In a letter announcing its decision, the agency said it “has no evidence that there is an immediate safety issue necessitating rule-making at this time.”
The letter was in response to a lawsuit filed by Flyers Rights, a consumer advocacy group which had requested that the FAA establish guidelines for seat dimensions. Flyers Rights argued that shrinking seats and narrow rows reduce the possibility of a safe emergency evacuation, especially for larger passengers.
However, the FAA countered by saying that current seat size is not a safety issue.
"The time it takes passengers to get out of their seats, even if those seats are relatively narrow and close together, is less than the time it takes for the emergency exits to begin functioning and for the line that begins forming in the aisle to clear," Dorenda Baker, executive director of the FAA's Aircraft Certification Service, said in the letter.
Shrinking seats
Flyers Rights said that airline seats have moved three inches closer together since 1978 as airlines pack more passengers onto each flight. Average seat width on many major airlines has shrunk by 1 1/2 inches, to around 17 inches, The New York Times reports.
The rate of obesity in the U.S. has also soared in recent decades, further compounding the issue of cramped conditions on airplanes. Today, 70 percent of adults are overweight compared to about 45 percent in 1960, according to the Centers for Disease Control and Prevention (CDC).
Regardless, the FAA cited test videos showing that seat size is not to blame for slow evacuation times. "The FAA has no evidence that a typical passenger, even a larger one, will take more than a couple of seconds to get out of his or her seat," Baker said.
The sequence of evacuation events and how closely passengers follow the safety instructions are most critical in ensuring a speedy evacuation, the FAA said.
“Passengers, regardless of their size, all use those first few seconds to get out of their seats, then either enter the aisle or wait to enter the aisle,” said Jeffrey Gardlin, the senior technical specialist for aircraft cabin security and survivability at FAA.
Research questioned
Flyers Rights has questioned the FAA’s safety evidence.
"These censored Airbus and Boeing video clips only show younger physically fit test subjects in exercise clothing stepping into the aisles. There is no showing subjects actually exiting any aircraft,” said Paul Hudson, the group’s president.
“There are no overweight, obese, elderly, infirm or children test subjects (or adjustments made for their absence), thereby excluding about 80% of US passengers. The tests are supposed to simulate panic as this is a major factor in efficient evacuation, but the videos show test subjects smiling and some laughing,” Hudson said.
“The tests are supposed to require that 50% of carry-on baggage be in the aisles but the videos show this did not happen. There is apparently no supervision or direct observation by the FAA or outside safety experts."
Flyers Rights says it will continue to fight the FAA’s stance.
"Lives are at stake here," Flyers Rights staff attorney Andrew Applebaum told NBC News. "We need to make sure that the FAA and the manufacturers are actually testing full scale demonstrations."