Except for the chance to spend a few focused hours catching up on my reading, I just don't like most things about flying: cramped seats, bland food, long lines at understaffed immigration counters, and unnecessary radiation exposure from intrusive security scanners.

One book, however, has changed how I think about flying: Skyfaring: A Journey With a Pilot. Written by Mark Vanhoenacker, a senior first officer with British Airways who flies 747s on long-haul routes, Skyfaring is a meditation on the beauty and mystery of modern flight--and the technological wonders that make it possible. 

It's an inspiring read if you're a frequent business traveler like me, and you often think about what makes those behemoths of the sky get up there--and stay up there.

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Vanhoenacker's writing lends clarity to knotty technical topics pertaining to aerodynamics and airplanes. His style reads more like poetry than prose  in the way that he explains how hefty 747s manage to lift-off from the ground, how they stay in the air, and how they find their way to their cross-continental destinations. 

Here are some excerpts from Vanhoenacker's book that highlight four fascinating facts about flying that are generally known only to pilots:

Fact 1: Altitude is a relative (and uncertain) concept.

Whatever the altitude shown on the screens in front of you in the passenger cabin, whatever is displayed on the altimeters in the cockpit, the plane is almost certainly not at that altitude, because the pressure of air on the earth immediately below you is not known and, even if it were -- from the weather report of a nearby airport, for example -- our altimeters are not set to it.

It was a memorable moment of my training when I realized that a plane flying at 35,000 feet is unlikely to be at the same altitude as another plane, elsewhere in the world, whose altimeters also show it to be at 35,000 feet.

Fact 2: Pilots measure speed in four different ways (and none of them yield the same number). 

In the sky, there are four important concepts of speed. First is indicated airspeed. This is best imagined as the speed at which you'd guess you were traveling if you stuck your hand out the window and felt the air against it.

In all but the most limited circumstances, indicated airspeed bears little resemblance to true airspeed -- your actual speed relative to the air mass around the plane. 

Third is ground speed, your speed over the earth, which is perhaps nearest to our terrestrial understanding of motion, though it is irrelevant to everything about an airplane that has to do with the air, and often differs from indicated and true speed by hundreds of miles per hour.

Finally, there is Mach, the true airspeed of the plane relative to the local speed of sound.

If you ask pilots how fast their plane is going, they might pause before replying. They might say it depends.

Fact 3: Pilots fly on magnetic headings -- even though a 747, like most airplanes, has no magnetic inputs.

Most of the time, we fly on magnetic headings. The reason for this is largely historical. In the early days of aviation, pilots -- like birds and mariners -- only had magnetic directions to choose from, because they only had magnetic compasses.

Yet the heading display on a 747, like that on most airliners, has no magnetic inputs. It is a surprise to new pilots, who have flown and studied and been tested on the vagaries and inherent errors of magnetic compasses, to realize that on a typical modern airliner there is nothing to sense the magnetism on the earth and feed it into the computers that generate our display of magnetic headings. There is only one magnetic compass onboard -- a forlorn, technically isolated backup device that is never used in normal flight.

To display magnetic headings without using a magnetic compass, the plane consults its map of magnetic variation.... In other words, the world's airliners fly on magnetic headings derived from a preloaded map of magnetism, rather than actual compasses.

Fact 4: The map pilots use to navigate in the sky looks very different from the map we use to find our way on the ground.

The sky is divided into administrative divisions of airspace. These divisions aren't straightforward; there are various, often overlapping, kinds, and often the name of a region on a map is not the same as that used to identify the controllers and radio operators we speak to there. The sky regions may be roughly equal to an earthly place you have heard of, or smaller, or much larger.

Salt Lake City covers parts of nine states, from southern Nevada, north over the Great Salt Lake itself and its city, to the Canadian border, which it meets between the sky states of Seattle and Minneapolis.

Perhaps the best-known volume of air to most European pilots, Maastricht covers the higher airspace of Belgium, the Netherlands, Luxembourg, northwest Germany, and certain nearby areas, a whole and peaceful dominion that rises over some of the continent's historically bloodiest borders.

 

Acquiring a better understanding of the mystery of modern flight might not make all of the annoyances of air travel go away. But it might make them just a little more bearable.