The Art of the Chart
Somewhere in those symbols, lines, and colors is all the information you need to fly from here to there.
- By Stephan Wilkinson
- Air & Space magazine, November 1999
I have in my airplane a microchip miracle: a small, expensive, ever-changing, dead-on accurate, utterly magical moving--map cockpit display. Driven by an assemblage of silicon powerful enough to run Rhode Island--well, at least to operate all its traffic lights--the unit sniffs data sent to it by Global Positioning System satellites. It instantly and continuously does the arithmetic necessary to say to me at all times, "Here you are, dummy, right where the little airplane symbol on the map is."
See the little mock-Cessna chugging along over highways, rivers, and radio beacons? See the screen display zoom out to show it crossing all of North America at an imperceptible rate? And then zoom in to make it herky-jerk at 200 mph across my hometown streets? That's what aeronautical charts have come to: green and black pixels on a screen the size of a playing card, doing their best to approximate the basic outlines of the world below.
Frankly, I prefer the old-fashioned way. It uses paper, ink, art, artisanship, and nearly a million tints to produce what pilots call sectional charts.
Sectionals don't need batteries. They won't break if you drop them. They never flash a red light and announce "WARNING: SIGNAL LOST!" They can be consulted on the kitchen table or in the bathroom. And they cost only $7.25 apiece.
Since 1927, pilots have navigated U.S. skies by using paper charts produced by what is today called the Office of Aeronautical Charting and Cartography (AC&C), part of the National Oceanic and Atmospheric Administration and thus a ward of the Department of Commerce. Sectionals began as strip maps showing the landmarks and terrain between basic destinations, the very first of them Moline, Illinois, and Kansas City, Missouri.
In those days, landmarks were roads, rivers, railroads, towns, fairgrounds, and the occasional lighted beacon, and the pace was slow enough that the charts were accompanied by text descriptions of the route, sometimes on the other side of the chart. "People would fly and take notes for the pilots who'd be coming along behind them," says Christo Cambetes, a NOAA staff cartographer.
Today, raging civilization has built cell phone towers, drag strips, domed stadia, airports, dams, skyscrapers, race tracks, power lines, many-spired Mormon temples, parachuting sites, Disneylands, radio astronomy antennas, tank farms, ski lifts, power plants, and a hundred other "cultural features." Today, they're all included on sectionals. Says Terry Laydon, director of the AC&C, "The FAA comes up with the [general] concepts and features to be depicted on the charts, but we develop the standards and then work out the issues--what should be depicted and how it should be presented to the pilot."
"The standards" have been collected in an inch-thick volume that spells out everything from how to depict a kanat (an underground aqueduct with surface air vents) to the symbols for "populated places in ruins," the difference between wadis and sebkhas in a desert, and when a rock that is "bare or awash" is big enough to be shown as a tiny island. Read it and you'll understand why AC&C map--makers all have degrees in cartography: There are 147 symbols for topographical and cultural information alone, with nearly 100 more for purely aeronautical features, and each is specified right down to type face and size, color, and line thickness. And what the cartographers must constantly keep in mind is that all this information has to be made crystal clear to a pilot reading a chart with one hand and flying an airplane with the other.
In 1927, there was no piece of sky that was off limits to aviators. Today, everywhere you look there is airspace that is for one reason or another forbidden to pilots who fly by eye and choose not to have their routing defined by radio and air traffic controllers. There are also no--excuses, absolute--exclusion prohibited areas, the airspace above the White House perhaps the best known of them. There are military restricted areas where practicing dogfighters don't want to run into a Bonanza. There are air defense zones where, if you enter without notice, it's assumed you're a terrorist. There are vast blocks of restricted airspace over many big cities to provide freedom for airliners to maneuver during arrival and departure. There are routes where bombers practice very-low-altitude missions--not strictly forbidden airspace, but you're warned that you might be sharing it with a B-52 on fast--forward down in the weeds. Sectionals show all of these as well.
A typical sectional makes a Manhattan road map look like the scrawled directions to your friend's Fourth of July barbecue. "Yes, chart clutter absolutely is a problem," admits Ronald Bolton, the chief of the AC&C's Aeronautical Chart Division, the group that compiles and continually corrects sectionals. "These are the most complex charts I've ever worked with, and I've been doing this since 1974. We make the best damn charts in the world, and we spend more money checking and verifying them than we do in actually producing and printing them. It's a very accurate product."
I have flown with charts and without--the without largely the consequence of carelessness or overconfidence. But just as those who've been rich and poor say rich is better, I say charts is better. One night, a friend dropped me off at a maintenance shop in New England to pick up my airplane, and sailed away into the starry dark before I realized that I'd forgotten my sectional.
Never mind, this is home territory, I thought. For 33 years I'd criss-crossed the cities and rivers and highways around my home in the Hudson River Valley. Hell, I'll just fly west till I hit the Hudson.
Let me tell you how lonely it feels to be a mote in the sky, suspended above a vast sea of lights--and, worse, areas of utter blackness--with an increasing awareness that you haven't the faintest idea where you are. Had the Hudson River already passed beneath me? Was that city Hartford, or was it Albany? I couldn't pull over and ask directions unless I chanced to see the beacon of an airport. Without my sectional I was a blind person with a 200--mph cane, tap-tap-tapping across the airspace and relying on memory.
I once flew with a bush pilot in the northern Arctic--indeed, we were on our way to the north magnetic pole, and, magnetic compass useless, he kept track of our grumbling old de Havilland Otter's progress with his thumb on a chart that he held in the same hand that held the yoke. He moved thumb and fingers as though he was saying a very slow rosary. Otters don't go very fast, but if he'd dropped the near-featureless map and lost his place, we might as well have landed, parked, and waited for the Mounties to find us.
Charts are security. Charts are essential. Even a cockpit filled with computers doesn't substitute for a map. Some months ago, riding in the jumpseat of an SAS 757 from Oslo to Newark, New Jersey, I was amused to notice that the first officer, sitting behind navigation displays the size of small television sets, not only kept track of our progress on a paper chart but had outlined the route with a yellow highlighter.
In his Washington, D.C. office, cartographer Cambetes picks up a folded sectional and says, "This is a tool." He whacks it again and again against a steel partition. "Now may I do that with your fancy handheld GPS receiver, please? GPS is also a tool, but don't leave the sectional out of your toolbox because of it."
Sectional charts are often taken for granted, yet they are printing and publishing accomplishments of immense complexity, acts of reproduction that approach an art form. Countless private pilots have papered their rec-room walls with sectionals, carefully pasted edge to edge to provide not only colorful wallpaper but a reminder of the enormous span of land that a set of wings can bridge. I don't know of any road maps that have been accorded the same honor. Unfortunately, you need Bill Gates' living room, or at least a wall 40 feet long and almost 20 high, to hang the 37 sectionals that cover just the 48 contiguous states. And there's one more for Hawaii and 16 for Alaska.
A typical sectional is almost five feet wide and more than a foot and a half high, printed on both sides. And like urban commuters who develop the ability to turn the pages of a newspaper in a packed subway car, pilots in cramped and often windy cockpits consider the proper folding and unfolding of a sectional a skill as important as leaning an engine's fuel mixture by ear. Even more demanding is the ability to pick up where you left off when your track suddenly migrates from one side of the sectional to the other. Indeed, each chart has instructions on how to handle that dilemma when you're plotting a course.
The compensation for the sectional's unwieldiness is the immensely satisfying proof of one's progress that comes when you move onto the Denver chart, say, and can fold up and put away the Wichita chart. Or, in the case of a slow airplane and a fast headwind, the equivalent is simply crossing a crease in the map and being able to rearrange the folds.
The base for each sectional--the primary map of the country's physical surface--is created from Department of the Interior Geological Survey 7.5 quadrangle maps, which are the delicately delineated maps that blanket the country in a scale so finely focused--each inch of paper is equivalent to a little over a third of a mile--that in rural areas, every house and barn is depicted. On a sectional, each quadrangle covers an area the size of a postage stamp, and it takes 2,000 of them to make up an entire sectional chart. (An inch on a sectional is just under eight miles.)
With the base established, each sectional is built from, typically, 53 layers of information, each layer a separate transparent sheet, all laid atop the map base. Each contains only the uniform graphics and color that are assigned to it. One layer has nothing but uncontrolled--airport symbols, little magenta circles with at most a runway or two shown. Another has control-tower airports, colored blue, with the runways depicted in scale. Another layer is nothing but man-made obstructions. Another: VOR (Very High Frequency Omnirange) compass roses. Another: yellow "urban tint" denoting built-up areas. Water. Highways. Drainage areas. Mountainous elevations. Radio-frequency boxes. Restricted areas. And so forth, amounting to, in the case of the particularly complex Los Angeles sectional, nearly 70 layers.
Continental U.S. sectionals are revised and reprinted every six months--twice the frequency of British and German air charts, which are generally considered to be in a class nearly as good as those of the U.S.--so the individual chart layers are constantly under revision. (Most Alaskan sectionals are renewed annually.) An updated master goes off to the printer every 28 days, since chart revisions are staggered to spread out the workload.
Changes can be wrought by everything from a private pilot calling AC&C (800 626-3677) with the news that the road west of Middletown shown as two lanes sure looked like four when he flew over it, to a mayor writing to announce that his town had just erected a new water tower and it would be swell if the chart honored it. Says Carl Nixon, chief of the Visual Chart Branch, "One of our best sources of new information is simply people flying around looking out the window. We get one or two tips a day, most of them phoned in."
Wander through AC&C's offices and you'll also see Rand McNally road atlases on many a desk. "We use the best available source of information," Nixon says, "whether it's a road atlas or a newspaper clipping." But this is only the first stage in a chart revision. AC&C never takes anything for granted, whether it's a phone call from a pilot, a letter from an electric company announcing completion of a power line, or even an official document from the Federal Aviation Administration. Everything is double-checked, sometimes by cartographers demanding photo verification.
The ultimate proof is "flight editing." NOAA has a small fleet of twin-engine airplanes--a Shrike Commander, Turbo Commander, and Citation business jet--that fly back and forth, over the ground covered by sectionals, like lawnmowers cutting row after row of grass. The in-house joke is that the pilots are simply scouting for nice places to retire to, but in fact they're checking virtually every item on the busier sectionals. They come back from their mind-numbing missions with notes that eventually are scribed onto the margins of the sectional under revision: "add new tower," "dragstrip still good landmark," "airport north of road," and, as the last of the drive-ins crumble, the frequent "delete outdoor theater."
"I get upset when pilots tell me that they can use an outdated chart for several years," Ronald Bolton says. "We can have 800 changes on a single sectional in one six-month cycle." Still, many pilots resist spending $7.25 per chart twice a year. Which in my case, as a pilot who ranges the occasional thousand miles from home base, means a not--unreasonable collection of 10 sectionals for compete coverage: $145 a year. Dare I upset Bolton? I break down and buy a new set of sectionals only when my prime chart--the New York sectional--wears out from constant use. (But if an FAA inspector ramp-checks my airplane and finds out-of-date charts, I could get the aeronautical equivalent of a ticket. And were I to have an accident, particularly as a result of getting lost, my negligence could be used against me in an FAA enforcement action.)
The Office of Aeronautical Charting and Cartography is on the cusp of change--some of it good, some of it the subject of much contention. For one thing, the Department of Commerce is trying to kick them out. "Commerce says we no longer fit in NOAA, which is primarily an environmental organization," says director Terry Laydon. "The aeronautical charting business started with charts intended to promote interstate aeronautical commerce, which is why I keep saying we belong in the Department of Commerce." Commerce, however, wants the AC&C shifted to the Department of Transportation, where it probably would be placed under the FAA. "We're concerned about that," says Laydon, "because it isn't clear that the FAA will support the non--aeronautical part of our activities, such as printing and distributing nautical and military charts." Laydon sees obvious efficiencies in the consolidation of such production.
If they do go to the DOT, the Aeronautical Charting and Cartography Division will be renamed Transnav--short for Transportation Navigation Services. But this is the least of Laydon's concerns. "We don't have a lot of name recognition anyway," he says. "Our charts are known as 'NOS charts' [National Ocean Survey] or 'Nozz charts.' Nobody calls them AC&C charts."
The positive changes, however, are the AC&C's increasing reliance upon computerization and automation, the goal being the eventual disappearance of the cartographer's traditional tools and techniques. "It's a dying art," says printing specialist Nick Alsop as he demonstrates how corrections compiled from flight editing and other sources are hand--engraved onto huge plastic sheets. "We'll probably see all of our tools in the Smithsonian someday."
At one end of the spectrum are Alsop and senior cartographer Ray Harris, who uses nothing more than a Koh-i-Noor lead pencil, an eraser, and an X--Acto knife to endlessly, laboriously draw the properly shadowed lumpiness of thousands upon thousands of square miles of mountainous terrain all over the United States. Harris uses as his guide an underlay of U.S. Geological Survey topographic contour lines and an understanding of how the land will thus fall, fold, and furrow.
At the other extreme is young cartographer Rick Luzier, who toils at a computer workstation "drawing" a map with a keyboard and mouse--at the time I visited him he was working on a new, almost totally automated terminal area chart. (A TAC is an adjunct to a sectional that shows in large scale a single particularly busy city--Cincinnati, in this case--that has complex air carrier traffic and numerous altitude and airspace restrictions for light aircraft.)
But Luzier's work shows why human input is still important. He calls up from a computer database the chart layer that depicts man-made obstructions. They are magically placed on the electronic map more precisely than any cartographer could, but some so exactly that their symbols obscure more important information, and so profusely that Cincinnati becomes a blur of black. The computer is undiscriminating and, as requested, obediently flags every building over 200 feet high, but only a few of the skyscrapers need representation. "Most of the things we do manually can be automated if we have the equipment," Alsop explains, "but there's no way to put that much symbology on a single sheet without human judgment coming into play to decide what to print and where to put it."
Says John Brennan, supervisor of the Eastern Chart Section, "You can't compromise quality just in the interest of making production more efficient. Automation is certainly the way to go, but we have to approach it cautiously. Once something [wrong] gets into the hands of the pilot, it's impossible to recall it. All the young cartographers here are rarin' to go on this new stuff, but we're being cautious."
Still, the AC&C has a tempting goal in sight as it turns more and more chart symbols, locations, landmarks, airways, elevations, and contours into electronic bits: "a seamless database that will go straight into cockpit moving-map displays without ever being on paper," says Bolton. "After all, we're accurate to within better than one pixel on a CRT screen."
For the old fogeys among us, however, nothing will ever replace the sectional--a "database" that is not only cheap, accurate, portable, durable, and convenient, but beautiful.