How much more room could we have on airplanes if we weren’t overweight?

Posted on November 14, 2016

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I recently read an article about how the amount of unruly incidents on planes has gone up 17% in the last year. It’s hard to imagine the increasing sensation you’ve unintentionally signed up for a gang bang -due to the proximity to other people- isn’t at least part of the reason for this increase.

Being overweight on a plane is a double whammy. The extra weight causes the airline to need to either charge more or decrease services in some manner. Whether that be less or no food, no entertainment, something.

-> If you’ve flown recently, you may have noticed a decrease in the amount of televisions on board. Some airlines have gone back to where multiple rows have to watch one TV, and some have completely removed the television in favor of allowing people to stream content on their phones. Why? To save weight!

Also why Spirit Airlines tray table, arm rest, and manual holder look like this:

(The manual is two pages, no magazines, and the holder is a thin bungee cord!)

And why they don’t accept cash on board either.

Another one of those somethings is packing the seats in tighter, to try and get more people on board => more money made per flight. We’ve gone over how much our weight influences prices, now we’ll go over how much our size influences the space we have on board.

Body Mass Index is commonly used to assess overweight or obese.

  • 25 to 29 is overweight
  • 30 and up is obese

Extreme obesity is classified at a BMI of 40 and over.

BMI = (bodyweight in kilograms) / (height in meters^2)

body mass index chart

We’ll say the median overweight person has a BMI in the middle, 27.5, and the median obese person has a BMI of 35. So we’ll say half of obese are lower than 35; half are higher.

Average U.S. adult height is 5’6″ or 1.68 meters.

Overweight people:

27.5 = bodyweight / (1.68^2)

(1.68^2) * 27.5 = 78 kilograms

The average overweight person in America has a bodyweight of 78 kilograms. 171 pounds.

Obese people:

35 = bodyweight / (1.68^2)

(1.68^2) * 35 = 99 kilograms.

The average obese person in America has a bodyweight of 99 kilograms. 217 pounds.

Let’s say we could wave a magic wand and get all these people with weight to lose down to a BMI of 22.5, right in the middle of what we consider the healthiest BMI range.

Adults:

22.5 = bodyweight / (1.68^2)

(1.68^2) * 22.5 = 64 kilograms or 141 pounds

Meaning:

Overweight people => 171 pounds – 141 pounds = 30 pounds

Obese people => 217 pounds – 141 pounds = 76 pounds

The average overweight person is unnecessarily carrying around 30 extra pounds, while the average obese person has 76. More weight on our bodies means more size. This is unnecessary size we bring with us onto a plane.

Alright, we’re going to use a Boeing 737 as our example flight, as this is the most produced aircraft for commercial purposes of all time, and still in heavy production.

The 737 has a subgroup of versions. The 600, 700, 800, 900. We’ll use the 700, as Southwest’s fleet is 67% this version. The passenger load is 143 people for a Southwest 700. Call it 147 with a four person crew.

In America, two-thirds are above a healthy BMI. One-third overweight; one-third obese.

147 * 1/3 = 49 overweight people on the flight

147 * 1/3 = 49 obese people on the flight

(and we’ll say the remaining third are normal weight)

How much volume do these people take up?

  • an overweight person has a weight of 171 pounds. Volume wise, that’s 0.08 meters^3.
    • While more nuanced, the calculator link above is extremely similar to the values in this chart:

      Note volume is in liters. Divide by 1000 to get meters^3. Credit: Determination of human body volume from height and weight

      Note volume is in liters. Divide by 1000 to get meters^3.
      Credit: Determination of human body volume from height and weight

  • an obese person at 217 pounds is 0.10 meters ^3.

For a full 737 plane,

  • 49 overweight people * 0.08 meters^3 = 3.92 meters^3
  • 49 obese people * 0.10 meters^3 = 4.9 meters^3

Compared to healthy weight,

  • 141 pound person is 0.06 meters^3
  • 0.06 * 49 = 2.94 meters^3

Meaning extra space wise,

  • Overweight => 3.92 – 2.94 = 0.98 meters^3
  • Obese => 4.9 – 2.94 = 1.96 meters^3
    • That is, if all overweight / obese were healthy weight.

And,

  • 0.98 + 1.96 = 2.94 meters^3

The two-thirds of the plane which are overweight / obese, their extra weight is taking up as much room as the healthy weight population, despite the healthy weight group having 49 less people.

-> Another way to think about this is the extra weight of the overweight and obese amounts to 5194 pounds, while the healthy weight group weighs 6909 lbs. That’s about 37 healthy weight passengers the overweight / obese group are carrying on them.

Now it’s not as simple as saying if these heavier people weren’t on the plane then we’d have 49 extra seats worth of space. There are laws for things like the size of seats (though I don’t think the FAA would be bitching if seats were made bigger!), how big aisles have to be, airlines might just pack more seats jamming the thinner people closer together, the cost reduction for saving weight is a little messy (you couldn’t just have 49 less passengers and make the same amount of money), the proportion of overweight and obese people on a plane might not be perfectly congruous to the general population (obese people tend to be poorer; flying isn’t a cheap activity), but hopefully the point has been made there is a significant amount of extra, unnecessary, weight and taken up space on a plane.

Plus, when it comes to making flying more comfortable, other things commonly cited as annoyances are flatulence and using the bathroom. While it would be intriguing to calculate how much less people would fart if nobody on board was overweight, we can appreciate it’d be less.

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