NARRATOR: They're
where the rubber meets the road, the crucial
interface between land and sky. They are the main drag
in big city airports and a thin ribbon
of hope in the bush. They can be three miles long or
as compact as a football field. Now, "Runways" on
"Modern Marvels." [theme music] The runway. It just might be the most
underappreciated piece of infrastructure in America. Bridges and tunnels get
all the oohs and ahs, but runways are the backbone
of the aviation industry, which is the backbone of the
transportation industry. Every day, 175,000 aircraft
take off and touch down on runways in the US. Everything sort of
revolves around the runway. Every pilot that goes out there
trusts the airport proprietor, air traffic control, that they
have 9,400 feet of absolutely the safest runway that
we can provide for them. BOB DAUGHERTY: Runways aren't
really the most glamorous of structures,
certainly, but they do form the basis of the
air transportation system. I mean, you really have to get
down and get up from somewhere. So they are, of
course, very important. DAVID HENDERSON: I've
been flying for 20 years. The first thing you have to
learn is how to take it off and how to put it
back on the ground. All the rest of your
mission you learn later. But if you can't get it in the
air and get it on the ground, you can't go any
further than that. NARRATOR: Before
we go any further, let's make one thing
perfectly clear. Runways are never,
under any circumstances, to be confused with ordinary
roads or even the interstate. In terms of layout,
construction, and design, the runway is to the
interstate as the interstate is to an urban sidewalk. And for the same reason. Sidewalk, highway, and runway. Each have to handle
progressively greater loads of stress. The runway must accept
tremendous forces on it. The landing of a 500,000
pound aircraft going in excess of 140 miles an hour
puts a tremendous strain on the runway
structural limitations. So the runway has to be elastic. It has to be built in such
a way that it can accept this huge weight and
accept the heat that's generated by the stopping
aircraft and not deform. So it's very complicated. NARRATOR: The complications
begin in the planning stage. Before any paving is
poured, a host of ground, subsoil, line of sight, and
wind studies must be conducted. Planes need wind to
take off and land into, and surveyors have to draw
up a wind rose, a map of wind patterns that will dictate
the layout of the airstrip. A precise assessment
of surrounding terrain, including mountains
and skyscrapers, is also critical to make sure
that planes will have room to clear such obstacles in time. Runways are made of
either concrete, which lasts longer and has less give,
or asphalt, which is cheaper but requires more maintenance. Deciding what kind of finish to
put on the asphalt or concrete is a crucial call. That's because runway slickness
caused by everything from rain, snow, and ice to oil to tire
skid marks in the touchdown zone is a huge concern for
everyone from tire and plane manufacturers to NASA
to the FAA, all of whom have conducted extensive
runway weather and skid tests. If you think driving the
freeway in a storm is dicey, imagine braking
through dense clouds about 10 seconds before
hitting a snow-covered runway at 160 miles an hour. This hydraulic sled track
at NASA's aircraft landing dynamics facility in
Hampton, Virginia, is used to simulate high speed
landings in torrential rainfall of up to 40 inches an hour. It was here in the 1960s
that researchers came up with an invaluable weapon in
the fight against runway skid. Grooving, creating
narrow runoff canals in the paving through
which water can drain, is a simple but revolutionary
idea that has changed the look and texture of runways. As the airplane
operating speeds increased, they couldn't get rid of
the water fast enough. And hence there would
be a pressure build-up that would lift the tire off
the pavement, much like a water skier. And we felt that if
we added channels to get the water off
of the runway quicker, that would help
solve the problem. NARRATOR: Grooving is now
used on 800 runways in the US and on thousands of miles of
highway throughout the country. In case grooving fails, some
airports, especially those with runways that abut
large bodies of water, have adopted a last line of
defense against runway skid. This Styrofoam-like bed
developed by the FAA was installed in 1998 to keep
planes at New York's LaGuardia from sliding into Flushing Bay. Clearly, runways have come a
long way since the early days of aviation, when planes were
so light that they could touch down and rumble to a stop
on farms and meadows. JIM BUCKLES: The typical
runway has actually evolved from a grass field. And if they were really
pressing for efficiency, they mowed the grass. But sooner or later,
as aircraft evolved, they found that the grass
caused additional drag on the wheels of the airplanes,
so they went to bare dirt surfaces. NARRATOR: Dirt was better, as
long as the skies were clear. But landing on dirt in a heavy
rain was a risky proposition. JIM BUCKLES: If you were
the unfortunate victim that was the first lander, and you
didn't know what the condition of the field was, and your
wheels sunk into mud up to the hubs when you were still
going 40 or 60 miles an hour, it could really be disastrous. NARRATOR: The next logical step
was the paved runway, which was little more
than a paved highway and first appeared at
the end of the 1920s. Made of concrete, this
revolutionary advance enabled pilots to make
all-weather takeoffs and landings at any
time of day or night. Until the 1930s, many smaller
airlines landed on water. One of the first
passenger airlines was a seaplane service in
St. Petersburg, Florida. Flying boats, as
they were called, had a smooth,
reinforced underbelly and needed just a few
hundred feet of calm sea to land and dock. But landing on water-- in
effect, a moving runway-- was full of hazards,
and many lives were lost in the
'30s when pilots dipped their wings
into high waves and tumbled to destruction. By the end of the decade, water
had given way almost entirely to concrete. LaGuardia, the first
major airport in the US, was built in 1939 and boasted
two landmark runways, each nearly a mile long. But even that wasn't long
enough for the new generation of bigger, heavier
planes spawned by World War II and the
ascendancy of jets in the 1950s and '60s, which doubled the
weight of previous planes. Overnight, runways, too,
would have to double in size-- jet age runways for
the new jet age. The jet age of the 1960s turned
air traffic into mass traffic and triggered a revolution
in airport and runway design. Dulles International was
the first jet age airport in the US. Cleared for takeoffs in 1962,
Dulles boasted three runways, two of which stretched out
an unprecedented two miles. The 1960s were a boom period
for runway construction. Old runways had to be
extended and widened, and new runways had
to be built to handle the increase in traffic and the
immense stresses of the latest jets. Laying down a thick
coat of concrete for a two-mile runway that was
with shoulders nearly as wide as a football field
was no small task, and runway contractors were
quick to adopt slipform paving, a streamlined technique
developed by the highway industry, as the preferred
means of tackling the job. With slipform,
paving is continuous. The wet concrete is dumped in
front of the paving apparatus, where it is churned and then
shaped into a solid slab a few yards away in the rear. The paver moves a foot
and a half a minute, or about 10,000
feet in five days. Keeping the process going is
all-important, since any stop risks a bump in the runway. Because slipform uses a
very stiff mix of concrete, the paving can be laid out
without fixed side forms to hold the wet slab in place. This runway, constructed in
Atlanta's Municipal Airport in 1969, was laid out in 25
foot wide, two mile long strips. Six strips were laid
side-to-side to complete the job. Unlike today's runway mixes,
which can be ready for traffic in one to three days, 1960s
concrete usually took two weeks to set. In order to toughen the runway
for the punishment to come, a steel mesh was placed between
8 inch layers of concrete. The mesh spreads the stress
loads of landing craft. Dowel bars were
also strategically placed to connect
adjacent slabs. The 21st century so far
is still the age of jets, and runways today
are constructed in much the same
way as in the 1960s and to the same
general specifications. They range in thickness
from 6 to 50 inches, depending on the weight and
intensity of the traffic they'll have to bear. But they are not evenly
thick throughout. THOMAS J. YAGER: The
biggest loading, of course, is in the touchdown
areas, roughly 2,000 feet on either end of the runway. That can amount to several
hundred thousand pounds in a relatively small
tire contact area. And hence they normally have
the thickness of the pavement in those touchdown areas
greater than what they have in the middle portion. NARRATOR: Creating
a smooth grade is critical in
runway construction since planes landing
at high speeds will turn even minor variations
into a roller coaster ride. The string line technique
in which surveyors set up a line on either
side of the paver to trace the desired grade of
the runway is the most popular. A wand from the paver touches
the line, measuring changes in elevation, and the
machine hydraulically adjusts the height of its paving
pan to make the smoothest, most even surface possible. A smooth runway
is just one aspect of what makes a safe
runway, and runway safety is an enormous concern,
especially after construction, when the runway is running. That's because ironically,
the time a plane spends on the ground can be one of
the most dangerous parts of air travel. Runway collisions between
planes have killed 49 people in the US since 1990, although
only six since early 1991. And incursions, violations
of runway space by aircraft and other vehicles, hit an
all-time high of 431 in 2000. There were 383 such
incidents in 2001. In fact, the worst commercial
crash in aviation history was caused by a runway smash-up
in Tenerife in the Canary Islands in 1977 when two 747s
collided on takeoff, killing 583 people. JIM BUCKLES: There
are some airports that have what have clearly
become known as hotspots, where repeated incursions, whether
they be pilot deviations, where a pilot made an error, or
a vehicle making a runway incursion or going
someplace on the airport where they're not supposed to. Those hotspots have been
identified on those airports, made a matter of record. And the FAA and the
airport proprietors work really hard as a
team to fix those areas. NARRATOR: Human error
is the main cause of runway incursions. And since the mid-'90s, both
the FAA and NASA have been developing crash warning systems
designed to keep pilots on top of airfield traffic, like
this advanced cockpit display system, created at NASA's
Langley Research Center. The system uses GPS
signals, traffic sensors, and NASA software to create
an electronic moving map that shows and sounds an alert
whenever an incursion is about to take place. CRASH WARNING SYSTEM:
Runway Traffic. Runway traffic. NARRATOR: Another serious
but sometimes subtle danger on runways comes in the
form of rubbish, or FOD, which is the acronym for Foreign
Objects and Debris. Rubbish, chunks of asphalt or
concrete, loose bits of rubber can all wreak havoc in
the engines of a jet. FOD has been a factor in 29
accidents in the US since 1990, seven of them deadly. It was FOD in the form of
a 16 inch piece of metal that had fallen off
another plane that caused the supersonic Concorde
to crash outside Paris in 2000, killing all
109 passengers and crew. The metal punctured the
Concorde's front tire, firing heavy chunks of rubber
into the jet's fuel tanks, which ignited. DAVID HENDERSON: With
our jet engines pushing through so much air, they
act like vacuum cleaners on the front. And if your jet engine
is mounted on your jet so that it's low
enough, it can just pick a rock right
up off the ground and suck it through the engine. And that, in itself,
causes a lot of damage. Objects must be attended to
at all times at an airport day and night because, frankly,
the pilot cannot see it when he lands. It is simply too small,
and the landing evolution is too quick for a pilot to
be able to discern objects on the runway. NARRATOR: Many airports use
special suction vehicles that can pick up pebbles
and loose turf when they conduct FOD sweeps. In between, inspectors make
daily runs across the airfield, eyeballing for FOD. But they have to
be quick about it. With planes taking off and
landing every two minutes, there's not a very large
window of opportunity before the inspector himself
becomes a piece of FOD We're going about
100 right now. We're nearing the end
of the runway here. Everything looks
good up until now. OK, runway inspection
is complete. [birds calling] NARRATOR: One of the most
dangerous, common, and least publicized hazards to runway
safety is posed by birds. Meet Elvis, a falcon
that patrols the skies around McConnell Air Force
Base in Wichita, Kansas, keeping the airspace
safe for planes by terrifying other birds. Falcons are very effective
on some species of birds, especially these smaller
birds that are out here. Gulls. They all recognize him
as a natural predator, and they all just
leave the area. NARRATOR: A handful of airports
have resorted to falcons, including JFK, which has
one of the most serious bird problems in the country and
employs no less than 15 falcons to help clear the skies. McConnell, which sits
beneath a major migrating route for geese, ducks,
and other waterfowl, has about 100 bird
strikes a year. Overall in the US, no less
than 43,000 bird strikes with civil aircraft have been
reported since the FAA began keeping records in 1990. Officials believe that most
bird strikes are unreported and that the actual number
is five times that high. Total damage from bird strikes
to commercial air carriers each year worldwide
is $1.2 billion. Every airport that has
a birds in the vicinity must contend with the
likelihood that birds will fly through the
operating airspace and present a hazard to aircraft
on landing and approach, either by being
ingested in the engine or striking the aircraft
windscreen or surface and causing a deformity
and damage to the aircraft. NARRATOR: There are many
reasons for the dramatic rise in bird-plane collisions
in recent years. For one thing, jet engines
are more powerful than ever and can suck up
just about anything that crosses their path. They're also quieter
than ever, making it harder for birds to
detect aircraft and get out of their way. For another, the population
levels of many once-rare species have exploded in the
US, especially around marshland and open fields-- just the kind of terrain that
airports frequently border. 90% of all bird strikes are with
birds protected by federal law, like red tailed hawks, Canada
geese, and sandhill cranes. DAVID HENDERSON:
Probably the most significant in terms
of damage are the ones that go into the engines. We took a bird in
one of the engines, and we were too far
down the runway to stop. So we went on around and
came back and stopped only to discover upon shutdown
about a quarter of a million worth of damage to the blades. And now, that's significant. What was significant to me
was that the engine was still running. And I was happy with that. NARRATOR: The bird strike
problem is so serious that both the military
and engine manufacturers have been testing aircraft since
the 1970s, firing dead chickens and other fowl at windshields
and into the engines of new jets. The military won't buy
an F-16, for example, unless it can withstand a
direct hit from a 4 pound bird at 550 knots. The US Department
of Agriculture, meanwhile, has an
entire research facility near Cleveland dedicated to
coming up with new weapons to wield against birds. This laser holds some
promise, nudging birds gently out of harm's
way with a beam that birds are afraid to cross. As do these
high-intensity pulsating lights that could soon be
fixed to the wings of aircraft. The lights would
scatter birds just quickly enough for
planes and jets to make it through
without a strike. Until the new tools are
available, falcons like Elvis will continue to play a
crucial role at McConnell and other airstrips. FALCONER: These birds basically
establish their territory out here. If they're flown every day, the
resident populations of birds here start thinking,
well, there's a falcon that lives out there. And so they
subsequently stay away. He costs about $1 a day to feed. He's about anywhere from
$1,000 to $2000 to buy. There's a lot of hours
of time and training that go into getting
him where he's at. He's only flown out here for
a little over a month now, so he's just getting started by. Within another two months,
he'll be cooking out here. He'll chase everything in sight. NARRATOR: Helping
Elvis at McConnell is an English
setter named Pepper. Her job is to flush birds
out of the grass that grows around the airfield. FALCONER: They get along great. Pepper's a good girl. She loves it out here. She could run all day. She never gets tired. Elvis, on the other hand, is
a little more temperamental. They were raised together
and just get along fine. NARRATOR: Bird strikes are
such a serious and escalating problem that one entrepreneurial
falconer in Canada has developed a fully
functioning falcon robot that could be cheaper than live
birds since it doesn't have to be trained or maintained. Robofalcon can fly
for 8 to 12 minutes, has a wingspan of between
4 and 9 feet and a wing beat rate of 3 and 1/2
to 7 beats per second. JFK, among others,
has auditioned the mechanical predator,
which comes in five sizes, costs between $6 to
$10,000, and could one day make all the difference in the
war for air space between birds like this and birds like this. Some of the most fascinating
and unusual runways can be found on America's 12
aircraft carriers, floating airports that can race to any
hotspot in the world at over 30 knots. These behemoths carry a
fleet of up to 80 planes, but their runways are
just 400 feet long, stretching out across barely
half the deck of the aircraft carrier. Space, to say the
least, is at a premium. We actually take an
entire city, a city at sea, an airport at sea,
and we condense it down into that ship,
which is 1,100 feet long. And it's quite an operation. It's a real ballet of things
going on all at the same time. NARRATOR: Aircraft
carrier runways aren't long enough for jets,
which weigh up to 65,000 pounds, to lift off
on their own power, so they have to be
catapulted into flight. Each carrier has four
steam-powered catapults, which attach by way of a
slide track on the runway to a T-bar on the plane. The hydraulic engines
that power the catapult are below the runway and
weigh a million pounds apiece. JUSTIN COOPER: Each one
is capable of launching an aircraft from 0 to 150 miles
an hour in under two seconds. The catapults are 300 feet long
and are comprised of two steel cylinders with two 2,500
pound pistons inside. These catapults can create
an amazing amount of force and will launch the aircraft
off the end of the flight deck regardless of the fact that
the engines are on or not. ROBERT GILMAN: Your head is
back against the headrest because the G-forces
will take your head and put it back
against the seat. And then as soon
as you're airborne, you kind of get this pause
because now the acceleration has stopped, and now
the only thing that's driving the airplane forward
is the aircraft's two engines. NARRATOR: Landing
on a runway at sea is even more hair raising,
a kind of controlled crash at very close quarters. Once again, the runway
is too short for a plane to land in a
conventional manner. Instead, a hook on
the tail of the plane has to catch one of four
arresting cables that are stretched out across the deck. ROBERT GILMAN: It is a pretty
violent stop when you're going from 140 miles an
hour down to zero in a matter of about 450 feet. One of the training airplanes
I flew when I first started flying, you would get black and
blue marks right here when you caught the arresting
gear and your body wants to keep flying
forward, but the airplane is going to stop when
you caught a wire. NARRATOR: Making the
landing even more violent is the fact that
these pilots have to gun their engines on
touchdown, just in case they miss the wire and have to stay
airborne for a second go-round. They also have to land
exactly on center line. The lateral margin of error for
these runways is just 5 feet. Any more than that
and the larger jets could clip the wings of
an adjacent jet readying for takeoff. Oh, yeah. Did we forget to mention that
these pilots have to do all this with a moving target? JUSTIN COOPER: We need a minimum
amount of wind over the flight deck. However, we're frequently
out in the Persian Gulf, and there's no wind at all. The carrier has to
create that wind, so the carrier will be
going 25, sometimes 30 knots through the water. From the perspective
of the pilot orbiting overhead the carrier
in preparation for landing, he's looking down,
watching the carrier cruise through the water at 25 knots. It almost looks
unreal that he's now going to land that plane on it. You can imagine the type of
precision it takes to fly that and then when they come out
of the fog or the clouds, see the carrier to make those
last few corrections precisely and land safely on the ship. NARRATOR: Not
surprisingly, the pilots don't always manage to land. The average success rate for
catching a cable is about 90%. Sometimes, pilots catch the
wire, but the hooking mechanism itself goes awry, which
is why the Navy is always interested in testing
other specialized landing gear, like this arresting web. The idea of rigging
of military vessels so that you can
launch planes at sea goes back to the earliest
days of aviation. A daredevil pilot flew a
biplane off a warship in 1910, and a decade later, the US
Navy converted a coal ship with a wooden deck into
the USS Langley, America's first aircraft carrier. Planes of the period were light
enough to launch off the deck without the use of catapults,
although launching devices were introduced in 1915. But arresting cables were
critical from the start in bringing aircraft to a stop. The first steam catapults
were tested in 1934, and they were barely powerful
enough to keep planes aloft until they could fly
under their own power. By the start of World
War II, aircraft carriers were devastating war
machines, each one packed with a fleet of bombers. And they played a critical
role, especially in the Pacific. The Cold War spurred the
development of aircraft carrier technology, and steam catapults
capable of launching jets were introduced in 1954. By now, America's
airport on the ocean was a forbidding symbol
of power and reach. Although there were
occasional failures, like this botched landing on
the carrier Essex in 1956. Keeping those failures
to a minimum today has a lot to do with
paying constant attention to the surface of these
cruising airstrips. Skid problems are
a huge concern. More so than on
conventional runways, since the aircraft
carrier exists in an all-wet environment that
can pitch and roll at any time. We've seen waves breaking
over the flight deck, 60 feet tall waves, sometimes
where the bow is pitching down plus or minus 20 feet. So we need to have an
environment where the planes can move safely on the flight
deck and provide good traction. NARRATOR: Every 18 months,
the steel-plated runway is resurfaced with non-skid,
a texturized coating made up of metal and sand. JUSTIN COOPER: The application
of this special surface takes weeks to put on. It has to be stripped
down to bare metal. And then once the environmental
conditions are right, we will lay this down with
very specialized paint brushes to ensure that the
grain is correct. And it takes about four
days to cure and make to the required hardness
so this will stand up to the pounding of aircraft
and the tailhook slamming down on the surface. NARRATOR: The slamming of
the tailhooks is incessant. The maximum tempo or rate
of takeoffs and landings on an aircraft carrier is
two takeoffs and one landing every 37 seconds during the
day and one takeoff and landing every minute at night. America's space shuttle goes up
higher and stays there longer than any other contemporary
manned aircraft in the world. But the shuttle, like everything
else that leaves the ground, needs a place to touch down. BOB DAUGHERTY: Now, the runway
itself, of course, was designed to be incredibly flat,
incredibly long and wide because you do have, at the
time the runway was designed, essentially an untested vehicle. And you don't-- it's not going
to handle quite as nicely as an airliner, so you want a
very long runway, very flat, and very wide. NARRATOR: The shuttle actually
has two runways in the US, the main one at Kennedy Space
Center in Cape Canaveral, Florida, and a backup at Edwards
Air Force Base in Southern California. The runway at the
Kennedy Space Center is one of the longest in
the world, 15,000 feet long with 1,000 foot
overruns on each end. That's nearly three miles or
50 football fields end to end. It's also 3,000 feet longer
than the runways at JFK and LAX. The shuttle needs all that
room because its braking system isn't comparable to that
of conventional jets. Jets shift their engines
into reverse thrust to slow themselves
down, but the shuttle doesn't have jet engines. It's launched by rocket
power and glides home, and so it has to rely entirely
on wheel brakes, a drag chute, gravity, and a whole
lot of runway room. NASA has been conducting runway
tests at its aircraft landing dynamics facility in Hampton,
Virginia, since the mid-1950s. Here, the hydraulically
powered slide track can simulate shuttle touchdowns,
testing tires and runway surfaces at the same stresses
as at the Kennedy Space Center. BOB DAUGHERTY: We use a
carriage, a tubular steel carriage, that weighs
almost 60 tons. And to get it up to speed,
we fire a jet of water at the rear of this
carriage and accelerate it from up zero up to 250 miles an
hour in just about two seconds. There's about 20
Gs of acceleration during that process. And then once we get the
carriage up to speed, it coasts down the remainder
of a half mile long runway. And during that time, we
apply the vertical loads that the tire would see
during a true Orbiter landing. NARRATOR: Tires are a critical
piece of the shuttle runway equation, even more so than
with commercial jets, which are actually much heavier. That's because the stress
per tire on landing is much greater for the shuttle. BOB DAUGHERTY: A 747 has four
tires per main landing gear, whereas the Orbiter has
two titles per gear. But because of the
aerodynamics of the shuttle, the tire-- the
individual tire loads go sometimes two to three
times the individual tire loads on, say, a 747. In terms of pounds, you
might see 50,000 pounds on a single tire
on a 747 aircraft. For the Orbiter, you can see
tire load-- individual tire loads as high as 140,000 pounds. NARRATOR: The stress is so great
that the $4,000, 16-ply shuttle tires can be used
safely just six times. In contrast, the $800 747 tires,
which can touch down 250 times. In fact, shuttle tires
are only used once. Why jeopardize a
$2 billion vehicle plus a crew for a $4,000 tire? NARRATOR: Like the tire, the
surface of this runway also has to be able to handle
the phenomenal stress loads of touchdown,
especially in bad weather. Given the higher landing
speeds and the heavier weight per tire, concern about
skidding was so great when the runway was first
built that it was initially coated with an
astoundingly rough surface. BOB DAUGHERTY: The texture
of the runway, when it was originally
designed and built, was the most aggressive,
rough texture of any runway that we're aware
of in the world. It was, and again,
purposefully designed that way to combat rainfall rates as
high as three inches an hour, which would flood any
other runway in the world. This is a cheese grater
surface with really aggressive transverse grooving and
very, very rough surfaces. This is great for wet
runway performance, but it's terrible for wear. NARRATOR: The problem
was the surface was so rough, it was
chewing up the tires, especially when any
kind of crosswind was pushing the tires
against the grain. BOB DAUGHERTY: Within
the first five landings, we would see tires that had some
of their carcass cords showing. There's no other airplane
in the world that would perform a single landing
in relatively benign conditions and yet have wear into
the structure of the tire. NARRATOR: After
many experiments, Langley toned down
the runway surface, coming up with just the right
balance between anti-skid and wear and tear. Because of the extreme
levels of touchdown stress, the shuttle runway has to
be one of the toughest, most stable and crack
resistant runways in the world, which is amazing
considering that it was built on Florida swampland and had to
be solidified with compressed Earth dredged from
nearby canals. That foundation is
topped by a 6 inch layer of soil-cement mixture, which
is, in turn, buried under 16 inches of solid
concrete, all of which is maintained at what
is virtually a 0% grade. BOB DAUGHERTY:
The shuttle runway was built to much higher
standards in terms of flatness and levelness compared
to the average runway at a commercial airport. All of us have seen long
period dips and bumps in those runways. The flatness of the shuttle
runway is pretty incredible. It's approximately 2/10 of
an inch per 1,000 feet, which is very, very flat. And when you consider
that it's in the area that it's built in, sort of a
swampy area with ground motion and so forth, it took quite
a bit to make it that flat and keep it that flat. NARRATOR: Speaking of flat, one
of Langley's worst nightmares involves landing the
shuttle with a blown tire. In 1989, researchers
tackled the question of where to land the shuttle
in the event of a blowout, on the rough concrete of Kennedy
or the softer, wide-open lake bed of Edwards Air Force Base? BOB DAUGHERTY: There's
two schools of thought. One is land on the lake
bed because it is wide open and you do have a lot
of room for problems. But the concern
there may be are you going to dig into that surface
and cause so much drag that you lose control of the vehicle? On the other side of the coin,
if you're on a concrete runway, we've done tests here at our
facility that have demonstrated the fact that you can
adequately control the vehicle. Friction won't be too high. But you're likely to get a
tremendous amount of damage because you're grinding
through your tire, your wheel, your brake stack. NARRATOR: After rigging up
small-scale tests at Langley, researchers decided to stage
a much more realistic shuttle blowout using a Convair 990
with a shuttle tire and landing gear mounted in its belly. BOB DAUGHERTY: The idea was,
in fact, to blow the tire up on purpose-- TEST MANAGER: Keep going. BOB DAUGHERTY:
--and continued the test and drag the wheel and
all the parts down the runway and measure the drag forces
associated with that. TEST PILOT: All right, boss. TEST MANAGER: OK,
keep the reverse on. PILOT: We're on the hook. We're on the hook. Lift the tire. Stop this. Stop this. Stop it. Reverse on. And once it blows up, you see
this tremendous ball of flame behind the aircraft that
doesn't stop until they pick the tire up off the ground. NARRATOR: The flame is caused
by a volatile combination of rubber and aluminum dust
that gets kicked up as the tire and wheel base
scrape the concrete. Aluminum and rubber
just happened to be two key ingredients
of rocket fuel. Despite the damage,
however, the tests proved that landing
on concrete at Kennedy is controllable and
relatively safe, and that's where the shuttle
will touch down if it ever has a flat. Most aviation takes place
in and around urban areas, where runways are hefty
pieces of infrastructure that have been designed and
constructed with great care. For those who like to
fly on the wild side, however, runways aren't
quite so reassuring. Welcome to the Frank Church
River of No Return wilderness in Central Idaho, 4.6 million
acres of canyons and gorges where flying is a thrill and
landing can seem unthinkable. Lori MacNichol has
been flying bush planes in Idaho's backcountry
for 20 years. LORI MACNICHOL: We have over 48
different airstrips that we can land at, and these airstrips are
in the heart of the wilderness. They are cut out of just
the side of the hill. And when you are traveling
across this vast land, which 4.6 million acres is, you are
looking for one little scratch, or a lot of people
say, that postage stamp is where we're going? Each landing area has
some type of gotcha. And it may look great when
you're circling overhead, but when you turn final,
you have to tell yourself that you're committed,
that there's simply no go round here. You have to be
ready, and you never know what you're going to get. NARRATOR: That's partly because
what you're going to get is 100% natural. These runways are made out of
the grass, dirt, and gravel that were found on the site. In fact, it's against the law
to bring outside materials into this wilderness, or even to
move found elements like gravel from one spot to another. Indeed, it's even against the
law to build runways here, and most of these airstrips
date from the 1930s and '40s, when pilots and backwoodsmen
fashioned them entirely by hand, pulling out stumps and
rocks and cutting down trees. They are maintained
today without the use of any mechanical tools that
might disrupt or seem out of place in this
protected environment. Even wheelbarrows are banned. LORI MACNICHOL: Little
bit on the flat side. Looking pretty good. I'm looking at that
spot that I like, lining up at the
end of the runway. NARRATOR: The Soldier Bar
runway in the heart of the River of No Return wilderness is
1,600 feet long and 4,200 feet above sea level. LORI MACNICHOL: Yee-haw. We're here. NARRATOR: The surface consists
of grass and embedded rock. Rubber strips wedged in
by hand act as water bars to prevent erosion
caused by rain. This runway is called Cabin
Creek because it actually rests on a dried-out creek bed
that was painstakingly cleared of everything except the hardpan
gravel on which planes now land. There are thousands
of bush pilots flying into and out of hard-to-access
parts of the US, as well as the
rest of the world. Alaska is still the bush
pilot center of the world, with some flyers bringing
everything from groceries to mail to tourists to otherwise
inaccessible communities and oftentimes landing on
improvised runways made out of packed snow and ice. Florida is another
haven for bush pilots, only here, the flyers specialize
in taking off and touching down on water, much like
aviators did with the boat planes of the 1920s and '30s. Water is surprisingly its
trickiest when it's calmest and the glassy surface
is hard to read. LORI MACNICHOL: You
have no depth whatsoever so that when you set up
your descent profile, you try to focus on
something, you really try hard to have some type
of land or shore in view. But very often, you don't, so
you're waiting for that water. And it's very, very important
to make this landing in quite a stick back fashion. NARRATOR: Bush runways are,
in fact, the most dangerous airstrips in the world. Every year in Idaho alone,
some half dozen pilots die trying to bring
their planes down. But for back country fliers, the
danger is part of the appeal. LORI MACNICHOL: The reason
why we're all driven is because of the challenge of
each runway that we approach. Each and every runway,
with its own set of gotchas and its whole new look. You can go to that same
strip day after day, and it has something
different to give you. And that's what
we love about it. It always keeps us on our toes. NARRATOR: On our toes probably
isn't the way most of us want to feel when we're about
to take off or land in a 747. The runway is one part
of the flying experience that we expect to have
a lot of confidence in, and for good reason. These strips of terra
firma, whether they be made of concrete
or riverbed gravel, are an essential part of
the flying equation, which is the paradox that lies
at the heart of aviation. In order to get up
into the air, you need to have a very
firm foot on the ground. [theme music]
