from the upper chamber, and it brilliantly illuminates the whole space around.

“This chamber proved a perfect cure for the rush of slags and metal from the upper central opening of the first converter. I watched with some anxiety for the expected cessation of the flame as the carbon gradually burnt out. It took place almost suddenly, and thus indicated the entire decarburisation of the metal.

“The furnace was then tapped, when out rushed a limpid stream of incandescent malleable iron, almost too brilliant for the eye to rest upon. It was allowed to flow vertically into the parallel undivided ingot mould.

“Then came the question, would the ingot shrink enough, and the cold iron mould expand enough, to allow the ingot to be pushed out? An interval of eight or 10 minutes was allowed, and then, on the application of hydraulic force to the ram, the ingot rose entirely out of the mould and stood there ready for removal."

Bessemer was knighted in 1879 for his contributions to science. The "Bessemer Process" for mass-producing steel was named after him.

Robert Mushet is credited with inventing tungsten steel in 1868, and Henry Brearly invented stainless steel in 1916.

Mary Bellis

·   New York-based film producer and director

·   Singled out by Forbes magazine for her writing on inventors. 

·   Known in art and independent film circles by the name CalmX

·   Creator of computer-generated art

Experience

Mary Bellis was a former writer for ThoughtCo, where she covered inventors for 18 years. She was a freelance writer, film producer, and director.  In addition, Forbes Best of the Web credited her for creating the number one online destination for information about inventors and inventions. Her writing has been reprinted and referenced in numerous educational books and articles. She was known for her short independent  films and documentaries, including one on Alexander Graham Bell. She specialized in making and exhibiting computer-generated art, while working as an animator, journalist and an independent video game developer. She died on March 28, 2015.  

Education

Mary Bellis held a Master of Fine Arts in film and animation from the San Francisco Art Institute.

ThoughtCo and Dotdash

ThoughtCo is a premier reference site focusing on expert-created education content. We are one of the top-10 information sites in the world as rated by comScore, a leading Internet measurement company. Every month, more than 13 million readers seek answers to their questions on ThoughtCo.

For more than 20 years, Dotdash brands have been helping people find answers, solve problems, and get inspired. We are one of the top-20 largest content publishers on the Internet according to comScore, and reach more than 30% of the U.S. population monthly. Our brands collectively have won more than 20 industry awards in the last year alone, and recently Dotdash was named Publisher of the Year by Digiday, a leading industry publication.

https://www.thoughtco.com/henry-bessemer-the-steel-man-4075538

VOLATILE SUBSTANCES - Volatility is a measure of how readily a substance vaporizes or transitions from a liquid phase to a gas phase. The term can also be applied to the phase change from solid state to vapor, which is called sublimation. A volatile substance has a high vapor pressure at a given temperature compared with a nonvolatile compound. The higher the vapor pressure of a compound, the more volatile it is. Higher vapor pressure and volatility translate into a lower boiling point.

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Volatile Substances

What Is a Volatile Substance in Chemistry?

Volatility refers to a substance's ability to vaporize

by Anne Marie Helmenstine, Ph.D.

In chemistry, the word "volatile" refers to a substance that vaporizes readily.

Volatility is a measure of how readily a substance vaporizes or transitions from a liquid phase to a gas phase.

The term can also be applied to the phase change from solid state to vapor, which is called sublimation.

A volatile substance has a high vapor pressure at a given temperature compared with a nonvolatile compound.

Examples of Volatile Substances

·       Mercury is a volatile element. Liquid mercury had a high vapor pressure, readily releasing particles into the air.

·       Dry ice is a volatile inorganic compound that sublimates at room temperature from the solid phase into carbon dioxide vapor.

·       Osmium tetroxide (OsO₄) is another volatile inorganic compound that, like dry ice, transitions from the solid phase to the vapor phase without becoming a liquid.

·       Many organic compounds are volatile. An example is alcohol. Because volatile substances readily vaporize, they mix with air and may be smelled (if they have an odor).

Xylene and benzene are two volatile organic compounds with distinctive scents.

Relationship Between Volatility, Temperature, and Pressure

The higher the vapor pressure of a compound, the more volatile it is. Higher vapor pressure and volatility translate into a lower boiling point.

Increasing temperature increases vapor pressure, which is the pressure at which the gas phase is in equilibrium with the liquid or solid phase. 

Anne Marie Helmenstine, Ph.D.

·   Ph.D. in biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.

·   Science educator with experience teaching chemistry, biology, astronomy, and physics at the high school, college, and graduate levels.

·   ThoughtCo and About Education chemistry expert since 2001.

·   Widely-published graphic artist, responsible for printable periodic tables and other illustrations used in science.

Experience

Anne Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education since 2001, and other sciences since 2013. She taught chemistry, biology, astronomy, and physics at the high school, college, and graduate levels. She has worked as a research scientist and also abstracting and indexing diverse scientific literature for the Department of Energy.

In addition to her work as a science writer, Dr. Helmenstine currently serves as a scientific consultant, specializing in problems requiring an interdisciplinary approach. Previously, she worked as a research scientist and college professor.

Education

Dr. Helmenstine holds a Ph.D. in biomedical sciences from the University of Tennessee at Knoxville and a B.A. in physics and mathematics with a minor in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive chemical detection and medical diagnostic tests.

Anne Marie Helmenstine, Ph.D.​

ThoughtCo and Dotdash

ThoughtCo is a premier reference site focusing on expert-created education content. We are one of the top-10 information sites in the world as rated by comScore, a leading Internet measurement company. Every month, more than 13 million readers seek answers to their questions on ThoughtCo.

For more than 20 years, Dotdash brands have been helping people find answers, solve problems, and get inspired. We are one of the top-20 largest content publishers on the Internet according to comScore, and reach more than 30% of the U.S. population monthly. Our brands collectively have won more than 20 industry awards in the last year alone, and recently Dotdash was named Publisher of the Year by Digiday, a leading industry publication.

https://www.thoughtco.com/definition-of-volatile-604685

CLIMBING GEARS - There are many different styles and variations of rock climbing. Traditional climbing don't have permanent anchors for climbers, using only your hands and feet and some protective gear. Sport climbing involves the use of protection or permanent anchors that are attached to rock walls. When bouldering, the climber is usually no more than 12 feet (3.6 meters) off the ground. Ice climbing routes add the challenge of snow and ice, while mountaineering involves hiking or trekking in higher altitudes, often over several days or more. The two most dangerous forms are solo climbing, which is climbing alone without a partner or rope and protection, and deep water solo climbing, which involves climbing a rock and falling into deep water. Indoor (or gym) climbing on specially constructed walls is a great way for beginners to learn about climbing and improve their fitness.

....................................................................

Climbing Gears

How Climbing Gear Works

BY MARIE WILLSEY

Mountain climbing: The challenge of a vertical ascent promises exhilaration, beautiful views and a rewarding sense of achievement.

Wherever there are mountains to climb, you'll find folks who are drawn to the sport and its unique challenges, welcoming the chance to test their skills, strength, endurance and teamwork.

There are many different styles and variations of rock climbing, so anyone from the weekend adventurer to the seasoned mountaineer can enjoy the sport. 

Traditional climbing involves taking rock climbs along routes that don't have permanent anchors for climbers, using only your hands and feet and some protective gear. 

Sport climbinginvolves the use of protection or permanent anchors that are attached to rock walls.

When bouldering, the climber is usually no more than 12 feet (3.6 meters) off the ground as he works his way through a boulder route called a problem. It's an extreme sport that emphasizes fitness, creativity, problem solving and teamwork. 

Ice climbing routes add the challenge of snow and ice, while mountaineering involves hiking or trekking in higher altitudes, often over several days or more.

The two most dangerous forms are solo climbing, which is climbing alone without a partner or rope and protection, and deep water solo climbing, which involves climbing a rock and falling into deep water.

Indoor (or gym) climbing on specially constructed walls is a great way for beginners to learn about climbing and improve their fitness. It's also an effective way to train year-round, improving climbing skills and having fun.

No matter what style of climbing you choose, you'll find that rock climbing is a sport with language and gear all its own. Where else will you hear enthusiasts discussing crampons, carabiners, belays and crash pads?

If you're just getting started, the right gear makes all the difference. As your skills and the difficulty of your climbs increase, you'll find that owning quality gear that will grow with you is a smart investment.

So whether you're heading for Kilimanjaro, Mount Hood, the nearest mountain range or the wall at the local gym, your equipment bag -- and your vocabulary -- should include a few basic pieces of equipment.

Learn more about climbing rope, shoes, crampons, ice axes, harnesses, crash pads, as well as belay and rappel devices and more in this article.

Climbing Ropes

What type of rope do you need? That depends on the type of climbing you plan to do, whether sport climbing, big walls, alpine or rescue.

One of the most versatile ropes is a 60-meter-long (196.8-feet) dry rope with a 9.8 millimeter to 10.2 millimeter thickness.

When shopping for a rope, it helps to know a little about rope anatomy. Most ropes have a kernmantle construction, consisting of a sheath and a core.

The sheath is the protective, braided cover of the rope that protects the core and adds strength and shock absorption.

Sheaths make up 30 to 40 percent of a rope's mass. The thicker the sheath, the more it resists cutting and abrasion.

The core refers to the inner twisted core strands of the rope. 

Filament is the thinnest thread that a rope is woven from, and twisted groups of four to six filaments make up yarns. 

Yarns are bundled together to make the core.

ng a climbing shoe, consider your climbing plans. Will you be doing most of your climbing in the gym, across boulders or on sheer mountain faces?

Here's the skinny on ropes:

·  Workhouse singles have a larger diameter and hold up to lots of use. This rope is ideal for big walls, top roping (when a rope is secured to an anchor point at the top of the route before the climb begins) and extreme use. On the downside, it can be bulky and heavy to carry.

·  All-round singles are the do-everything rope. They have average diameter, weight and fall ratings (a measurement of the stress applied to a rope if a fall occurs). They're ideal for sport, traditional and alpine climbing.

·  Skinny singles are ideal for very long or difficult climbs because they're lightweight. On long routes when you're turning over many belays, constantly pulling in slack or in an alpine situation where you're coiling rope over your shoulder and using switching techniques to move back and forth up a long climb, the lighter weight can make a big difference in the long run.

·  Half ropes, also known as a double rope, are two identical ropes used as a pair. They can run parallel through the protection using a twin rope technique, or you can alternate the "right" and "left" ropes through different protection points. They're good for long, wandering routes on rock, ice or alpine routes when you might need to rappel or retreat. (A wandering route is an indirect path to the summit, whereas a non-wandering route is more direct and vertical.)

·  Twin ropes are a good two-rope option. They're lighter and less bulky than half ropes and good for ice climbs and straight non-wandering rock climbs where repelling is necessary.

·  Static ropes are used in situations when you don't want rope to stretch, such as repelling, rescue and big-wall ascending, or anytime you're lowering, ascending or pulling a load up with the rope.

Climbing Shoes

Rock climbing shoes come in a variety of colors, designs and materials, but the most important characteristic is fit and comfort. Expect to pay between $75 and $150 for a quality pair.

When you're choosiThe first shoe most climbers choose is in the all-day comfort category. You'll want to choose one that fits like a running shoe, but the tip of your longest toe should touch the end of the shoe.

A snug fit helps make your feet more powerful when you're climbing cracks, crystals or overhanging rock.

Climbing shoe uppers, the part that surrounds your foot and sits atop the sole, are constructed of either leather or synthetic material.

Leather is easiest to care for. Unlined leather shoes can stretch, so be sure you can feel your toe knuckles pushing against the leather.

Lined leather reduces stretch. Synthetic uppers don't stretch as much. New synthetic materials breathe and whisk away sweat.

You'll also notice several different types of closure systems.

A lace up is the traditional, versatile style. Hook-and-loop closures offer easier on/off conveniences and work best for bouldering and gym climbing. 

Slippers simply slip on your feet; they have thinner soles and allow you to "feel" the rock much more than lace up shoes will.

They're the easiest to wear and pack, and slippers are often the choice of more experienced climbers. Since they usually don't have a stiff sole and midsole, wearing them for training helps your feet gain strength.

The most important factor is fit. Be sure to try on a variety of styles to find the pair that best fits your foot and your climbing style.

Climbing experts suggest trying on shoes in the afternoon since your feet swell during the day: you'll get an even better fit after an active day that includes a walk, run or climb.

Crampons

Crampons, which look like metal skeletons with sharp points, attach to your climbing shoes for extra traction when you're climbing on snow and ice.

Usually made of steel or aluminum, the frame fits beneath the soles of your shoes and is attached by adjustable straps or clamps.

Most crampons have 10 or 12 points. If they have 12 points, the two pointed straight out on the toe make frontpointing easier. The sharp points bite into the ice or whatever surface you're climbing for a more secure hold.

Crampons are specialized for various activities. For everyday winter walking over snow, super-lightweight traction devices are a good choice.

Other models are suited for snow and glaciers, technical hiking and winter or summer mountaineering.

You can even find crampons designed especially for frozen waterfalls or routes that involve both ice and rock that allow you to adjust the length and the pitch, or angle, of the points.

Most crampons feature a semi-rigid design that performs well in a variety of conditions from simply walking over winter snow to moderate ice climbing.

Some allow you to adjust the linking bar between the toe and heelpiece (which helps gives you traction and support when walking in the snow and ice) to change to a flexible mode for more comfortable hiking over forgiving terrain.

WHAT'S A BIG WALL?

Think Big Dome. Think El Capitan. These big rock faces in Yosemite National Park are iconic examples of big walls:

They're more than 1,500 feet (4,572 meters) high with few ledges and they require more than one day to scale.

Experienced, well-conditioned climbers use portaledges, or hanging tents, and hauling equipment when they set out to conquer these big walls.

Climbing Harnesses

Like climbing ropes and shoes, climbing harnesses are made for different types of climbing. Whether you enjoy sport, gym, alpine, wall, ice or general climbing, there's a harness that's right for your climb.

The harness is used to secure the climber to a rope or from an anchor point.

When choosing a harness, consider your climbing plans and the features that are important to you. Are you a beginner, planning on occasional outdoor climbs?

Do you want a lightweight harness or one that's more comfortable? Once you have your goals in mind, consider the different styles of harnesses. Prices range from $50 to $200.

·  Gym and competition harnesses feature a slim design, narrow webbing, little padding and few extras or loops for gear. Use for sport routes, gym and competition climbing.

·  All around or multi-purpose harnesses are good for all kinds of climbing and all kinds of body types and budgets. They feature padded leg loops and waist belt, detachable leg loops and gear loops for hooking your gear on the waist belt and a dedicated belay/rappel loop on the front so you can belay or rappel from it.

·  Big wall harnesses are intended for climbing on long routes that might take several days to traverse. Comfort on these long hauls is important, so they have thick waist and leg padding, as well as multiple gear loops.

·  Alpine harnesses are designed for mountaineering. They're lightweight, and they're easily adjustable to fit over many layers of clothes and made of water-repellent nylon to stand up to wet and snowy mountain conditions. Lightweight, inexpensive and adjustable to different body types, this harness makes a great extra to keep in your pack for a friend.

·  Chest harnesses are used with a seat harness, and they are good to use on routes where there's a chance of flipping upside down or falling into a crevasse on a glacier.

·  Body harnesses are made for children and adults with narrow waists and hips to prevent the climber from flipping upside down during a fall.

   Be sure to try on several harnesses to see which one fits best. And if possible, put it to a real-life test: Hang in the harness to make sure you're comfortable with its fit and feel.

Ice Axes

Mountain climbers rely on ice axes when traveling routes that involve ice and snow. This versatile tool can be used in several ways, depending on the conditions you encounter.

An ice axe may be used as a walking stick when the climber holds the head in the center with the pick pointing backwards.

It also can be used to form a secure anchor to bring up, or belay, a second climber. An axe is also a useful tool to cut footsteps in the ice or snow or to scoop out seats or trenches.

There are two classifications of ice axes: basic and technical. Basic axes are designed for the beginner or casual climber, and they're best suited for basic support.

Technical grade axes have stronger shafts, and they can be used for vertical, technical climbing or in belaying.

There are five key components of an ice axe:

1.The head is made of steel and features a pick and adze, a tool for smoothing rough cut wood. There's a hole in the center for attaching a wrist leash or carabiner.

2.The pick is the pointed end of the head, slightly curved to help with ergonomics.

3.The adze is the flat, wide end of the head used for chopping steps in hard snow and ice.

4.The shaft is straight or slightly angled. Today, shafts are usually made of aluminum or titanium or a composite.

5.The spike, or ferrule, is a steel point at the end of the shaft used for balance when the climber is holding the axe by its handle like a walking stick.

Ice axes range in price from $75 for the most basic steel and aluminum model to more than $300 for an advanced ice tool with a carbon fiber shaft.

ICE AXE ACCESSORIES

Even your ice axe can be accessorized to improve its functionality.

Try a leash to help secure the axe to your hand, a leash stop in leather or metal to keep the leash from slipping off your hand, or a snow basket mounted close to the spike to keep the shaft from sinking into the snow.

Belay and Rappel Devices

A belay device is used in belaying, when one climber secures the rope for another climber as he ascends. It's the basis of climbing safety -- it holds the rope and the other climber in case of a fall.

The rope links the climber and the belayer in a safety partnership, allowing the climber to fall without fear of hitting the ground. It's also used in rappelling, or sliding down the rope to reach the ground.

Sometimes called a BD, a belaying device allows the belaying climber to hold the active climber's fall via the friction of the rope as it runs through the device.

The rope, anchored to safety gear at the top of the wall, is attached to the climber and the belayer. The climber is tied to the end of the rope, while the belayer is attached to the rope with a belay device, a mechanical device that makes it possible for the belayer to hold the climber's weight.

The belayer must keep the rope snug on the climber as he ascends, hold him if he falls, and lower him back to the base after reaching the top of the wall.

Belay devices are available in many different sizes, styles and shapes. Some are interlocking devices.

Made of aluminum or an alloy, BDs are an essential piece of gear for every climber to own and use.

The belay device attaches to the harness of a belayer using a carabiner, a metal loop with a spring or screwed gate.

Carabiners also come in different shapes, including the versatile oval, the D shape with a larger opening that makes clipping the rope easier, and locking versions that are ideal for belaying or setting anchor.

Good quality carabiners can help your rope to last longer.

Crash Pads

Crash pads are a beautifully simple idea: They're placed between the climber and the ground to help reduce the impact from falls.

Crash pads are made of foam, covered with a durable fabric and feature straps or handles for easier handling.

Crash pads are most often used for bouldering and sport climbing when routes are determined before the climb, and they're positioned beneath tricky locations where a climber is most likely to lose footing and fall.

While the first commercial crash pads did not appear on the market until 1993, many climbers today rely on crash pads to help protect their bones from occasional falls.

There are dozens of options on the market, ranging from $75 to more than $350, and they range in size from the popular 3 foot by 4 foot (0.9 meter by 1.2 meter) pad that fits in a gear pack to larger pads that are designed for more permanent placement.

When shopping for a crash pad, look for one with a good foam quality to cushion the force of impact and absorb the shock of the fall. You should feel like you're falling into a sand pit, not a trampoline.

MORE GEAR FOR YOUR PACK

Once you're equipped with the basics, consider adding a few well-chosen accessories. Sunglasses protect your eyes from bright light, including sun reflecting from snow.

Sunglasses designed especially for rock climbing have an outer rim to protect your eyes from small debris.

Chalk will help keep your hands dry, which will help you maintain a secure grip.

A compass is a traditional tool, but today's climbers often carry a portable Global Positioning System (GPS) device to help them stay on track.

Hydration packs provide thirst-quenching convenience and help prevent dehydration. Knives and multi-purpose tools always come in handy.

And finally, you'll need a backpack that's lightweight and comfortable, yet large enough to hold your essentials.

Testing Climbing Gear

Climbing equipment is tested and certified by the International Federation of Mountaineering Associations, or UIAA. The UIAA works closely with the industry to develop standards to minimize accidents caused by equipment failure.

Most manufacturers follow the standards determined by this organization, although laws requiring certification vary from country to country.

The UIAA first started to test ropes in 1960. Its main testing criteria includes the number of falls a rope can hold before breaking, how much impact it can withstand, the static elongation, or how much stretch results when a 176-pound (80.2-kilogram) weight hangs from it, and the dynamic elongation that results in the length of a rope after a fall.

Today, the UIAA has standards for 20 different categories of equipment, including helmets, harnesses and crampons. Climbing gear such as slings and carabiners are strength tested by UIAA, the manufacturer or an independent testing agency.

Strength tests evaluate the load or force that will cause the equipment to break, but they don't consider whether the equipment is being used correctly by the climber or the strength of the rock.

For this reason, it's extremely important for every climber to understand how to use climbing gear properly and use good judgment when out in the field.

Always look for equipment that passes the UIAA tests to help ensure a safe climb and long-lasting, durable equipment.

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