It’s not every day that a flight is delayed because there are too few people on board. But, blame Will and Kate, Brits just weren’t flying out of London last Friday. As a result, the Virgin Atlantic A340-600 called Ladybird was carrying only 112 of her usual 380 passengers.
So before we could take off, we had to play a little game of musical chairs. This was done to balance out the plane. Rows 37-40 were blocked off so no one could sit in them. A lady from a middle section was asked to move next to me over on the right side of the plane, and similar reconfigurations took place all over economy. (A flight attendant confirmed my suspicion that no Upper Class passengers were made to move from their pods.) Everyone was free to prowl around the cabin and claim the empty rows once we reached cruising altitude, but the seat distribution had to be exact for takeoff and landing.
The culprit? Turbulence. At cruising altitude, it’s no big deal: Planes can withstand rollercoaster altitude drops that leave their passengers banged up and surfing a sea of vomit. But at takeoff and landing, an unbalanced plane makes things dicey. It’s easier to navigate an empty or even an overweight plane through liftoff turbulence than to do the same for a sparsely populated plane.
To balance the plane, the crew tries to distribute the weight of the passengers, so that the plane’s center of gravity is proper. Recently this practice led to a dustup when an overweight passenger was asked to move to the back of the plane to balance the load.
So why is takeoff and landing so touchy? Turns out that turbulence and wind shear—which is when the speed of two contiguous air streams are different enough to cause chaotic air movements—are a lot more dangerous at altitudes below 1000 feet. Here, turbulence can cause a pilot to lose control, because he has less lift, the plane is flying more slowly, and there’s much less room to recover from a problem. According to Boeing’s Statistical Summary of Commercial Jet Airplane Accidents, 1959 – 2008, about 80 percent of all accidents involving aircraft occur during take-off and landing.
Most aviation experts I’ve been reading agree that turbulence at cruising altitude is no big deal. “It would take an incredible amount of force to turn [a plane] over or put it out of control,” Larry Cornman of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., told Science News in 1998. (By the way, you should read this article if you’re afraid of flying—after 13 years, it’s still fantastic.)
There are three different kinds of turbulence: storm turbulence, mountain turbulence and clear turbulence. The first two are relatively self-explanatory; the third is trickier:
One of the main culprits of clear-air turbulence is the boundary between the jet stream—that aerial river that forms where arctic air masses meet warmer air from the south—and the slower-moving air adjacent to it. This invisible boundary shifts unpredictably, and woe to any unstrapped passenger in a jet that crosses it.
It generally happens above 18,000 feet, and as the name suggests, without visual hints like clouds, it’s pretty hard to take evasive maneuvers.
“It’s like hitting a speed bump at 500 mph,” aviation consultant John Nance told ABC News in 2009 after a particularly nasty bit of unexpected turbulence caused some serious injuries on Continental flight 128. “It’s very, very violent.”
Technologies like scintillometers or Doppler LIDARs have gotten better at giving some early warning.
However, it’s possible that we could be in for more turbulence despite better technologies. One of the most interesting theories I’ve read is that that climate change will make turbulence worse.
According to the Federal Aviation Administration (FAA), air turbulence is the leading cause of airplane injuries. And stronger storms triggered by global warming may make turbulence worse: The International Panel on Climate Change has suggested that global warming causes water temperatures to warm, and the rising heat from those waters can lead to more disturbances in the upper atmosphere. It’s those upper-air disturbances that cause in-flight turbulence.
I wonder if that’s true. I’ve been looking for data to see whether incidents of severe cruising altitude turbulence have increased, but you can imagine the trouble with that question. Too many variables: The number of airplanes has increased since 1995. We’ve gotten better at mitigating some kinds of turbulence. If anyone has anything to say about the matter, I’d be very curious to hear your comments.
But at the end of the day, nothing can take away my love of flying. In 200,000 years of humanoid presence on this planet, only we privileged few born in the past 50-ish years can enjoy a view of the cloud tops. I’ve flown beneath Leonids, through boiling columns of thunderstorm clouds, and over the unforgettable neon orange of a Manhattan sunset. My flight attendant on the Ladybird tells me he saw the Northern Lights over Russia. He also said he once watched as a lightning bolt zipped safely through the plane (which he tells me is safe because the craft was not grounded. Not sure I believe that but he’s still around so I’ll take his word for it).
To me, that makes the risk of death kind of worth it. Your mileage may vary.
Thanks for linking to the Science News article. I am absolutely terrified of flying. Takeoff, turbulence, landing–all of it. No amount of knowledge will make me less scared, but it’s still good to know. I also had a similar experience of flying on a nearly empty flight, from London to DC. But British Airways must be less concerned about unbalanced planes; we were never asked to rearrange ourselves, and my neurotic self did wonder if an empty plane was more likely to crash than a full one….
Lighting is perfectly fine striking a plane — it happens all the time. Scientific American says each plane in a fleet will get struck once a year: http://www.scientificamerican.com/article.cfm?id=what-happens-when-lightni
Lightning will strike the outer shell in pointed areas (tips of wings, tail, etc.) where charge can be best concentrated. The exteriors of commercial airplanes are made to conduct electricity very well — aluminum, I think? — which keeps any charge on the outside, safely away from passengers.
Personal planes (such as ultralights) are definitely less protected — fuel is more exposed, so is the cabin, and there is less protection over all.
Interestingly, airplanes are made to embrace electricity, because there’s no way to fight it.
Nice article. I also love flying, and watching landscapes pass by 20,000 feet below. Also I’ve been on a plane struck by lightning. It makes quite a big bang, followed by the vague sounds of muted terror from dozens of unnecessarily terrified passengers. I guess I sort of perversely enjoyed that.
I might just point out though, that ‘ladybird’ in the picture is a boeing 747, not an A340