Airline seats have been one-size-fits-all since the beginning. Today, those 16.5 to 18-inch wide seats are anything but.

According to the World Health Organization (WHO), obesity has more than doubled since 1980. In 2014, more than 1.9 billion adults were overweight, and over 600 million were obese. (WHO defines "overweight" as a BMI greater than or equal to 25 and "obese" as a BMI greater than or equal to 30.)

It’s a trend that has thrown up thorny issues with respect to air travel, one that highlights the conflict between airlines’ needs and basic passenger rights.

Last month, lawyer Giorgio Destro from Padua, Italy sued Emirates, claiming his flight was disrupted by an obese passenger seated next to him. According to reports, Destro was not able to comfortably sit in his assigned seat, and spent much of the nine-hour flight from Cape Town to Dubai standing or sitting in crew seats. His proof for the lawsuit? A selfie that includes his fellow passenger’s arm in his seat space.

Obesity has more than doubled since 1980.

Passenger rights advocates argue that most aeroplanes can’t accommodate passengers of all body types, and that everyone has the right to fly.

“Tall, short, thin or fat, broad shoulders, wide hips or longer legs… people come in all sizes and it is rare for any coach seat to provide a comfortable and pleasant travel experience,” says Peggy Howell, Vice Chairman and Public Relations Director of National Association to Advance Fat Acceptance (NAAFA). “The responsibility of serving customers of all sizes is the cost of doing business in today’s modern world and that cost should not come at the expense of any one group of individuals.”

Mass charges

Many airlines have responded to the growing obesity epidemic by insisting passengers of size buy two seats to ensure safety and comfort. Sometimes the airline will offer a refund if there was at least one other empty seat on the flight.

But as of late a new fee has been created. Samoa Air is charging by weight (which has become known as a "fat tax"). On top of all the other additional charges that appear to be creeping in, from checked baggage fees to in-flight drinks, is charging heavy customers an extra fee another profit ploy? And should added charges really extend to how much a person weighs?

The responsibility of serving customers of all sizes is the cost of doing business in today’s modern world.

At first glance, the fat tax issue sounds discriminatory, but some argue that this is purely down to numbers. The heavier a plane is, the more fuel it burns through. And airlines are always looking for ways to travel lighter.

One clue to the effect of in-flight loads comes from pilots. For 75 years, pilots have had to haul 40-pound Jeppesen flight manuals aboard every working flight, but now most US airlines have spent millions of dollars converting these heavy bags to electronic flight bags — in other words, iPads. “Between two pilots, that’s 80 pounds per takeoff,” says Kurt Doerflein, a veteran mechanic for a major US carrier. “At over 100,000 commercial flights a day in the world, that adds up.” For instance, American Airlines has said the switch would save the airline $1.2 million a year in fuel costs.

As well as charging customers by weight, which Samoa Air insists is not intended to create shame, it also offers an XL (extra large) row that has a more comfortable seat for larger people. It measures 12 to 14 inches wider than the traditional seat.

Chris Langton, Chief Executive Officer of Samoa Air says the pay-by-weight system isn’t going anywhere. “Aircraft only have weight to sell and people will recognise that immediately,” he says . “So they will ask questions as to why should light-weight people pay for heavy-weight people, and why they get charged for ‘excess weight’ with excessive fees.”

The heavier a plane is, the more fuel it burns through.

In other words, the argument is whether it is fair that a 150-pound person is charged for their 50-pound bag, when a 300-pound person with a carry-on isn’t charged anything extra. “As we say, ‘a kilo is a kilo is a kilo,’” Langton says. “So it has nothing to do with the condition of the weight.”

However, Peggy Howell of NAAFA argues that obesity is an illness, and that obese people should be entitled to having certain rights protected.

“We question the legality of the discriminatory policy and whether it violates the Air Carrier Access Act governing the treatment of passengers with disabilities,” she says. “The American Medical Association (AMA) recently declared obesity a disease, which should make fat passengers a protected class.”

Howell points out that the Canadian Transportation Agency (CTA) addressed this issue in 2009, and issued a ‘one-person, one-fare’ ruling covering passengers with disabilities. Those passengers include ones who are ‘clinically obese’ and who cannot fit into a single seat. (Clinically obese is defined as having a BMI of 35 or higher.)

Cost of weight

What isn’t fully clear yet is how much passenger weight actually drives up costs compared to other factors like fuel, labour, aircraft ownership and maintenance.

“On the surface level, a heavier passenger does increase the overall weight onboard an aircraft — therefore increasing fuel burn and cost to the airline,” says Luke Jensen, a researcher at MIT International Center for Air Transportation. “The actual difference in fuel cost varies by flight, but rough order of magnitude, the difference is relatively small. On a typical 737 flight from Boston to Denver for example, a 50-pound weight increase would increase fuel consumption by about $3 to $5.”

Is it fair that a 150-pound person is charged for their 50-pound bag, when a 300-pound person with a carry-on isn’t charged anything extra?

He says that it might be “fair” to weigh each passenger and his or her bag, and then charge them accordingly — he says it could be less than a $10 difference between smaller and larger passengers on most domestic flights.

“Given that body weight is driven by both genetic and behavioural factors, the purely economic argument loses heft,” says Jensen. “The airline is selling a common-carriage seat, not a payload allocation — and common carriage implies that tickets are made available without respect to race or gender.”

He does point to one key exception: that in some cases, the aircraft’s weight distribution affects safety of the flight, especially on smaller aircrafts.

“Large jets are also subject to limitations in weight and loading, but normally have larger engineering margins,” says Jensen. “In cases where the airline deems that weighing passengers is necessary for safe operations, I think it is certainly justified.”

Seating plans

Ultimately, the solution will be to start at the very beginning: with the design of the aircraft cabin itself. “There is a long way to go,” admits Langton. “Boeing and Airbus and other aircraft manufacturers will need to redesign the inside of an aircraft in order to accommodate in both pitch and width so that people get what they must pay for: weight.”

But some ideas are on the drawing board. In 2015, German IT and engineering company SII Deutschland’s SANTO Seat won the Crystal Cabin Award in the category “Passenger Comfort Hardware”. The seat size is one-and-a-half times the width of the average airline seat, and its objective is to safely accommodate passengers travelling with toddlers and overweight passengers in the rear of the aircraft cabin where the fuselage narrows.

Another possible option is a "reconfigurable passenger bench seat" by Airbus' Sven Taubert and Florian Schmidt. The bench would be flex space that can accommodate larger people of several peoples, such a family with young children. The patent is pending.

For now, there may be a surprisingly simple solution. There are spots that people can seek out on existing planes to try and secure the most space.

“With respect to seat width, something that most people don’t realise is the seat width is different based on the location in the cabin,” says Doerflein. “For example, the first five rows and the last five rows are much narrower.” His tip: “The roomiest seats are in the middle of the aircraft.”

Beth Blair is a former flight attendant and a freelance writer.

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