The Well Column
Tara Parker-Pope on living well.
To recline or not to recline? That is the question now being hotly debated among air travelers after three flights were forced to land after passengers on board began fighting about reclining seats.
But are passengers really the problem? The real issue may be that most airline seats are not designed to fully accommodate the human body in its various shapes and sizes.
"We are fighting each other, but the seats are not designed right," said Kathleen M. Robinette, professor and head of the department of design, housing and merchandising at Oklahoma State University. "The seats don't fit us."
Dr. Robinette would know. She is the lead author of a landmark anthropometric survey conducted by the Air Force with a consortium of 35 organizations and published in 2002. It is widely used by seat makers and other designers.
The survey, called the Civilian American and European Surface Anthropometry Resource project, measured the bodies of 4,431 people in North America, the Netherlands and Italy. The survey collected a voluminous amount of data about its subjects, ranging from height and weight to shoe and bra size. Dr. Robinette and her colleagues made 3D scans of their subjects, allowing for detailed measurements in sitting and standing positions.
For seat designers, the most relevant data came from measurements of people sitting, which included distances from the buttock to the knee, the breadth of the hips and the height of the knees.
The data gave an accurate view of the variations in the human form, Dr. Robinette said, but the measurements have not been used correctly.
Seat designers often make the assumption that nearly everyone will be accommodated if they design a seat for a man in the 95th percentile of measurements, meaning that they are larger than all but 5 percent of other men — and, theoretically, all women. But even in that group, there are big differences.
Take the buttock-to-knee measurement of the largest men in the study: In the North American group, the average measurement was 26.5 inches, but the Dutch men were larger, measuring 27.6 inches. Factor in the fact that nobody on an airplane sits upright with the knees bent at a 90 degree angle, plus variations in calf length and thigh length.
The result is that the measurements don't really account for different body shapes and variations in the way people sit.In addition, choosing the 95th percentile of men as a cutoff means at least 5 percent, as many as 1 in 20 men, on the plane will be using seats that are too small for them. "That's about 10 people on every plane who are dis-accommodated, as well as all the people sitting next to them," Dr. Robinette said.
A big flaw in seat design, however, is that men in the 95th percentile are not necessarily larger than women, particularly in the parts of the body that are resting on the seat.
In terms of hip width, women are bigger than men. In the study, North American women in the 95th percentile had hip breadth measurements of 19.72 inches, compared to 17.15 inches for North American men.
According to SeatGuru.com, which collects data on seat sizes from dozens of airlines, the typical economy class airline seat ranges from 17 to 18 inches across. This means that seats will be snug on many bodies; for about 1 in 4 women, the seat will be too small at the hips, causing them to spill over into the adjacent seat.
Further, the widest part of the body is actually the shoulders, which is why so many of us end up knocking elbows and shoulders with the passengers next to us, or leaning into the window or aisle to avoid pressing against our seat neighbor.
The issue goes beyond passenger comfort. Dr. Robinette notes that travelers who are squeezed together and touching continually are more likely to spread cold viruses or other illnesses to a fellow passenger. People who are confined to tight seats and who can't move comfortably are at risk for painful "hot spots" — precursors to the bed sores that occur in nursing home patients who aren't moved frequently.
Of greater concern is the risk of blood clots, including a potentially deadly condition called deep vein thrombosis.
"When sitting in a way so you can't move, you start to get spots that are compression spots after maybe a half-hour or so," Dr. Robinette said. "Pain and discomfort is your body telling you something is wrong, and on an airplane there is a risk of blood clots. It's a serious problem that we are all discounting."
When it comes to reclining a seat, the most important measure of comfort is seat pitch, which is the distance from any point on one seat to the exact same point on the seat in front or behind it.
According to SeatGuru, seat pitch is a good approximation of how much seat and leg room a passenger can expect. The measurement on short-haul flights averages about 31 inches on most flights, ranging from a tight 28 inches on some airlines to a roomy 38 to 39 inches on a few.
"Seat pitch is what most fliers are concerned about," said Jami Counter, senior director of SeatGuru and TripAdvisor. "When you are talking about 31 inches as the standard, that's pretty tight; 28 inches is incredibly tight. Airlines are feeling really crowded and really cramped."
Officials at Recaro Aircraft Seating, a German seat manufacturer, said that seat design had to take into account safety requirements, weight, passenger comfort and airplane space needs, and have enough flexibility that seats can be used in various aircraft layouts.
Recaro has introduced a new seat with a slimmer back rest, giving the passenger behind the seat more space for knees and shins. The designers also moved the seat pocket above the tray table to allow for more knee room.
Recaro has received orders for more than 200,000 of the seats since introducing the model in late 2010.
"Of course, it is possible to install seats in an aircraft at a more comfortable distance from each other, so that everybody has sufficient knee and leg space," Rene Dankwerth, the vice president of research and development at Recaro, said in a written response. "However, the ticket price would definitely rise."
At 6 feet 6 inches, Chicago economics professor Devin Pope knows the risk of sitting behind someone who chooses to recline the seat. Dr. Pope likened it to a classic economics experiment called the Dictator game, in which a person is given $10 and allowed to keep it all, or share it with another person. Surprisingly, the dictator often chooses to share the money.
"It suggests that people really do care about other people sometimes," said Dr. Pope, associate professor of behavioral science at the University of Chicago's Booth School of Business. "I think it suggests why a lot of people don't lean the seat back."
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