My three week-old moratorium on discussions of maps great circles is hereby suspended. The reprieve is needed in order to hype my new favorite website, Karl Swartz’s Great Circle Mapper. The fact I could spend long hours at this page feeding in random city pairs, mesmerized by the connectorial magic of countless red lines, offers discomfiting insight into the minds of those infatuated both with flight and geography. Nonetheless, I’ve yet to find a source that more adroitly illustrates the shortcomings and fallacies of the average wall map or atlas. Never again will I sigh and stammer when presented with the question, “Why does my flight from Chicago to Hong Kong fly over goddamn Siberia?”
My old answer was a groping dissertation on cartographic projections and how to visualize spheres. My new answer is: because. Mapper can do the rest. It takes only a second: Go to the Paths box and type in “ORD-HKG.” Hit the display button and behold. A few thousand pixels exponentially more useful than any Pilot’s mangled syntax.
In fact, freeze right there, gazing down upon the Arctic (note also the more correctly rendered Greenland, as compared to the monsterized version presented by Mercator et al). Without touching another key, locate California and France. Notice the shortest path between San Francisco and Paris takes you above the southern tip of Greenland. Return to the Paths box and enter “SFO-CDG” to see the actual tracing. This may help avoid incidents like the one a year ago when a group of Paris-bound passengers, watching their route unfold on the bulkhead progress screen, were induced to near panic in belief their flight had been hijacked. It took an announcement from the captain to explain why the aircraft seemed headed for the north pole instead of Charles de Gaulle.
As an added bonus, Mapper gives latitude and longitude coordinates for each airport, as well as mileage totals of all pairings (though somewhat worrying is that teasing disclaimer: “This information may not be accurate…”).
I asked Karl Swartz how Mapper does its magic. “I use software from the PROJ.4 package to do the math,” he tells us. “But it’s just spherical geometry to compute the geodesic, fiddled a bit to adjust for the fact that Earth is not exactly a sphere.”
People who speak of “just” spherical geometry make me nervous, so I kept my mouth shut and let Swartz keep talking.
He points out other goodies available on the site. One of the most intriguing, particularly for those of you looking to dodge an arrest warrant or crumbling marriage, is the Locations feature that automatically determines the most distant earthly airport from a chosen point. If I feed my hometown BOS into the Locations box, (followed by a double click on the resulting data), I’m informed that Margaret River, Western Australia, is the farthest airport I can possibly fly to.
“I’m not sure it has much practical value,” says Swartz. “But I suppose you could use it to settle debates about whether or not you’d end up in China if you dug straight down. Yes, if you live in Argentina.”
Once you’re feeling comfortable, or addiction is setting in, have a look at “SVO-SCL.” Presently there’s no direct service from Moscow to Santiago, Chile, but notice the way this imaginary flight traces two great circles, mirrored arcs on either side of the equator evinced through a delicate figure-S. Yes, the bottom of the world is no less round than the top. Try typing “GIG-SYD” (Rio de Janeiro-Sydney) to view one of the more dramatic southerly crossings. Note the passage over Antarctica enjoyed by those aboard Qantas or Varig on a trip from South America to Australia.
Except maybe not. The shortest distance isn’t always the most practical one, and the beauty of a great circle is often sent zig-zagging by geopolitical frictions, exorbitant airspace fees, and the rulebook of something called ETOPS — restrictions placed on aircraft with fewer than three engines.
ETOPS (Extended Twin-engine Operations) was pioneered by TWA in the mid-1980s, when that carrier, after extensive planning and under careful sentry of the FAA, commenced Boeing 767 service across the North Atlantic, a field theretofore dominated by three and four-engine machines like the 747 and DC-10. Twin-engine long hauls soon became commonplace across vast stretches of ocean, subject to remaining within certain distances of diversion points at all times. Midway Island, for example, in the Pacific. Or Keflavik, Iceland.
Last month in Everett, Washington, Boeing rolled out the 777-200LR. The suffix is for “Long Range,” and this newest variant of the widebody twin is longest-legged commercial aircraft ever built. (Pakistan International and Taiwain’s Eva Air are in line to be first customers). Obviously the stigma of operating great distances on only two engines is a thing of the past. Indeed, US and foreign authorities are reorganizing long-haul stipulations under the more simple, less numerically specific umbrella of “EROPS,” or Extended Range Operations.
No plane ever crashed from ETOPS-related engine trouble, and in essence the restrictions have less to do with crashing than with diverting. High over the middle of nowhere, should a four-engine 747 or A340 suffer demise of a powerplant it can, in the majority of cases, carry on toward its destination or suitable alternate field along the way. Even with a second failure, rare as such occurrences are, the plane would remain adequately flyable. Should a twin-engine jet lose an engine, however, the situation is obviously more precarious and a prompt diversion expected. Thus, it isn’t about ocean, it’s about distance to approved alternate runways. From an ETOPS/EROPS point of view, the vastness of empty desert or frozen tundra is no different from the open sea.
A single unplanned pit stop can incur hundreds of thousands of dollars. For manufacturers, much rides on the reliability of their airframes and engines.
This Q&A is part of a collection that originally appeared on Salon.com. Patrick Smith, 38, is an erstwhile airline pilot, retired punk rocker and air travel columnist. His book, Ask the Pilot (Riverhead) was voted “Best Travel Book of 2004” by Amazon.com. Patrick has traveled to more than 55 countries and always asks for a window seat. He lives near Boston.