Skyfaring: A Journey with a Pilot

by Mark Vanhoenacker

Jet lag results from our rapid motion between time zones, across the lines that we have drawn on the earth that equate light with time, and time with geography. Yet our sense of place is scrambled as easily as our body’s circadian rhythms. Because jet lag refers only to a confusion of time, to a difference measured by hours, I call this other feeling place lag: the imaginative drag that results from our jet-age displacements over every kind of distance; from the inability of our deep old sense of place to keep up with our airplanes. Place lag doesn’t require the crossing of a time zone. It doesn’t even require an airplane. Sometimes I’ve been in a forest, for a hike or a picnic, and then later the same day I have returned to a city. Surrounded by cars and noise and blocks of concrete and glass, I’ll find myself asking, how is it that I was walking in the woods this morning? I know it was only this morning I was in that different place; but already it feels like a week ago. We evolved to move slowly over the world, in sight of everything en route. It makes sense that passing time and changing surroundings share a rhythm, and that as a consequence further or more different places naturally seem longer ago. The differences between a forest and a city are so enormous that the journey between them interposes itself as a chronological jump, a kind of time-hill.

His notion of place lag: when your environment changes rapidly and it confuses you; you feel like more time must've passed between the very different environments.

Mountains above a certain height constitute another division of the world, a separate realm of sky. The altitude above which we are required to wear oxygen masks if the cabin pressure fails is 10,000 feet, and so this rough contour shaped by peaks and an added safety margin forms perhaps the map of the world that a pilot might draw most easily from memory, as if sea level had risen by about 2 miles.

This actually doesn't quite make sense. What does the 10k oxygen mask rule have to do with this? These are where you can't drop altitude in case of loss of pressure to avoid using masks because of high mountains?

Jet streams occasionally produce turbulence, particularly at their boundaries. But often they are so smooth they suggest something like the opposite of their true dimensions. When it’s a little bumpy I remember that I am flying at 600 mph, in air that is moving at 200 mph, yet the plane is steadier than a car on a dirt road. Often the fastest winds are as smooth as glass.

Jet streams are actually quite smooth, esp when fast. It's entering and leaving that is turbulent. Also earlier said that "jet" in jet stream has nothing to do with jets flying that high. It's actually more to do with the shape of the winds, narrow jets of wind.

But there remains a set of disposable maps that cover the world, which are sometimes called progress charts. As a child I saw carbon copies of these mounted in the passenger cabin of the aircraft—the path of the plane, a charcoal-gray zigzag over blue sea and yellow land. I still have one or two that I asked the cabin crew for on those long-ago flights. These charts have space for the date and flight number, and for the pilots to write their names and ranks. Completing a progress chart, I feel as if in another age I would be crouched over a table, in heaving seas, an oil lamp or heavy brass navigational instrument on the table to hold the paper in place. I like to draw the steady lines between distant waypoints in thick green or blue ink, to sweep over countries, mountains, oceans as only a pen, or an airliner, can do. Although we have other, computer-generated maps that show the predominant winds along our route, some pilots still draw the winds onto the chart, along with the forecast areas of turbulence. A pilot who does not wish to waste paper might save the chart for the flight home, plotting the return route and winds in different colors from the outbound ones. But if we ever have visitors to the cockpit after landing, especially kids, we will gladly give them the chart to take home.

There are scratch paper charts of flight path used during flights still. Kids can go up to cockpit to ask for them, pilots often open to handing them over

Fuel cools dramatically during a long flight in the high cold, but it cannot be allowed to cool too much. Typical freezing points of fuel are around minus 40 (a temperature that requires no C or F to follow it; it is the intersection of the Celsius and Fahrenheit scales) or colder. The static temperature of the air outside—the ambient temperature, shown perhaps on the moving map screen—is often colder than this. But the TAT, the experienced, wind-warmed temperature, is much higher. Indeed, nothing suggests the speed of airliners and the physicality of air quite like the fact that if the fuel starts to get too cold, the simplest way to warm it up again is to fly a little faster.

Static air temp outside airplane at cruising is usually well below fuel freezing point, but ram rise (heat generated at leading edge of plane/wings due to air compressing at leading edges) helps warm fuel up. In fact, if fuel getting too cool, speeding up counteracts.

Indicated airspeed, then, isn’t speed in any normal, earth-referenced sense.

Beginning of explanation of indicated vs true airspeed. Interesting!

Ground speed, though irrelevant to flight, is of great importance when getting into the air in the first place. At takeoff, though indicated airspeed determines when a plane can fly, ground speed determines when it will run out of runway.

Roughly fixed indicated air speed to take off (why it's important). But at ground level, ground speed also important (to how soon you run out of runway). What ground speed is necessary to achieve indicated air speed depends on altitude and temperature (higher and hotter requires higher ground speed to achieve same indicated air speed and this achieve takeoff). Later, winds of course also affects ground speed necessary to achieve indicated air speed. Why you take off into the wind

That’s one reason long-haul flights from the Middle East traditionally depart late at night, when the air is cooler.

Airliners—since the retirement of the Concorde—fly below Mach 1, the speed of sound. But at high subsonic speeds the air over the top of the wings can reach or exceed Mach 1. This can result in the formation of shock waves that destabilize the pressure distribution around the aircraft, before the aircraft itself has exceeded the speed of sound. In order to stay within the aerodynamic design limitations that this imposes, airliners are typically engineered to cruise between Mach .78 and Mach .86.

Pay attention to Mach even on subsonic jets (all commercial now obviously) because air over wing traveling faster than aircraft and if that air moving over wing does that, can cause shockwaves and destabilize. So they're usually below Mach .85

number automatically appears in the same place on our screen where, when we were lower and slower, our ground speed was displayed. As we slow in the descent we switch again, from Mach back to airspeed.

Pay attention to different speeds at different phases of flight. Airspeed at takeoff/landing (probably eye on ground speed too), but Mach at cruising. Atc often tells them Mach speeds at cruising, sometimes translating to airspeed as they start transition to landing.

Contrails are a contraction of condensation trails;

(for their formative thoughts not only on the “Night” chapter, the first one I wrote,

Kind of makes sense. He spends a lot of time on night! Clearly passion. (I love looking out at night too, notice a lot of the same things -- though can't see pilots winking their landing lights at one another! ;) )

In writing the “Place” chapter,

Review should include "place lag"