WASHINGTON - If that airline seat is a tad snug for your burgeoning backside or the distance between rows makes you claustrophobic and fearful that a bit of reclining could crush your knees, blame it on the money-hungry airline.Thatís the message from the Federal Aviation Administration, which said as emphatically as skillfully-fashioned legal jargon can describe Tuesday, that squeezing the nationís expanding bottoms into shrinking airline seats is not their problem.The FAA did so despite a demand for federal regulation of seat size, a lawsuit brought by the consumer group Flyers Rights, and a judgeís order that the agency reconsider its position.Reconsider, the FAA did, concluding that there is "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" in the case of an emergency.Seat width on many major airlines has shrunk from about 18.5 inches to 17 inches. Seat pitch - the distance between your seat and the one directly in front of you - has decreased from an average of 35 inches to 31 inches, and on some airlines it has been reduced to 28 inches.While seats have grown smaller, the Centers for Disease Control and Prevention says the average weight of a woman these days is equal to that of the average man in the 1960s: 166 pounds. The average man now weighs almost 196 pounds. Men pack a 40-inch waistline. Women tickle the tape around the waist at 38 inches.That has caused a lot of grumbling from passengers - some of whom are members of Congress, who spend a lot of time on planes - and led to a demand that the FAA do something about the unwelcome squeeze.The FAA said no, itís not going to go through the formal rulemaking process for something that ought to be sorted out between the passengers and the airlines.The Flyers Rights Education Fund figured that suing the airlines was a fools errand, so they petitioned the court to order the FAA to get involved. The FAA said it would rather not, pointing out that seat spacing did not affect the safety or speed of passenger evacuations.That FAA ruling resulted in what Judge Patricia Millett of the U.S. Court of Appeals for the District of Columbia Circuit called "the Case of the Incredible Shrinking Airline Seat.""Aircraft seats and the spacing between them have been getting smaller and smaller, while American passengers have been growing in size,í" Millett ruled from the bench, ordering the FAA to think again.Flyers Rights President Paul Hudson said the group is absorbing the FAA documents, which arrived Monday night, but that a second appeal to the court seemed likely."This response is mainly couched in the idea that they donít know of evidence that larger passengers in smaller seats, and older passengers, would be able to get out as quickly as smaller passengers, younger passengers," he said. "Weíll be reviewing it, but itís likely weíll be going back to the appeal court."Others, however, said that the decision is likely to embolden airlines."This is like a carte blanche to let the airlines do whatever they want. It is a free ticket to narrow seats and put in more rows of passengers," said Brent Bowen, a professor at the Embry-Riddle Aeronautical Universityís Prescott, Arizona, campus. "I think itís causing people to be grumpy, irritable, and literally thereís cases where people donít fit in the seat in the back of airplane. Iíve seen it and itís quite embarrassing when you donít know that some seats are bigger than others."Were it not for a judgeís order, the FAA would have been happy to avoid the whole question of expanding buttocks and shrinking seat sizes. The FAA views itself as a safety agency, one that does its best to ensure that airplanes are well-built and conduct themselves safely.The agency, for example, is responsible for the flight attendantís safety message about how seat belts work, even though virtually everyone knows that without being told to "insert the metal fitting into the buckle and tighten by pulling on the loose end of the straps. To release your seat belt, lift up the buckle end marked Ďliftí."More to the point, the FAA requires that everyone seated in an exit row - beside a door that can be opened - understand their duties or are given the chance to take a seat elsewhere.And then there are a couple of the "unlikely events.""In the unlikely event of a loss of cabin pressure, an oxygen mask will drop from the overhead panels" and "In the event of a water Ďditchingí you will find a life vest underneath your seat."(Cue to flight attendant who shows how blowing into the red plastic tube will inflate the vest.)The FAA requires all of that, plus that your "tray tables must be in the upright and locked position" for takeoff and landing, "seat backs in the upright position" and "your carry-on luggage must be stowed underneath the seat in front of you."All that is so that you can evacuate should there be an "unlikely event."Thatís all about safety, and the FAA does care about whether youíre able to get out of your seat and aisle in times of emergency.It has been less inclined, however, to tell airlines about the creature comforts on their planes. If an airline decides to shrink its seats, and that does no harm to a potential evacuation, the FAA would leave it up to the passengers to complain.The FAA spelled that out Tuesday in five-page letter to Flyers Rights accompanied by a seven-page document by Jeffrey Gardlin, the FAAís senior technical specialist for aircraft cabin security and survivability.The letter and Gardlinís document say: "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."The FAA said it has videos available that demonstrate this."The key is that the time it takes to stand up from oneís seat, even if the seat is relatively narrow and installed at a 28-inch pitch, and even if the passenger is relatively large, is less than the time it will take to get the emergency exits open and functional."In other words, the FAA says seat sizes do not impede the need for passengers to jump from their seats and make their way to an exit.Bowen, who for 28 years has put out the Airline Quality Rating, says most airlines "automatically put you in the worst seats and you have to buy your way out.""They have a strategy only to put you in the middle of a row in a tiny seat in the back of the aircraft," he said.Frequent fliers know how to work the system to find the best seat, he said, but "itís going to have a severe impact on the people who donít fly very much.""Itís the infrequent flier thatís going to be upset about this," Bowen said.The only solution to the seat squeeze, he says, will come if Congress steps in."Thereís no alternative, because the airlines are not going to set a reasonable standard," Bowen said.Bowen said his students recently studied a report entitled "FAA policymaking: blood on the runway.""Until we have a plane load of people that are trapped inside and unable to get out, they probably wonít act," he said. "Thatís what it takes for the FAA to act: blood on the runway."