The Last Word on Downwind Turns, Really | Flying Magazine

The Last Word on Downwind Turns, Really

Debunking one of aviation's most pervasive myths.

Downwind Turns Art

Downwind Turns Art

** Illustration: Ken Dubrowski**

The following article is from the January 2005 print issue.

"Nope," I said. "No way. There's no way that a turn downwind, or upwind, or in any other direction, is any different from a turn in still air."

"Well, sonny," said the Old-Timer, "maybe out your way the air's made of different stuff. But I've buried enough pilots to know that in these parts, when that wind comes around an' hits ya from behind, if ya don' have enough of a cushion, you're just gonna stall. There's no two ways about it. lt's just common sense. That wind's gonna hit ya from behind, and that's all she wrote. Y'all writers, y'all're so used to smoke and mirrors, y'all can't see what's right in front of ya."

As he finished saying these words, an odd smirk played upon his lips.

I thought best not to insist. Thanking my companion for the favor of his company, I tossed my bag into the back seat of my car and drove off.

My first inkling of something strange came on the highway. I was doing about 70 or so, and I noticed that whenever I turned my head ever so little, I got a ditty feeling. I chalked it up to having skipped lunch. But I had to change lanes to turn into the parking lot of the Alamo Inn, and when I turned my head to look for traffic behind me, I got a painful jolt. Later, as I meditatively nursed my whiplash, I realized what must have caused it. My head had been moving forward at maybe 30 miles an hour. When I turned to look behind me, my head was suddenly going backwards at 30 miles an hour. The 60-mph change in velocity had taken place in less than a second. Small wonder I had hurt myself.

The following day the weather was terrible, and I decided that rather than fly to my next stop, which was less than 100 miles away, l'd take the train and return in the evening. My trip was uneventful, and actually quite pleasant; it was nice to be able to read and leave the driving to someone else. At least it was pleasant until I decided to visit the restroom. I got out of my seat and walked toward the back of the car. At a certain point I realized that a couple of other people were already waiting in line there, and so I turned around to try one farther forward.

I awoke to find myself supine on the floor of the railroad car, with several concerned fellow-passengers bending over me. I was breathing with difficulty, but soon recovered myself and crept to my feet. Reassuring everyone that I was all right, I regained my seat, where I resolved to stay put until the train had come to a stop in the station.

It was clear to me now what had taken place. Walking toward the back of the car, I had been moving backward at about 66 mph — assuming that the speed of the train was 70. When I turned around and took a step in the other direction, I was now moving forward at 74 mph — a change in velocity of 140 mph over the space of a couple of seconds. Naturally, the violent acceleration had hurled me backward and knocked the wind out of me. I resolved to be more aware of my surroundings in the future.

At the end of the week I was obliged to take an airline flight. By now I was all too aware of the dangers of sudden changes of direction on a moving conveyance, and was firmly resolved to spin no more. In the course of the flight I was once again obliged to heed a call of nature, and once again I started of in the wrong direction. But I was not about to repeat the mistake I had made on the train. After all, I realized that a rapid about-face now would entail a velocity change of close to 1,000 mph, which could easily reduce me to a pink film on the aft bulkhead. Having calculated in advance that if I allowed 45 seconds to turn around in the aisle I would probably be safe from injury, I reversed my direction with exquisite care and slowness, always keeping both hands on the seat backs beside me. So absorbed was I in this process, and so alert to the first hint of an unwelcome acceleration, that I scarcely noticed that some of my fellow passengers were looking at me apprehensively. I had nearly completed my 180-degree turn when I became aware of a blunt object pressed against my back and a soft voice in my ear.

"I am Air Marshal McGraw," it said. "If you'll just quietly cooperate, sir, there doesn't have to be any trouble."

I had a terrible time explaining myself, because the TSA people simply refused to grasp the simple physics of the situation, even when I carefully diagrammed the inertial reference frame for them on a sheet of graph paper, complete with arrows and subscripted V's for "velocity" — V0, V1, and so on. They seemed totally unaware of the terrible dangers attendant upon any change of direction by a pedestrian in a moving airliner. I'm surprised that accidents are not more frequent; no doubt the airlines are at pains to cover them up.

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