Washington - To recline or not to recline? Airplane 'legroom wars' are prompting growing rage in the United States, with two recent seat battles sparking a heated debate about the knee-bumping practice.
Amid the furor, one thing everyone seems to agree on is that space on passenger planes is getting scarcer and scarcer.
The question of reclining etiquette "has been a topic of discussion for many years," said Sarah Schlichter, editor in chief of IndependentTraveler.com.
"But the current uproar seems to be a sign that people are simply not happy fliers anymore."
Within just a few days, two aircraft were re-routed because of passengers fighting over a seat recline.
On a United Airlines flight between Newark, New Jersey and Denver, Colorado - which was detoured to Chicago - one passenger even used a "Knee Defender" to hold his position.
Also read: Reclining seat rage - SACCAA gives Knee Defender the OK
The $22 (R234 at R10.65/dollar) gadget consists of two clips that attach to tray table arms to block the seat in front of them from leaning back.
Sales of the gadget "in the past two and a half years have been increasing on a continuous angle," its inventor, Ira Goldman, told AFP, without giving precise figures.
"People are travelling more, on more crowded planes, the space is smaller and the airlines still provides seats that recline," added the 1.92-meter entrepreneur who says he flies 150 000 kilometers a year.
For the past week, commentary, often tongue-in-cheek, has abounded, denouncing the cramped seats and taking sides in the undeclared war between the too-tall versus the - generally inadvertent - strikes of the knee crushers in the next row.
"The war between recliners and legroomers is escalating," joked website Gawker.com on Friday.
Slate.com's Dan Kois was unafraid to take sides, saying "tilting your seat back on an airplane is pure evil."
He described a cross-country flight with "the deceptively nice-seeming schoolteacher's seatback so close to my chin that to watch TV I must nearly cross my eyes."
But in The New York Times, Josh Barro defended the recliners.
"I fly a lot. When I fly, I recline. I don't feel guilty about it," he wrote.
The 'Knee Defender' inventor, who created his gadget more than a decade ago, however, is ready to move on.
"I would be gratified if the airline industry would solve the problem that they have been ignoring for so many years," he said.
In fact, a Wall Street Journal study in October 2013 found that airlines were reducing space for economy class passengers in order to make more room for first and business class passengers, who pay far higher ticket prices.
The norm for long flights has gone from around 46cm in the 1970s and 1980s, briefly up to 18.5 inches (47cm) before shrinking down to just 17 inches (43cm) in recent years, the newspaper reported.
In comparison, legroom on a typical US train is more like 20 inches (50cm).
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To stop the legroom battles, some low-cost carriers, like easyJet and Ryanair, have removed the reclining option on short flights.
"Baggage restrictions and fees, the loss of meal services, tighter seating and more for-fee upgrades that reduce the basic experience, all contribute to more aggravation for fliers," said Schlichter.
Etiquette experts say leaning back is every passenger's right -- but beware about pushing to hard to exercise it.
"You purchase that as part of your ticket price, and no other passenger has the right to prevent you from reclining your seat," said Anna Post, one of the directors of a famous school of etiquette, the Emily Post Institute.
"We may be right, but trying to pursue being right may cause more trouble that it's worth," she said, advising passengers to lean back slowly "so you don't slam into someone."
"Sometimes just a little bit is enough to be more comfortable."