|Image Credit: Jason Pratt|
|See that plane on the upper left?|
Say It Isn’t So
Since anecdotal boyfriend babble is not always accepted as a reliable source, I’ve done some research on the question of whether turbulence can cause aviation disasters. The answer turns out to be a heavily-caveated yes. Turbulence can lead to plane crashes, but it is exceedingly rare. By some estimates, turbulence takes down about one plane per decade.§ This chaotic air movement - and its effects on the movement of the aircraft - is classified in degrees of light, moderate, severe and EXTREME (emphasis added by author). There’s also something called “chop” which is a more rhythmic bumpity-bumpity effect that comes in light and moderate flavors. Passenger perception of turbulence tends to be direr than that of experienced crew, so if you think you’ve been on the worst flight of your life, it’s likely you only witnessed moderate turbulence.
The good news is that airplanes are designed to withstand extreme turbulence (as well as lightning). The bad news is that, like all machines, airplanes age. Wear and tear that is no problem under normal circumstances can make aircraft less resilient to ridiculous levels of turbulence. Additionally, flying a plane that is being pummeled by rogue air masses isn’t the easiest thing in the world. Planes can be pretty much out of control during these episodes and, while temporary, the pressure is really on the pilot to react (but not overreact) in a way that keeps the aircraft from flying into the side of a mountain. If you think this all sounds melodramatic, consider a 1966 incident in which a BOAC (now British Airways) Boeing 707, flying near Mt Fuji, broke up in midair and crashed amidst harsh winds.
Your Wake, My Funeral
As frightening as that is, you should probably be more concerned about something called “wake turbulence”. Unlike turbulence created by naturally occurring differences in air flow (bad weather, pressure variations near mountains, jet streams, etc.), wake turbulence is caused by other airplanes, sort of like the wake created by a boat, except with air and much scarier. The worst part of wake turbulence is the creation of “wingtip vortices”, tornadoes of bumpy air generated by a plane’s wings that can take several minutes to dissipate.
|Image Credit: NASA Langley Research Center|
As with other forms of turbulence, wake turbulence is more of a threat to small planes (especially when caused by the significant wakes of large commercial jets). Probably the largest aircraft to crash as a result of the phenomenon was a McDonnell Douglas DC-9 that got caught in the wake of a Lockheed L-1011 in 1972, prior to the implementation of the above-mentioned spacing regulations.** Wake turbulence allegedly also contributed to the 2001 demise of American Airlines Flight 587, though this crash is officially attributed to pilot error in response to the wake.
And now let me stress how very, very rare these occurrences are. Finding examples with which to freak you out was no easy task. Really, the biggest of your worries in the realm of bumpy air is encountering clear air turbulence (CAT) when you don’t have your seatbelt fastened. This is the surprise turbulence that occurs on a sunny day in seemingly smooth skies. The major impact of turbulence is not the causing of plane crashes, but rather bodily injury from all that jerking around. Every year, dozens of un-seatbelted passengers are seriously injured (and occasionally even killed) from being thrown around the cabins of twitchy planes. Your pilot isn’t just being an overbearing nag when he (or she) asks you to keep your seatbelt fastened when you aren’t walking around the cabin. CAT can come out of nowhere and knock the #%$ out of a plane. So buckle up, people.
* By the way, I’m afraid of cars too, making such logic even more useless to me.
† I went to Spain. It was lovely, thanks for asking.
‡ Wind shear turns out to be variations in speed and direction of air movement, which often leads to turbulence. Possibly he was talking about wake turbulence rather than wind shear. Maybe he even said wake turbulence. I don’t know, I was still a bit rattled (pun not intended, but permitted) at the time.
§ This was reported in the Guardian (via the aviation consultant Ascend) and they didn’t elaborate on what types of planes – or types of turbulence for that matter –were involved in these disasters.
** The DC-9 is still relatively small compared to a wide-body behemoth like the Lockheed L-1011.