Many of us know the moment of dread. You’ve boarded the airplane and you’re in the seat. The last passengers are still coming down the aisle. There’s an empty seat next to you. The people streaming down the aisle are of assorted sizes…pray for a slim one.

But no, it has to be the unraveling 300-pound latecomer. They struggle to ram their bag in the bin. They collapse into the seat, thighs and hips barely contained, a chunky arm and an elbow spilling into your space.

That space has been meanly designed. And now, this summer, it is getting meaner, if that were possible.

Not that the FAA cares. They have just rejected a petition from the passenger activist group FlyersRights requesting that shrinking seat sizes and denser seat rows should be urgently reviewed as a hazard to safety – particularly when a cabin has to be evacuated in an emergency.

But the airlines haven’t been waiting to get the FAA’s green light. Not only are they continuing to pack more passengers into a cabin on domestic routes, but now they are doing it on long haul flights where you can be in sardine can-like seating for more than eight or nine hours.

The FlyersRights petition had stressed that the increased density of seating coincided with an epidemic of obesity among passengers – seats shrink, passengers expand.

Their contention that this constituted a new hazard to airline safety was supported in a judgment by the D.C. Circuit Court of Appeals, where Judge Patricia Millett, giving the court’s opinion, said there was “a plausible life-and-death safety concern” and instructed the FAA to address the issue.

But the agency has now pushed back hard against both FlyersRights and the court. In a six-page letter, Dorenda Baker, the FAA’s executive director for aviation safety and certification, writes, “Nothing in your petition demonstrates that decreases in seat pitch and increases in passenger girth create an immediate safety issue with regard to passenger evacuation that necessitates rulemaking.”

This is probably the most barefaced example of a public official, charged with ensuring the safety of the traveling public, insisting that no action needs to be taken when it’s self evident every day in the experience of airline passengers that action is urgently needed.

Indeed, Judge Millett had pointed out that the FAA’s claim that seat dimensions were “categorically unimportant” made no sense.

FlyersRights told The Daily Beast that they may file a new court appeal.

10 Hours in a Sardine Can

Once confined to budget airlines, what is called the densification business model for coach class is rapidly spreading to long-haul routes. A case in point is a growing change in the seating of one of the most ubiquitous long-haul jets, the Boeing 777. Originally the 777 cabin was configured for coach class with nine-abreast seating, in three rows of three sets each , divided by two aisles.

There was a logic to that layout. Boeing’s largest jet, the 747, had coach-class cabins configured for 10 seats in every row, in sets of three/four/three, creating the much unloved center row. The 747’s cabin is 20.1 feet wide.

No major U.S. airline any longer operates the 747. All across the world it is being phased out after nearly 50 years in service. Many airlines are replacing it with the 777. But the 777’s cabin is nearly a foot narrower.

That means that in order to ram a 10-seat row into a 777 cabin each seat has to significantly shrink in width. The result is painful. For example, American Airlines has 10-abreast coach seating in its 777s, with seat cushions only 16.2 inches wide. British Airways still flies its 777s with nine-abreast seats, with seat cushions of the original width of 17.5 inches.

Other long haul airlines are following American’s lead, and it may be only a matter of time when they all do, because in a coach class cabin that can add as many as 20 or more seats, which is real money.

That message hasn’t been lost on seat manufacturers. The airlines hammer home to them a basic bean-counter number: the furnishings of a cabin interior contribute at least 10 percent of the airplane’s payload. The weight of seats makes up half of that.

Thinner seats weigh less, and new materials like plastic composites can serve both as the underlying seat structure and as a substitute for separate upholstery, producing a new generation of slimmer, lighter but harder seats.

There’s more: these “shell” seats weigh even less if the backs don’t recline. Fixed seatbacks are more and more common – one manufacturer even uses the euphemism “prereclined” in promoting its version. Even if you don’t get stuck with one of these, the so-called recline on many long-haul coach seats is so minimal that it offers no real relief to the spine.

Seat width has an immediate effect on comfort, but is less of a safety issue than seat pitch. This is the space between one seat row and another, measured from the top of one seatback to the next. Pitch is far more critical in the way it affects how fast passengers can get out of a cabin in an emergency because it restricts the initial movement out of a row of seats into the aisle. And yet airlines wanting to cram in more rows of coach seats are intent on reducing pitch to a degree never seen before.

In the last decade the average pitch in coach fell from 35 to 31 inches. E ven 31 inches is beginning to feel unusually generous: quite often it is 28 inches. Risibly, the FAA claims that even with seats as narrow as 16 inches and a pitch of 28 inches there is “no evidence that current seat sizes are a factor in evacuation speed.”

This conclusion, says the FAA, “has been repeatedly demonstrated during evacuation tests.”

A New Peril: Luggage Over Life

As The Daily Beast has previously reported, these tests do not come close to replicating the actual conditions of a crash. Tests never include children, the elderly, the infirm – or the obese.

In the tests, a fully occupied cabin has to be evacuated within 90 seconds in low light conditions with half the exits disabled. The tests are conducted in a hangar free of any of the sudden impact, stress or traumatic consequences of a crash on an airfield or runway with the imminent risk of fire and explosion.

Citing recent tests the FAA claims that “passengers take no more than a second or two to get out of their seats, even from seats as narrow as 16 inches wide and installed as closely as at a 28-inch pitch.”

These tests were designed decades ago. They do not reflect changes in the way passengers now behave in an emergency. As serious crashes have become far fewer, passengers are becoming less fearful of being in a crash and, consequently, less responsive to the urgent instructions from flight attendants.

“ Fixed seatbacks are more and more common – one manufacturer even uses the euphemism ‘prereclined’ in promoting its version. ”

In several recent serious emergencies passengers, ignoring instructions, have retrieved carry-on luggage before exiting. “People are very attached to their personal belongings…that seems to overtake their desire for personal survival,” wrote Captain Peter Perry, a retired pilot, one of the authors of a study by the British Royal Aeronautical Society into passenger behavior in the recent incidents.

The study recommended that overhead bins should be locked before takeoff and remain locked until seatbelt signs are switched off, and locked again for landings and in emergencies – with a locking system directly under the control of the captain. So far no airline has taken up the idea.

How much more can what Judge Millett called “the incredible shrinking airline seat” shrink? The FAA asserts that a pitch of 27 inches represents the lower limit of what is possible. But, like the assertion that the evacuation tests remain valid, this is both casual and specious.

The FAA calculation rests on two numbers. The first is that existing regulations ensure that, whatever the other dimensions, there will always be nine inches between the front of the seat cushion and the back of the next seat – the only space that passengers can use to reach the aisle from any seat. But, accepting that this is true, they then assert that “seat bottoms are typically 18 inches from front to back, and have been so for many years.”

In fact, that dimension is discretional. There is nothing in the regulations to prevent its reduction. Just one inch shaved off the depth of the seat cushion, something that must surely be tempting to a bean counter, would produce a pitch of 26 inches.

The Daily Beast asked the FAA if a pitch of 26 inches would be acceptable.

This was one of a number of specific questions that the agency declined to answer.

Another, crucial to the safe evacuation of a cabin as the “densification” of seating accelerates, is the placing and number of emergency exits. These combine the doors that have emergency slides and the over-wing exits that are basically windows that pop out and require passengers to slide over the wing. In that case they have to use the wing flaps as slides to reach the ground – particularly hazardous in the event of an engine fire.

The FAA did not respond to the very basic question of whether the certification that a cabin has a sufficient number of emergency exits is based on a ratio that determines how many passengers must be within reach of each available exit. Clearly, when airlines increase the density of seats but the number of exits remains the same each exit is used by more passengers.

The Ultimate Crush

The ultimate test of how densely packed a cabin can be and remain safe is fast approaching. The Boeing 737-10 will take the art of passenger packing to its limit. The 737 series is the most frequently flown single-aisle jet in the world. Originally designed in the 1960s to carry about 100 passengers this forthcoming version of the 737 has been stretched to seat 230 coach class passengers.

The 737’s cabin is seven inches narrower than that of the rival Airbus A320 and 737-10s cabin will be twice the length of the original. This means that the “tunnel effect” of a tube packed with dense seating will be more acute than ever experienced before.

The 737-10 is due to enter service in 2020. Previously when The Daily Beast asked the FAA and Boeing if the 737-10’s 230-seat layout had been certified as safe in an evacuation both said that evacuation test results could not be revealed because of “the proprietary nature of the data.”

Now the FAA says “the Boeing 737-10 is not yet approved, so it has not yet demonstrated its compliance with the evacuation rules.”

But the opacity of this certification process leaves both the FAA and Boeing looking somewhat confused. It seems that Boeing believes it has met the criteria for evacuating 230 passengers by widening one set of doors, midway in the cabin, by four inches. In the published technical specifications for the 737-10 they refer to this as “the exit limit rating.”

However, in response to a question from The Daily Beast, the FAA said “exit limit rating is not a term the FAA uses and is not in the Boeing statement.”

Pressed on this, a Boeing spokesman said: “The increase in the door dimension allows for an increased passenger count per FAA regulations. For the MAX 10 [the new 737 series] the additional width supports a passenger count of 230.”

Baker’s letter to FlyersRights ended in a tone of ill-disguised irritation, sounding like an elephant that was being harassed by a pesky insect. She complained that the FAA had “limited rulemaking resources” and that “those resources will be dedicated to higher priorities.”

What could be a higher priority than passenger safety? As for resources, the FAA has an annual budget of around $16 billion and a staff of 48,000.