Prairie Sky: A Pilot's Reflections on Flying and the Grace of Altitude

Ground Reference

46 Ground Reference Last night, like so many nights before, I drew a line on a sectional chart. Fargo, North Dakota, to the Coteau des Prairies, a range of hills just over the border in South Dakota. Seventy-three nautical miles on a heading of 190 degrees from home. I’ve seen those hills a thousand times from the ground. Driving up and down Interstate 29, I’ve seen those hills rise on the western horizon, a pretty break on the flatland prairie, and I know just enough about geology to have wondered—why are those hills there? Today I have a partial answer, and so I want to see them again. I want to see them from the air. I cannot remember what I was trying to find, but while surfing through Wikipedia one night, a picture showed up on the edge of my computer screen. It was a tangent at best. But this was a picture of home and it implied a story, so I spent some time reading. In truth, the Coteau des Prairies is just a pile of dirt pushed up into a moraine by a prehistoric ice sheet. That ice receded . When the next ice came, however, the famous Laurentide ice sheet, the Coteau des Prairies, refused to move. It split the glacier and caused a deeper gouging of the land on each side. The hills are nothing spectacular, remarkable only because they are completely out of place, yet they even show up on the maps of Lewis and Clark (center, top), called the Mountain on the Prairie. What I really want to see today is invisible. From the left seat of a rented Cessna 172, heading south toward those rising hills, I want to see history. I want to see the force of the Laurentide ice sheet moving down the continent, and I want to see the hills split the ice. Imagine the slip of paper in a theater program: “Tonight the part of the very large glacier will be played by a very Ground Reference 47 small airplane.” You could call it a type of situational awareness. I want to know, as richly as possible, where I am. —————————————————— There is a wonderful quote by writer Reg Saner. “Destination,” he says, “is mere pretext for the real business of going to meet it.” The reason we practice and refine the grace of our landings, the reason we calculate wind-correction angles and time between waypoints, is that the joy of holding a machine in the sky is profound. The more we know about the land we’re crossing, the deeper that joy becomes. In summer, the approach to the International Peace Garden airport (S28) is calendar-art beautiful. Prairie farmland gives way to deep-green forest near the Canadian border. Round hay bales and ponds dot the fields heading into Runway 28. It’s an easy landing, and the gardens are worth the trip. The poutine in the café is very good. There is a famous glitch in Flight Simulator here. For whatever reason, in the computer world a giant chasm opens on the far end of the runway, and you can fly nearly thirty thousand feet down toward the center of the earth. There is no such hole in real life, but there is something underground. You 48 Prairie Sky cannot see it from the air, and you cannot see it on the ground, even if you’re looking for it hard. But one look at a gravity map shows this part of the state has some of the densest rock possible. Landing at the Peace Garden, it seems, is landing on the summit of an underground mountain. It makes a difference in the way you understand where you are. The North Dakota Isostatic Gravity Anomaly Map isn’t hard to find. Just Google “North Dakota Gravity Map.” Better yet, Google whatever state you live in. Along the same lines, ever wonder why sectionals sometimes warn about extreme magnetic variations? There is something called an aeromagnetic anomaly map. It all makes a difference. Long Island is a different place if you know the whole thing is a moraine pushed up by a glacier. The Grand Canyon is a different place if you know the Colorado River isn’t cutting down as much as the land is rising up, and the sight out your side of the airplane is more impressive if...