Not content with the battle between their respective aircraft, most notably the Dreamliner versus A350, the American and European manufacturers have argued over the size of economy seats on their aircraft ahead of this fall's Dubai Air Show.
Airbus is arguing that the air transport sector needs to adopt a standard seat width size of 18 inches (45.72 cm) for long-haul aircraft. Boeing said that such a seat size request was "arbitrary."
This is not a mere sideshow in the Airbus-Boeing battle, but a real fight for customers.
Lots of airlines request that Boeing use 17 inch (43.18 cm) seats in its 777-300ER aircraft, as this means the economy section can seat 10 chairs across, and more paying customers per plane is a definite plus for airlines. Airbus uses nine-abreast on the A350 and eight-abreast on the A330.
(Read more: Boeing's Dreamliner: PR fail or tech mess?)
The U.K.'s London Sleep Center, in conjunction with Airbus, recorded the sleep measurements of six healthy adults in both 17- and 18-inch seats. This involved monitoring brainwaves, eye, abdominal, chest and hip leg movement. The conclusion was that "a minimum seat width of 18 inches improved passenger sleep quality by 53 percent when compared to the 1950s 17 inch standard.
Kevin Keniston, Airbus' Head of Passenger Comfort, said following the research, "Not only does seat width make a dramatic impact on passenger comfort but there is now a growing cohort of discerning economy passengers who are not prepared to accept long haul 17 inch crusher seats and instead will choose airlines that offer better seat comfort, often turning to social media or specialist websites to determine true seat value."
Seat width is an increasingly hot topic when it comes to long-haul air travel given the changing shape of the average flyer.
According to the Centers for Disease Control, more than one-third of U.S. adults (35.7 percent) are obese, and there has been a dramatic increase in obesity across the world in the last 30 years. The World Health Organization (WHO) reported that "the worldwide prevalence of obesity nearly doubled between 1980 and 2008. According to country estimates for 2008, over 50 percent of both men and women in the WHO European Region were overweight, and roughly 23 percent of women and 20 percent of men were obese.
The AFP reported this week that a Frenchman weighing 500 pounds was told he was too fat to fly on a plane so was forced to travel by ship to return home from the U.S. The New York Daily News and other outlets also reported the case of Les Price, a 519-pound man from Wales, who was told to buy two separate seats for a return-flight and was accidentally given seats in two separate places on both journeys.
(Read more: Connected from the clouds: 3G and 4G on planes)
While the argument between Boeing and Airbus revolves around seat width, many commentators argue that seat pitch (legroom) is a more important determining factor when it comes to passenger comfort.
The AP reported that U.S. airlines such as Southwest, Alaska Airlines and United Airlines had all introduced new seas that place the magazine pocket above the tray table, away from the passenger's knees, and they use lighter-weight frames and padding that allow for more seats across the width of the plane.
This development began in 2010 when Lufthansa began using Recaro seats on its aircraft, notably the Basic Line 3520 seat, which used lighter material to reduce the weight of each seat to less than eleven kilograms, which was around 30 percent lighter than previous chair models. Thus, the BL3520's minimal weight allows airlines to lower costs by reducing fuel consumption. It also allows for more passengers on the plane, not width-wise, but length-wise.
Dr. Mark Hiller, the chief executive officer of Recaro Aircraft Seating, spoke to CNBC via email, and explained how the Recaro seat, which the company has received over 170,000 orders for since 2010, allows for more passengers as well as more legroom.
"The BL3520 offers passengers more legroom than comparable seats," he said. "This is possible due to a leaner, space-saving backrest combined with patented Recaro solutions, such as the literature pocket being positioned above the tray table, rather than at knee level. This leads to more space for passengers' legs, while enabling airlines to install additional rows of seats."
As Hiller stressed, these Recaro seats are not smaller in size, simply slimmer. What about the whole Boeing versus Airbus seat width debate? "The width of the seat has not decreased compared to previous seat models," Hiller replied. "On the contrary:the seat width is greater now due to the fact that the armrests are slimmer."
Not all airlines are "on board" with the Recaro model. While Lufthansa, Southwest, Alaska Airlines and United Airlines use slimmer seats on many aircraft, other long-haul airlines do not - and there are even differences among the short-haul firms.
Richard Goodfellow, a British Airways spokesman, said that the company was not looking at introducing slimmer seats that allow 10 chairs across on their long-haul Boeing 777 aircraft.
"We are happy with nine seats across in economy on 777 aircraft," he said via email, adding, "But I know rival airlines are starting to look again at going 10 across and some already do." He also said the company was also happy with its short-haul seat configuration as well.
On the short-haul market, easyJet announced in April that it would start using the Recaro SL3510, another slim chair model, on 14 new A320 aircraft. However, easyJet says that the new seats do not increase passenger capacity - there is still six seats per row with a total of 180 passengers per A320. Clearly the move for the Recaro seats for easyJet was down to fuel efficiency. And indeed, Airbus' Keniston said that it was slightly absurd that short haul flights could provide more space than a long haul one.
This is not something, however, being looked at by its close rival and fellow Low-Cost Carrier (LCC), Ryanair.
(Read more: Ryanair orders 175 Boeings, but CEO wants more seats)
Robin Kiely, a spokesman for Ryanair, said the company "is continually evaluating ways of improving our customer experience and service and ultimately lowering our airfares, and while we cannot comment directly on these processes, we will give any new concepts due consideration."
However, Recaro seats are being used by Norwegian, who recently announced plans to fly passengers from London to New York for £150 next year. Lasse Sandaker-Nielsen, Communications Manager at Norwegian, told CNBC in an interview: "In order to be cost-effective, you need as many passengers as possible, but also it's obviously important not to reduce the comfort on board so that's also an aspect you have to look at. As far as Norwegian goes, we've had slim seats for quite some time. We have slim Recaro seats, that give more space for legroom. Slimmer seats are still comfortable."
So next time you're on an aircraft, either long- or short-haul, check how many seats the aircraft fits in one row. And what happens if you do have a tight squeeze nestling into your chair? Recaro has the answer.
"The latest seat innovation, the CL3710, has introduced flush armrests as a comfort feature," Hiller said. "The middle armrests remain completely flush even in recline. So passengers can actually occupy two seats, if necessary."