Cold, Hot And More

Temperature extremes are proven to reduce our effectiveness with complex tasks. Understand how it happens and by how much.


Have you ever been so cold your fingers got numb? Ever freeze your feet numb? This is the beginning of frostbite, in case you didn’t know. Which I totally didn’t, the first time my feet went numb while ice skating outdoors in Minnesota. It was -30 degrees F and I was playing hockey with the neighbor kids. I didn’t know my feet were numb—until I walked home on my skates, and got inside. 

As my feet thawed out, I was in agony—they didn’t hurt until they warmed up. I vowed never to do that again. And I didn’t, way up until the fifth grade, again in the seventh grade and one more time when I was about 28 years old. (Because of all that frostbite, nowadays my feet get cold when I walk on a white floor.) Every single time I froze them, I remember thinking, “I’ll never do this again!”

Why all the talk about getting cold? Where’s the flying story, Mr. Pilot Person? All right, all right. “So, there I was….”


The temperature is -54 degrees F, and we’re taxiing out in a U.S. Air Force KC-135Q, a Boeing 707 fitted with extra tanks for aerial refueling. Near Fairbanks, Alaska, in mid-January. At night, which is pretty much any hour of the “day” there in the winter. 

No “wind chill” factor—straight-up -54, in your face. No wind at all—dead calm. The snow piled itself straight up on top of the telephone wires. Tires froze on vehicles, and there would be flat spots. If you walked fast, which you doggone are gonna do, the slight breeze gives your face a little frost nip, and you look tanned. 

Physical factors affect the mind—big time. And the mind affects your decision-making, and then of course stick-and-rudder skills. How about if you are so darned cold you can’t really think straight, and fly into a mountain? 

A crew of four were flying out of that same base, Eielson Air Base, Alaska, in the winter, same aircraft. They had been sitting, waiting in the frigid temperature in the cockpit for quite a while. No heat. They were “cold-soaked.” Then they finally took off, and the gear wouldn’t come up, and they fixated on that problem, and flew, eventually, into a mountain about 15-20 miles away. Straight ahead.

Oh, the Monday-morning quarterbacks, the smarmy know-it-alls, might say—as I heard one tanker pilot say—“Why didn’t they just aim at lower terrain? The airfield behind them is lower terrain.” Because they were all frozen and tired is why. 

I mentioned this episode in an article a few months ago, but it’s worth repeating: My feet got frozen solid, sitting in a KC-135 in the -54 degree F temperature at Eielson. There’s no heat on a tanker from the time they pull out the heater hose until you’re airborne. Who knew?

We had some small leak, some problem, and had to stop and shut down on the taxiway while maintenance looked at it. By the time the guys came out with a huge hot-air hose and ran it up into the cockpit through the bottom door, I was in agony. My feet were numb, and had been for minutes. And when your frozen-numb appendages thaw, why, the pain is really quite exhilarating, in a negative way.

I was almost crying—but I was an Air Force officer and couldn’t look bad in front of the other crew members. So I just wept inwardly and cursed outwardly, all the better to look “tough,” with my stocking feet inside the huge heater hose blowing blessed heat. We eventually took off that night and, of course, our gear wouldn’t come up, just like that accident aircraft, many years before.

All I thought about when we worked on getting the gear up was, “We are not flying into that mountain. We are not flying into that mountain.” The gear came up, eventually—one last lucky tug upward on the big handle by the aircraft commander—et voilà!—and no more three green lights.

Human Performance And Temperature Extremes

It’s not difficult to understand that temperature extremes can affect human performance. If it’s not chattering teeth and stiff digits, it’s sweat pouring off our brow and the need to hydrate. Hydration, of course, has its own side effects. But what’s an extreme temperature? How long does it take to be affected? And how will an extreme temperature affect my ability to fly an airplane?

A “meta-analytic review” conducted in 2002 by June J. Pilcher, Eric Nadler and Caroline Busch, appeared in Ergonomics, Volume 45, Issue 10, and the researchers were able to quantify some of what we at least think we already knew. According to the study, “cold exposure resulted in worse performance (10.06% decrement) than hot exposure (5.96% decrement).” In other words, extreme cold is likely to have a greater impact on pilot performance than extreme heat, but both result in loss of effectiveness. To no one’s great surprise, the nearer we are to the neutral range (65-75 deg. F for extreme cold and 60-70 deg. F for hot), “the less effect it had on performance.”

What we might call chilly temps resulted in a 7.81-percent decrement in performance and really cold ones meant a 13.91-percent decrement. On the other end of the thermometer, a merely warm environment resulted in a 0.80-percent loss of performance, hot ones came in with a 7.50-percent decrement and very hot ones rang the bell at 14.88 percent.

I don’t know about you, but I need all the cockpit effectiveness I can find. I’d rather not give up 15 percent or more of it, but at least I now know what the effects can be. — J.B.


Have you ever been flying, and had to go to the bathroom really, really bad? I mean, so bad you’re almost panicking? So bad that you actually wet your pants a little? Or a lot?

No? Oh, really? Okay, then—me either.

But I imagine that it would affect my judgment, my aeronautical decision-making. Thinking aloud here—just spitballing—I think I would find the nearest airport and make a very hurried approach and landing. I might even just shut down on a taxiway, jump out and, uh, “go” right there on the grass (or not the grass), thankful to just have lowered the gear and not crashed. The pain, discomfort and distraction from a full bladder is that bad.

Oh yes, the “my bladder is the size of a basketball-syndrome” is as real as can be, when flying single-pilot. Now I carry a large metal jug with me when I fly. Strategically, this jug is a different color than the one I drink from. Tip: A larger jug is better, since once you start it’s hard to stop. Wrapping a coat or shirt around your waist before entering the FBO will hide what the FAA calls “evidence”—evidence of carrying a too-small jug. And, oh yeah: You do know the FAA has an entire “Operation Golden Flow” division devoted to—okay, no, they don’t have anything like that.

Hunger—being hungry—is the one bodily-function-thing that seems to make me sharper, fly better and be more alert. On the other hand, if I eat a bunch of food, I get sleepy and sluggish. Like a python after swallowing an entire goat, my brain slows down, and I start to become mere self-loading cargo instead of a PIC. Especially if the autopilot is on, which it always is.

Winter Flight Planning

Planning for any flight in extreme weather starts a couple of days ahead of the proposed departure time. You’ll want to nail down the trends and the forecasts: Is it as bad (or good) as forecast? Did the weather-guessers get this one right, or nearly so? Watch the trends, pay attention to the prog charts, especially for forecast front positions and what they may portend for lake-effect weather. The data you’ll find is rather coarse two or more days out, but it starts to firm up as you get within 24 hours of your ETD.

By that time, you’ve already made arrangements to put the airplane in a heated hangar the night before—right?—n addition to ensuring all the ice or snow that may have accumulated has melted by the time to depart and, hopefully, evaporated also. If you’re living right, you might even be able to do your walk-around in shirtsleeve comfort before rolling your flivver out to the ramp, loading it up and blasting off.

All the time and energy you could have used to deice and thaw out the airplane now can be spent understanding the winter weather you’re about to face. Some tips beyond intimate familiarity with the prog charts might include:

• Where’s the freezing level? Can you stay below it? If an icing Airmet or Sigmet exists, can you go around it and/or maintain vertical separation?

• Is your destination even open? Just because you can get out fine, that doesn’t mean your destination isn’t snowed in, or has seen a snowplow. Especially at smaller airports, call ahead. At larger ones, call ahead anyway and verify things like ramp or hangar space, deicing fluid and/or Prist availability, etc.

• How much runway do you need? On dry, level pavement runway performance is easy to calculate. Not so on snowy, slick surfaces. Check braking action reports before you go, but run the worst-case numbers to verify you can get down and stopped, or need to go somewhere else.

• Pick a solid-gold alternate. Ideally, it has nearby hotels and rental cars, but it also has to be open and within range.

• Stop for fuel en route. It’s a really bad idea to stretch fuel in winter. Stop and take a break, top the tanks and empty the bladder. Then you’ll be ready almost anything. — J.B.


How about heat? Not that it’s hot up here in North Dakota right now. Can heat make you go mental and do dumb stuff while flying? Absolutely.

I was stationed at an Air Force base on the Texas-Mexico border, and it was hot there in the summer, summer lasting approximately 14 months of the year.

The Australians—crikey!—have what they call an “EHP,” or extreme heat policy at the Australian Open tennis tournament. This is held in January, their summer. Their EHP is a complicated rule which takes into account four climate factors: radiant heat, air temperature in the shade, relative humidity and wind speed. Tennis players have keeled over from the heat, and had to have transfusions in the past. Fans wilt.

The U.S. Air Force—in 1991, anyway—had a simple EHP: they only measured the air temperature, which was written on a white board near the door to the ramp with warnings such as, “ONLY FIFTEEN (15) MINUTES ALLOWED OUTSIDE OF AIR CONDITIONING BEFORE COMING BACK INSIDE FOR THIRTY (30) MINUTES.”

So we Air Force pukes had to hurry up with the walk-around (the “run around’) and if there was any delay, we’d have to cancel the mission and come back inside, all sweaty. I’m sure there was a “fudge factor” built into that 15 minutes, but I suppose there had to be a cut-off somewhere—but the rule was 15 minutes outside, when it got really hot. Hot like 44 degrees C.

When you first walk out into the blistering heat on the ramp, where the sun is reflected up, and the air temperature can be way above 120 degrees, it doesn’t seem dangerously hot. But after about 10 minutes, a person is hurrying—not just to be “legal,” but to get that darned air conditioning on.

The U.S. Air Force, which had a long history of flying—along with a lot of accidents—was interested in preventing them, not scolding or prosecuting people. Well, they were interested in that, too, but not as much. They had all kinds of good, common-sense rules.


But in general aviation, we’re kinda on our own. Like the Air Force, unfortunately, we also have a long history of flying—along with a lot of accidents. Of course, we have no parental supervision. We can put in fuel or not, check the oil or not, and wear shorts in January in Fargo, when the wind chill may hit 80 below zero.

Once when in my 20s, I flew with a buddy of mine aboard a Cessna 172 from Marysville, California, to Lake Tahoe. He was building hours at that time—now he’s been a captain at Southwest for some 20 years. But at that time, I was already flying KC-135 and T-38 jets in the Air Force, and felt quite superior in every way to him, with his 213 hours of bug-smasher time. 

But I almost killed us with my dumb-assedness, which was exacerbated (there, I finally used that word!) by the cold.


In the early winter morning at Lake Tahoe, he did the preflight. He had no hat or gloves in the bitter cold. My “amateur pilot” friend insisted on scraping off all the frost from the aircraft—every speck. He used a credit card with one hand, the other over one ear, and then the other. 

Even though I had a hat and gloves on, I was cold (because I had no long undies). I said, “Come on, come on, just leave it!” But he kept scraping. And scraping. I thought “Just scrape a hole so we can see and let’s take off!” He finally got all the stupid frost off the airplane.

It was only years later, when I became a CFI flying light airplanes, that I realized he had probably saved our lives with his credit-card scraping. 

A high-density-altitude airport, aircraft covered with frost, little airplane full of fuel and two guys? We might have augered in if we got airborne, or not gotten airborne at all and “parked” in the lake. The cold affected my thinking. That and I knew nothing about Cessna 172 wings needing “clean metal” to fly worth a darn.

So no joke: The effect of cold temps or hot temps—or having to go to the bathroom really, really bad—can severely affect a pilot’s judgment. And nobody really talks about it all that much.


Matt Johnson is former U.S. Air Force T-38 instructor pilot and KC-135Q copilot. He’s now a Minnesota-based flight instructor.


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