Cockpit Confidential by Patrick Smith

designated “turbulence penetration speed” to ensure high-speed buffet protection (don’t ask) and prevent damage to the airframe. This speed is close to normal cruising speed, however, so you probably won’t notice the deceleration from your seat. We can also request higher or lower altitudes or ask for a revised routing. You’re liable to imagine the pilots in a sweaty lather: the captain barking orders, hands tight on the wheel as the ship lists from one side to another. Nothing could be further from the truth. The crew is not wrestling with the beast so much as merely riding things out. Indeed, one of the worst things a pilot could do during strong turbulence is try to fight it. Some autopilots have a special mode for these situations. Rather than increasing the number of corrective inputs, it does the opposite, desensitizing the system.
    Up front, you can imagine a conversation going like this:
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    Pilot 1: “Well, why don’t we slow it down?” [ dials a reduced Mach value into the speed control selector ]
    Pilot 2: “Ah, man, this is spilling my orange juice all down inside this cup holder.”
    Pilot 1: “Let’s see if we can get any new reports from those guys up ahead.” [ reaches for the microphone and double-checks the frequency ]
    Pilot 2: “Do you have any napkins over there?”
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    There will also be an announcement made to the passengers and a call to the cabin crew to make sure they are belted in. Pilots often request that flight attendants remain in their seats if things look menacing up ahead.
    Predicting the where, when, and how much of turbulence is more of an art than a science. We take our cues from weather charts, radar returns, and, most useful of all, real-time reports from other aircraft. Some meteorological indicators are more reliable than others. For example, those burbling, cotton-ball cumulus clouds—particularly the anvil-topped variety that occur in conjunction with thunderstorms—are always a lumpy encounter. Flights over mountain ranges and through certain frontal boundaries will also get the cabin bells dinging, as will transiting a jet stream boundary. But every now and then it’s totally unforeseen. When we hit those bumps on the way to Europe that night, what info we had told us not to expect anything worse than mild chop. Later, in an area where stronger turbulence had been forecast, it was perfectly smooth. You just don’t know.
    When we pass on reports to other crews, turbulence is graded from “light” to “extreme.” The worst encounters entail a postflight inspection by maintenance staff. There are definitions for each degree, but in practice the grades are awarded subjectively.
    I’ve never been through an extreme, but I’ve had my share of moderates and a sprinkling of severes.
    One of those severes took place in July 1992, when I was captain on a fifteen-passenger turboprop. It was, of all flights, a twentyfive-minute run from Boston to Portland, Maine. It had been a hot day, and by early evening, a forest of tightly packed cumulus towers stretched across eastern New England. The formations were short—about 8,000 feet at the tops, and deceptively pretty to look at. As the sun fell, it became one of the most picturesque skyscapes I’ve ever seen, with buildups in every direction forming a horizon-wide garden of pink coral columns. They were beautiful and, it turned out, quite violent—little volcanoes spewing out invisible updrafts. The pummeling came on with a vengeance until it felt like being stuck in an upside-down avalanche. Even with my shoulder harness pulled snug, I remember holding up a hand to brace myself, afraid my head might hit the ceiling. Minutes later, we landed safely in Portland. No damage, no injuries.
    So that I’m not accused of sugarcoating, I concede that powerful turbulence has, on occasion, resulted in damage to aircraft and injury to