I’ve never experienced horizontal turbulence. Twenty minutes before its scheduled landing at Washington Reagan airport, our plane is sliding from side to side like a teacup on a Ouija board spelling out the words You’re going to die. As instructed by the crew, I fold and stow my seatback table — an FAA-mandated precaution, its potential lifesaving value in the event of an actual crash I’ve yet to grasp — and buckle my seatbelt, which makes its fateful click. Then, so as to not alarm my fellow passengers who are surely concerned about not alarming me, I pray while pretending not to pray, silently, eyes open and head up. I’ve often heard experts say that turbulence, even at its most extreme, isn’t enough to bring down a modern jet, but I’ve also heard experts say that rattlesnake bites are far less dangerous than people think — experts who don’t know my friend who almost died from one, his decline so rapid and agonizing that the doctors made him phone his daughter and say goodbye to her …