Friday, September 12, 2014

Taking a position on plane comfort



To recline or not to recline? That is the question being hotly debated among air travellers after three flights were forced to land following fights among passengers over reclining seats.

However, 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 Dr Kathleen 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 United States Air Force with a consortium of 35 organisations and published in 2002. It has been 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 as well as Italy.

It also 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 information came from measurements of people sitting, which included distances from the buttock to the knees, the breadth of the hips and height of the knees.

The data gave an accurate view of the variations in the human form, said Dr Robinette, 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 they are larger than all but 5 per cent of other men — and, theoretically, all women.

However, 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 a plane sits upright with the knees bent at a 90-degree angle, plus variations in calf and thigh lengths.

The result is that the measurements do not really account for different body shapes and variations in the way people sit.

In addition, choosing the 95th percentile of men as a cut-off means at least 5 per cent, or as many as one 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,” said Dr Robinette.

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, wider than the 17.15 inches for North American men., which collects information on seat sizes from dozens of airlines, said the typical economy-class airline seat ranges from 17 to 18 inches across.

This means seats will be snug on many bodies — for about one in four women, the seat will be too small at the hips, causing them to spill over into the adjacent seat.

In addition, the widest part of the body is actually the shoulders, which is why so many of us end up knocking elbows and shoulders with passengers next to us or leaning into the window or aisle to avoid pressing against our neighbour.


The issue goes beyond passenger comfort. Dr Robinette notes that travellers 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 cannot move comfortably are at risk of painful “hot spots” — precursors to bed sores that occur in nursing-home patients who are not 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 half an hour or so,” said Dr Robinette.

“Pain and discomfort is your body telling you something is wrong and, on a plane, 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 a seat to the exact same point on the one 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 others.

“Seat pitch is what most fliers are concerned about,” said Mr 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.”



Tara Parker-Pope is an author of books on health topics and a columnist for the New York Times, where she writes the Well blog

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