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NASA's Aeronautic Safety Program is a program designed to help pilots fly their planes safer.

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To know where storms are so they can fly around it.

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To be sure they know where other planes are so they won't crash with them.

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To understand where the ground is so they won't have difficult emergency landings.

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It will help them maintain the planes better so they won't have engine problems,

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they won't have cracks in the wings, they won't have electronics that fail.

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It will help them see through storms and see through the night and it will make airports much safer.

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Music

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Hi, I'm Van Hughes for Connect.

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You know it seems everybody is always talking about the weather.

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I mean anyone can easily adapt to the change in weather conditions.

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There are many variables that help define weather like the sun, the rain, and even the snow.

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But weather can also influence a lot of things in our everyday life.

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In this program you will learn how weather impacts air transportation

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and the actions taken by pilots and ground operators in preparation for planes to fly during inclement weather conditions.

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You will see two examples of NASA and FAA research that is currently being conducted

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to address weather related air travel concerns.

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For example, the F-106 behind me was subjected to lightning strikes by NASA researchers

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to study how lightning impacts airborne aircraft.

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That's pretty cool.

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In this program you will be asked to participate in a math based problem

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and experience first hand a demonstration of how weather can impact air travel.

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At any time during this program when you hear this

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and you see that on the screen, write down the Connect web address.

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By using an internet accessible computer you'll be able to access NASA and FAA researchers

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and hear from them their perspectives to questions presented throughout this program.

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You'll also find other experts highlighted including meteorologists, pilots, and even kids like us.

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But for right now, join us as we begin a new season of Connect.

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Music

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The United States is subjected to some of the world's most diversified weather conditions.

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During the course of a normal year, our country may experience plus 100 degrees temperatures,

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jungle humidity, negative 30 degrees cold, severe drought conditions,

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as well as being the world leader in tornado activity.

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Not to mention an occasional east coast hurricane.

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As our transportation system has expanded, so too has our tendency to commute on a daily basis,

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to work and recreational events.

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The potential for weather to complicate our lives is therefore also increased.

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Aviation, perhaps more than other readily available modes of transportation today,

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is strongly impacted by weather conditions.

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Did you know that 75% of all airport delays are related to weather?

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In 1996, the estimated price tag for weather related delays, diversions, cancellations,

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and unexpected operating costs was $2.1 billion.

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The U.S. government invested approximately $830 million in aviation weather efforts during 1997.

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As the magnitude of these numbers indicate, ensuring weather related safety and efficiency of flight

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has economic and human life ramifications to business and traveling public communities.

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Weather has a continual impact on both the safety of aircraft in flight

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and the efficiency of operations throughout the national airspace system.

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To complicate things even more, air traffic is projected to triple over the next 20 years.

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More planes and people in the air fly longer distances more often.

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Imagine what a weather delay will mean with more air traffic.

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Talk about a traffic jam.

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How important is weather information to your daily activities?

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How well do you understand the weather system and the interaction of the various elements on the daily forecast?

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But most of all, how might weather in one location affect your planned travel to a different region?

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Today's meteorologists have the tools and advanced technology

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to explain complex weather phenomena in a way that's simple to understand,

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thanks largely to satellite information and computer-based modeling.

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Dennis Smith of the Weather Channel in Atlanta, Georgia,

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has offered to explain and help us understand the fundamentals of weather.

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Dennis?

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Thanks, Van.

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As many of you know, the Weather Channel provides 24-hour weather information

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both from a national and international perspective.

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Our meteorologists constantly monitor and update weather information.

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Now today, we're going to fly through some basic weather concepts

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and talk a little bit about winter weather, which can cause some problems for aircraft.

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To explain how our weather occurs, we must first travel out past the boundaries of our atmosphere,

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93 million miles away.

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Our sun emits visible and invisible energy that we call solar radiation.

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Radiation from the sun travels through the Earth's atmosphere,

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heating the air, the land, and the water it contacts.

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The Earth's surface absorbs much more radiation than the atmosphere.

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This means that the sun heats the ground, and the ground heats the atmosphere.

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Not all parts of the Earth are warmed equally.

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Regions around the equator receive more concentrated solar radiation

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than do areas around the poles.

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This means that the equator is warmer than the poles.

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Temperature differences also result because land and water do not absorb solar radiation equally.

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Because air moves, warm air and cold air are constantly mixing in the atmosphere.

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This mixing not only evens out the global temperature contrast,

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but results in the various weather conditions we see every day.

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If solar radiation penetrates all layers of the atmosphere,

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it is nearly all weather occur in the lowest layer, the troposphere.

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The troposphere is warmest near the ground and cooler the higher you go.

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This temperature pattern is favorable for the development of vertical air currents.

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Relatively warm air tends to rise, and relatively cool air tends to sink.

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As warm air rises in the atmosphere, it expands and cools.

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As air cools, clouds can form, and precipitation can fall.

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Warm air rising causes less pressure to be exerted by the atmosphere.

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Lower air pressure.

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Cool air falling causes more pressure to be exerted.

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High air pressure.

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As warm and cool air flow from one region to another,

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pressure changes, and so can the weather.

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When air pressure falls quickly, it usually means that stormy weather is approaching.

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That's the result of a low-pressure system.

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When air pressure rises, fair weather typically results.

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That's the result of a high-pressure system.

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Wind is another byproduct of changing air pressure.

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Winds flow because of the pressure differences in the atmosphere.

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Air moves from the areas of high pressure to areas of low pressure.

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Winds spiral inward toward low pressure, causing a piling up of air,

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forcing air to rise and cool, forming clouds and eventually precipitation.

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Around high pressure, winds spiral outward, promoting sinking air and fair weather.

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Okay, now, while you're soaking up that information,

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let's think of something a little bit more fun.

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Snow days.

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When you think of winter, is this the picture you see?

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Snow, snow, and more snow.

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But there are other types of winter precipitation.

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The type of precipitation that falls during winter depends on how warm air moves

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over a layer of below-freezing air.

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A good place to start is with sleet.

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Sleet is frozen precipitation falling as ice pellets.

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These ice pellets form when snowflakes pass through a thin layer of warm air and melt.

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They refreeze into ice pellets as they fall through another layer of colder air close to the ground.

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Freezing rain is made of water droplets that fall to the Earth's surface

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and freeze upon contact with the ground or objects near the ground.

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For freezing rain to develop, cold air close to the ground needs to be shallow.

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The rain doesn't have time to freeze into ice pellets,

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but upon contact with frozen objects, it turns into ice.

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Snow is frozen precipitation in the form of a six-sided ice crystal.

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Snow is produced in clouds where water vapor changes directly into ice crystals

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that remain frozen as they fall to Earth.

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Snow will fall when temperatures remain below freezing from the clouds to the ground

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or when a very shallow layer of above-freezing air is present near the ground.

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Winter weather can be a lot of fun to play in,

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but it can cause some problems for us when we try to get out and travel,

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either by foot, by car, and especially by air.

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Now that you have a better understanding of weather, here's a question for you.

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Weather reports of snow are typically based on visibility.

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Snowfall is considered heavy when an observer cannot see very far through the flakes,

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but visibility is not the critical element for the meteorologist interested in aircraft operations.

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What do you suppose is the main issue that is considered

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in looking at snowfall from the perspective of aviation?

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Back to you, Van.

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Thanks, Dennis.

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We have just seen the weather channel for people,

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but can you believe that airplanes need their own weather channel?

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To tell us more about the aviation weather channel

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is Tom Van Meter of the Federal Aviation Administration.

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Thanks, Van.

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Pilots need to have a continual awareness of the changing nature of the atmosphere on their route of flight

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in order to be able to react to changing weather conditions in a safe, efficient, and timely manner.

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It is the job of the weather coordinators here at the FAA's Air Traffic Control System Command Center

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to provide aviation weather information to operational aviation decision makers,

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such as traffic management and severe weather specialists here at the command center,

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along with the traffic management units and severe weather specialists in the field facilities.

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While the National Weather Service looks at a wide range of weather conditions,

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the information that the weather coordinators are looking for is aviation-related,

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such as icing conditions and thunderstorms,

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that can have a major impact on the national airspace system.

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Weather phenomena such as thunderstorms, clear air turbulence, volcanic ash,

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and severe icing can cause large portions of the national airspace system to be unusable.

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Geographical features and altitude also have an effect on aviation weather.

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Moisture drawn from the Great Lakes can cause lake-effect snowstorms

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to form on the east side of the Great Lakes, while the rest of the Midwest remains clear.

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When icing conditions such as freezing rain occur at an airport,

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ice may build up on aircraft wings, changing their shape

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and adding a considerable amount of weight to the aircraft.

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This change in shape and addition of weight can cause the aircraft to be unable to fly.

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To counter the effects of icing at certain airports, the airport may go into a de-icing status.

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De-icing is a slow procedure in which the entire aircraft is sprayed with a de-icing fluid

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to remove the ice and temporarily prevent additional buildup.

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Because of the time it takes to de-ice an aircraft,

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there is a reduction in the number of aircraft that can depart from that airport.

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When this happens, if a corresponding reduction in the arrival traffic is not made,

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the number of aircraft on the airport will grow

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until there is no longer any ramp space left in which to park additional aircraft.

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This situation is known as gridlock.

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The traffic management specialists at the command center

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monitor the situation at airports in a de-icing status

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and, if necessary, will adjust the arrival flows in order to accommodate the airport's capacity

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and prevent it from going into gridlock.

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When icing conditions aloft impact a large geographical area,

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the traffic management specialists in the command center's severe weather unit

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work with the affected facilities to develop routes around the icing conditions.

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Aircraft that are not equipped for flight into icing conditions may use these routes

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or may divert to another airport to wait until the icing conditions have passed.

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Aircraft that are equipped for flight into icing conditions may fly through the area if desired.

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Consider the weather-related condition of icing.

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Are icing characteristics the same everywhere?

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So let me ask you, how might geographic and atmospheric features

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contribute to icing differences in different regions of the United States?

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So now you know, people aren't the only ones that need a weather channel.

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Consider the dilemma in working in the field of meteorology.

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Unlike other science fields where laboratory tests can be performed under tight controls,

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meteorology has no laboratory except for a vast dynamic atmosphere outside.

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Our friends at the weather channel and the FAA Air Traffic Systems Command Center

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have helped demonstrate the science and art in making weather predictions

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and decisions that affect us on the ground and in the air.

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Hi, I'm Shelley Canright, pre-college officer for NASA and host for the Connect series.

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Thus far, we have been given some basic understanding of weather fundamentals

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and the impact weather has on aviation operations.

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Meteorological conditions, which have been frequent causes of aviation delays,

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injuries and accidents include poor visibility, thunderstorms, wind chill or microbursts,

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clear air turbulence, snow storms, freezing rain and icing.

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In today's program, you will hear from leaders in the federal government

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who have made aviation safety and aviation weather a specific mission.

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Central to this is research.

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It's a key factor in the development and implementation of new technologies

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related to aviation weather.

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And because of all that, you're going to have the opportunity to visit

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some unique NASA facilities and witness groundbreaking research.

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And as you listen to the researchers' stories on their investigations,

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consider these questions.

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What is the relationship between science and technology?

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What is the role of mathematics and mathematical tools in scientific inquiry?

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And what is the value of collaborations and partnerships in conducting research?

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We have already mentioned the many types of meteorological conditions

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that can affect aviation operations.

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For the remaining portion of this program, though,

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we're going to limit our focus on one type, icing.

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Icing can have a profound effect on both the in-flight and ground operations of aircraft.

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Let us visit two NASA research centers that are involved in various icing research studies.

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We'll start our icing travels by visiting NASA Lewis Research Center in Cleveland, Ohio

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and its Icing Research Tunnel.

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Now, this facility is the world's largest refrigerated wind tunnel.

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So bundle up.

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Let's go visit this giant cooler and have a closer look at icing effects on aircraft

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and the icing research being conducted.

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Listen to learn how one measures the effects of ice on aircraft performance.

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Thanks, Shelley.

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My name is Dr. Judy Foss-Vanzanti,

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and I'm standing in the test section of the Icing Research Tunnel.

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Right now it's nice and warm in here, but later on it's going to get really cold.

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All right.

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What this tunnel was built for was to simulate down here on the ground

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what it's like for an airplane to fly through an icing cloud up there.

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We do this by creating a cloud that mimics what you see up there.

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As one of the research engineers, I asked the operators to select five parameters.

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One is the air speed coming past the model.

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One is the temperature, how cold it is, always below freezing.

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Two parameters are about the cloud density, how much water I have in the cloud,

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and also how big each drop size is.

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The final parameter I select is the time that I'll be flying through that cloud.

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I select the cloud conditions.

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I select the model.

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I either select an engine, which provides the airplane forward thrust,

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or I select a wing, which provides the plane lift.

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And I want to see one of three things.

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One is what kind of ice do I grow on my model?

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What does it look like for the given cloud condition?

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Another thing I might want to look at is how to keep ice from growing on that,

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an ice protection system.

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And a third thing I might want to look at is to see how well I can predict

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what the ice shape is going to look like using a mathematical model and a computer.

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All these three functions are done in the tunnel.

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I used this tunnel along with Tom Ratvasky for the tailplane icing program.

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What we did there was to see how ice contamination affects the operation of the tailplane.

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Let's take a look at what the tailplane is and how it affects the aircraft operation.

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What we have here is an animation of an airplane in flight.

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The forces acting on this airplane are the weight, which acts through the center of gravity.

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The upward lift is provided by the wing,

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and the tailplane on the right side of the screen provides a downward lift.

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In equilibrium flight, we've got the following force and moment balances to consider.

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We've got the weight, which acts through the center of gravity,

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which is also the aircraft's pivot point.

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That's always forward of the wing's center of lift.

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Those two forces acting together create a nose-down pitching moment.

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The tail comes in to provide a downward lift.

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As you can see, that's a simple geometry problem.

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The plane acts an awful lot like a seesaw.

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The tailplane icing project that Tom and I worked on investigated the question,

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what happens if you move that wing's center of lift further back?

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How does that affect the tailplane if you've got an ice shape on it?

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We at NASA Lewis Research Center took this information and gave it to the pilots

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so they can make better and safer operating decisions.

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Back to you, Shelley.

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Good science boils down to making as many high-quality observations as possible

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and then analyzing and interpreting them.

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At NASA Langley Research Center in Hampton, Virginia,

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a five-year research program called the Joint Runway Friction Measurement Program is underway.

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This international effort is investigating aircraft losing traction on icy runways.

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This icing research program is having some groovy spinoffs.

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Let's meet with Tom Yeager and learn more about Runaway Runways.

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Thanks, Shelley.

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I'm standing here this morning in our Aircraft Landing Dynamics Facility shop area.

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Behind me you can see one of our test carriages.

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We've got a display here of a landing gear system that we're looking at to evaluate

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from a standpoint of reducing the loads going into the fuselage.

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On my right here is a display showing some of the work that we've done

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to support the Shuttle Tire Program that got started in the mid-'70s

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and has been quite successful since then.

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We've made several modifications to the runway down there

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based on research data that we obtained here

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at our Aircraft Landing Dynamics Facility in Hampton, Virginia.

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We've also done work in modifying the tire design

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and the brake unit that's used on the shuttle

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that's being flown later on this month from Kennedy Space Center.

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We do a lot of work looking at aircraft tread design,

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how the grooves are positioned, and minimize the hydroplaning potential

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that can occur during aircraft landing and takeoff operations on wet runways.

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You're viewing a typical aircraft landing gear tire

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touching down on a contaminated or ice-covered surface.

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And due to the reduced friction capability between the tire and the ice,

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it takes a considerably long time for this tire to spin up

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to a speed that's equal to the forward motion of the airplane.

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We're currently involved in the fourth year of a five-year program

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with a partnership with the FAA, Transport Canada,

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the National Research Council up in Ottawa,

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the National Defense Department out of Winnipeg,

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as well as several aviation organizations supporting this activity

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where we're evaluating aircraft braking performance under winter conditions.

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These conditions include snow, ice, slush, and water.

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And to date, the majority of the tests have been taking place in North Bay, Ontario,

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which is about two and a half hours north of Toronto.

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We've evaluated braking performance of a Falcon 20,

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a de Havilland Dash 8 airplane, an FAA Boeing 727 airplane,

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and a NASA Boeing 737 airplane.

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Coming up in this program, you'll be involved in a classroom experiment

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that will give you a better idea of how the coefficient of friction

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influences the motion of two objects, for example, pavements and tires.

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In our work here at the track facility,

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we've identified the fact that the higher the friction coefficient,

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the shorter the stopping distance is for an airplane operating on a runway

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and the less chance he has of going off either the side or the end of the runway.

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Some of the equations that determine this behavior of vehicles operating on pavement surfaces

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will be explained to you in the classroom experiment,

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and I want to wish all of you good luck in conducting that experiment.

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We've just seen the tip of the iceberg regarding the amazing research,

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researchers, and research tools.

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It makes me wonder, though, what other new technologies are under development

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for reducing icing hazards.

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But you know what? Now's the time to put you to work.

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Coming up is a high school student who has spent the summer at NASA Langley

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in a nine-week mentorship working closely with Tom Yeager.

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John has prepared a special hands-on, minds-on activity,

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which a group of students will demonstrate.

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Following the program, you are encouraged to replicate the same investigation.

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I spent nine weeks in a NASA program for high school students called SHARP.

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Under this program, I had the opportunity to work with Mr. Yeager.

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I learned a great deal about the research being done on runway friction,

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tire designs, and new types of runway surfaces to minimize bad weather effects.

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I have to admit I was a little nervous at the beginning

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just because I wasn't sure if I knew enough math and science

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to be able to grasp the research and to be able to help out

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in the evaluation of the research data.

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But I did okay.

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I found that the math I had taken in middle school and high school

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gave me a good foundation that I could build on.

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With the help of two undergraduate students that I worked with during the summer,

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Brian and Jonathan, I have a simple experiment that I would like you to try.

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In this experiment, you will investigate how surface conditions influence

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the coefficient of friction between two surfaces.

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Your surfaces will include a ruler, sandpaper, and objects found in the classroom.

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Now, my friends and I did an experiment similar to the one you're about to do,

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but it was a little more complicated and involved a little more math.

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This experiment has been recreated on the Connect to Plane Weather website,

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so you might try this with your friends or your family following the program.

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Enough said. Let's get started.

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The math formula you will need in doing your experiment looks like this.

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Friction coefficient equals height divided by length.

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The following materials were collected for our experiment.

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Three metric rulers, at least one of the rulers had to be plastic,

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a sheet of sandpaper large enough to cover a ruler,

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and four objects to test, a rubber eraser, a large metal paper clip,

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a plastic film canister top, and a small dice.

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John helped us identify the dependent and independent variables for our experiment.

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The independent variable, which is what we would be changing,

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is the ruler surface.

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We used a plastic ruler to simulate a smooth runway surface,

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and then a ruler covered with sandpaper to simulate a rough runway surface.

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The dependent variable for the experiment was the classroom object.

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Before doing our test, we talked about how each object was alike and different.

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We shared ideas on how the surface condition,

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which we would slide these objects across,

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might affect the friction force of each object.

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We hypothesized about the effect the surface change would have on the objects.

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Here are our test procedures we followed.

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One metric ruler we identified as the test base and labeled with the number one.

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It would be used to measure the length.

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A second ruler labeled with the two was held upright for the test.

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We would measure the height from this ruler.

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The third ruler labeled with three was plastic and would represent the runway.

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One person handled the runway ruler.

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One person held the height ruler.

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A third person was responsible for reading the height and base measurements,

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and the fourth person was responsible for recording data.

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In running our two surface tests,

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we were interested in collecting the height measurement for the vertical ruler

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and the length measurement from the base ruler

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at the point when an object began to slide down the runway ruler.

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We tested each object three times on both a smooth and rough surface.

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The smooth surface was the back side of our plastic ruler.

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The rough surface was the sandpaper attached to the ruler.

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Here is a diagram to show you how the experiment worked.

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Each test object was placed at the end of a ruler,

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and then one end of the ruler was slowly raised.

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We stopped raising the ruler when the object started to slide down the slope of the runway

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and then took our measurements of height and length.

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Now that we have finished our testing, we are ready to look closely at our data.

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First, we will calculate the height and length average for each object on each of the surface types.

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Height

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Length

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Height

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Length

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Height

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Length

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Length

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Height

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Length

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Using these averages, we will apply John's formula to find the friction coefficient.

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That formula is friction coefficient equals height divided by length.

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Now we are ready to answer our question.

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What effect does surface condition have on the friction coefficient between two surfaces?

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Well, this is our experiment, and we leave you with a challenge.

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What other variables can you think of to test in this experiment?

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Okay, gang, you've received your challenge.

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Complete your own runway traction experiment and then do further tests on different surface conditions.

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As we bring this program to a close, let me remind you to check out the CONNECT website

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for responses from a variety of experts to questions posted throughout this program

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and also to participate in an online friction experiment.

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Let me slide things to the end now for some closing comments.

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This is Shelly Canright for CONNECT, connecting you with real science and with real scientists in near real time.

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Take it away, Van.

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Thanks, Shelly. I hope you all have a plain understanding of plain weather.

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I know I sure do.

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Join us for other CONNECT programs.

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Simply access our CONNECT website for information and program availability.

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So until next time, stay connected.

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♪♪♪

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♪♪♪

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♪♪♪