As airlines pack seats tighter than ever, the tests supposed to show that passengers can get out alive in a crash are woefully out of date. The FAA won’t make the results public, and a court warns there is “a plausible life-and-death safety concern.”

For years the airlines have been allowed to steadily shrink the size of coach class seats and the space between seat rows without regulators considering the impact of this on safety. A Daily Beast investigation has found:

• The tests carried out to ensure that all the passengers can safely exit a cabin in an emergency are dangerously outdated and do not reflect how densely packed coach class seating has become—or how the size of passengers has simultaneously increased;

• No coach class seat meets the Department of Transportation’s own standard for the space required to make a flight attendant’s seat safe in an emergency;

• Neither Boeing nor the Federal Aviation Administration will disclose the evacuation test data for the newest (and most densely seated) versions of the most widely used jet, the Boeing 737.

In a case brought by the non-profit activist group Flyers Rights and heard by the U.S. Court of Appeals for the District of Columbia Circuit, a judge said there was “a plausible life-and-death safety concern” about what is called the “densification” of seats in coach. The court ordered the Federal Aviation Administration to respond to a petition filed by Flyers Rights to promulgate new rules to deal with safety issues created by shrinking seat sizes and space in coach class cabins.

Furthermore, the court complained that the FAA had used outdated studies to argue that no change was needed in the way emergency evacuation tests are carried out—and, at the same time, had refused to release details of the test results because they involved proprietary data.

The Daily Beast has since examined more than 900 pages of Department of Transportation documents and FAA regulations that address the way airplane cabins are configured to ensure rapid evacuation in an emergency. All of the tests designed to achieve the fastest possible evacuations were devised decades before the appearance of budget airlines greatly increased the density of seating and, in particular, before the size of seats shrank and the space between each row of seats similarly shrank.

Outdated, Unrealistic Tests

The protections that are essential to surviving an air crash are tested in two different ways. The first are static tests to demonstrate that a fully occupied airplane can be evacuated in 90 seconds. The second are dynamic tests using 170-pound anthropomorphic dummies to test the design of seats and other physical components in a cabin. These include, for example, the effects of blunt trauma impact when a passenger’s head strikes the seatback in front of them.

For a static-evacuation test all the seats in a cabin are filled with volunteers. The FAA regulations specify: “Test subjects must be naïve [sic] and meet the specified demographics (age, gender etc) to ensure a representative passenger load, while at the same time not subjecting people to undue risk.”

In fact, the tests do not come close to replicating the actual experience of a crash. Firstly, the volunteers (and flight attendants) are mentally prepared for what is going to happen. They do not experience any of the sudden alarm and stress that can precede a crash in a declared emergency. Secondly, the airplane cabin is in a hangar, free of any of the traumatic consequences of ending up on an airfield or runway in an airplane that is seriously damaged and when there is an imminent risk of fire, smoke, or an explosion.

There could not be a better illustration of how detached from reality these tests are than the example of Qantas Flight QF32. This involved the largest airplane in the world, the Airbus A380. Normally this super-jumbo carries around 550 passengers but its evacuation tests were carried out using its maximum capacity of 853 passengers, according to the 90-second rule with only half the exits available.

On November 4, 2010, Flight QF32 suffered a catastrophic engine failure on its climb out from Singapore en route to Sydney, Australia. Shrapnel from the engine tore through vital systems and seriously degraded the pilots’ ability to control the airplane.

There were 469 people on board. The pilots did a remarkable job getting the jet back down on the Singapore runway, but were faced with multiple failures. One engine could not be shut down and, most dangerous of all, the brakes had become red hot from the strain of stopping the airplane, just short of the end of the runway. There was a high risk of fire if jet fuel reached the brakes. The captain and crew decided it was far too dangerous to evacuate passengers with a fire risk on the runway and with limited exits available. It was 52 minutes before the first passengers were evacuated, via stairs.

In reality the static tests are a prescribed exercise in reaching goals set by engineering standards—to demonstrate, for example, that there is a sufficient number of doors and that the doors are correctly placed to get passengers out according to the 90-second rule. The evacuation must be carried out with only half of the exit doors being available, and in poor light. This has been the basic standard for all evacuation tests since the dawn of the jet age in the late 1950s and does, at least, provide a baseline to ensure universal compliance.

The dynamic tests are seldom seen or referred to because they do involve many proprietary details, for instance advances in the design of seats. Dynamic tests are carried out by both the makers of the seats and the airplane manufacturers. As a basic requirement the seats must be able to withstand forces of up to 16 times the force of gravity. Getting a new seat certified for use can cost more than a million dollars.

The two most significant changes in seat design are a move away from bulky upholstered seats to slender shells and the addition to seatbacks of video screens for in-flight entertainment. In fact, DOT documents reveal that testing seatbacks equipped with video screens for blunt trauma impact destroyed so many of the expensive screens that the FAA allowed the manufacturers to substitute cheaper replicas.

It would be impossible for any test, static or dynamic, to accurately mimic an actual crash. No two crashes are alike. They can occur in a wide range of conditions, ranging from a blizzard to desert heat, from a hard runway to splashdown in the sea. In the end, the best that can be achieved by testing is to make sure that, at the very least, the physical layout of a cabin doesn’t actually add to the problems of getting out as fast as possible.

And this is where the new density of seating becomes an urgent concern. The D.C. court’s judgment specifically called out the FAA for ignoring the way airlines are packing more passengers into narrow tubes. The court pointed to something that is now obvious to anyone boarding an airplane: “a pattern of placing ever larger passengers in ever smaller seats with still less space between them.”

Seats So Tight They Risk Head Trauma in Crash

In bringing the case, Flyers Rights documented what this contraction of space means in actual inches. Two measures are particularly critical in deciding the ease (or otherwise) of evacuation: the dimensions of the seats themselves and the extent of the space between seat rows, measured from the top of one seatback to the next, called pitch. Flyers Rights said that in coach the pitch has decreased from an average of 35 inches in the early 2000s to 31 inches today—and in an increasing number of cases it has now shrunk to 28 inches. In the same period average seat width has shrunk from 18.5 inches to 17 inches.

An FAA spokesman told The Daily Beast that it couldn’t discuss how specific airplane manufacturers tested for different seating densities but he did say that “manufacturers have demonstrated full-scale emergency evacuation of airplanes with seat pitches as low as 28 inches. In no case did the seat pitch have an effect on the outcome of the test.”

However, Judge Patricia Millett, giving the court’s opinion, commented that the FAA’s claim that seat dimensions were “categorically unimportant to emergency egress” made no sense.

“Maximum occupancy is not an adequate proxy for cabin seat or passenger dimensions,” she added. “Because planes commonly include different seating classes like first class, business class, and economy plus, limiting the number of seats in an aircraft does not limit the seat pitch and width in all of the seats, and especially in the ordinary economy class seats. That means that economy seating pitch could decrease to levels that could impede emergency egress, while the pitch and width in the first class and business class seats would not.”

Paul Hudson, the president of Flyers Rights, expanded on this point to The Daily Beast, suggesting that the disparity in the density of seating between classes of cabin was “a Titanic waiting to happen,” comparing the plight of passengers in coach with the plight of steerage class passengers on Edwardian-era steamships where priority in an emergency was given to first- and second-class passengers.

Furthermore, Hudson is concerned that the space between seat rows has become too tight for passengers to adopt the brace position illustrated on the emergency evacuation instruction cards supplied to every passenger, in which passengers are told to lean forward and cover their heads with overlapping hands to lessen the risk of head and spine injuries in a violent crash landing.

While The Daily Beast could find no data in the FAA regulations about the minimum space required between seat rows for a passenger to be able to adopt the brace position, the DOT’s guidance for the dynamic testing of seats does include a pertinent graphic.

It shows the requirements for the seats used by flight attendants during takeoff and landing and it specifically delineates what it calls the head strike zone—the space that must be kept clear so that, in the event of an impact, the occupant’s head avoids contact with an adjacent seat. The zone must extend for at least 35 inches from the axis of the seatback and seat cushion—not from seatback to seatback.

With the most generous pitch in coach at 32 inches, according to a Flyers Rights court briefing, no coach seat meets that standard.

Another factor that plays a crucial role in evacuation is the width of the aisle. The aisle is the only pathway from seat rows to the exit doors. Like the regulations dictating static tests, the regulations that determine aisle width have not changed in decades. For airplanes carrying 20 or more passengers the minimum width is 20 inches—not much more than the width of a coach class seat.

Although the FAA contended in the court case that seat dimensions had no influence on evacuation it did allow that “increased passenger width had the greatest effect on exit speed of all the variables tested.” The agency gave no data source for this euphemistic discovery of the obesity epidemic but, at the very least, it serves as a warning that the thinking about aisle width, like the dimension of seats, has not adjusted to the new reality.

For example, Flyers Rights submitted anecdotal evidence from passengers indicating that “exit speed” is actually a good deal longer than the 90 seconds demonstrated in tests—passengers spoke of taking three or four minutes to get to an exit.

Evacuation is most critical in airplanes with a single-aisle; in a twin-aisle widebody jet there is an alternative if one aisle gets blocked.

In 2015 single-aisle airplanes accounted for roughly two-thirds of global airline fleets. Budget airlines drive this pattern because the airplanes are the ideal size for their business model, carrying between 160 and 200 passengers over short to medium distances. Boeing and Airbus provide the two budget airline mainstays, the Boeing 737 and the Airbus A320. Given the new density of seating in coach, there are several reasons why, of these two airplanes, the 737 should be the center of concerns about ease of evacuation.

One Aisle, Double the Passengers

The 737 was designed in 1964, making it the oldest design of any airplane still in wide use throughout the world. The first version was 94 feet long and carried 124 passengers. Boeing’s newest version, the 737MAX10, has been stretched to 143 feet 8 inches to accommodate, at maximum density, 230 passengers. Although the length of the cabin has increased so dramatically the width has not because that would have called for a completely new design. The width remains at 11 feet 6 inches, giving the 737MAX10 the tightest coach-class layout. (The cabin of the Airbus A320, designed in the 1980s, is 7 inches wider. Optically and physically that difference is telling when there are 230 seats, producing a tunnel effect.)

Although many things have evolved in the design of the 737 since 1964 (including new wings and tail surfaces and a succession of engine upgrades) the basic structure of the fuselage has remained largely as it was. There have been some small changes in the type of aluminum used, making it more resistant to corrosion, and the manufacturing method has been modernized.

But in terms of its structural integrity the fuselage still reflects the best that could be achieved in the mid-1960s, not now. The record of how the 737’s fuselage behaves in crashes shows that it has a tendency to break open on impact and it is obviously a lot more challenging for passengers to evacuate from an airplane if its cabin tears open. This curtails the number of evacuation slides that are useable, and some passengers are violently exposed to the elements while still strapped in their seats.

The best way of demonstrating the importance of this is to compare the 737’s record in crashes with that of Boeing’s best-selling widebody jet, the 777.

The 777 was designed in the early 1990s. The technology brought to bear on the design of its fuselage reflects everything that Boeing’s designers had learned by then about what was needed to make an airplane cabin more able to retain its structural integrity in a crash, which is fundamental to the survivability of passengers.

How well they learned could not be more spectacularly demonstrated than in the case of Asiana Airlines Flight 214 in which a 777 came close to catastrophe in a crash landing at San Francisco International Airport on July 6, 2013.

After a mishandled approach due to confusion among the pilots the 777 was too low as it reached the runway and hit a sea wall at around 180 mph. The landing gear was ripped away and the rear of the fuselage, including the tail, separated and fell to the runway as the remainder of the airplane careened on out of control along the runway.

The left engine separated from the wing and for a moment the airplane was airborne before its nose gear hit the ground again and acted as the pivot for a wild 330-degree gyration, still at high speed. As the airplane finally came to rest on rough ground near the runway, part of the lower right fuselage was peeled open.

Investigators from the National Transportation Safety Board later concluded: “This accident included multiple severe impacts that exceeded the design and certification requirements.”

On board were four pilots, 12 flight attendants, and 291 passengers. Only three passengers died, in the rear rows 41 and 42, when the rear of the fuselage broke away. Three flight attendants seated in the rear were thrown out, still strapped to their seats, but survived. Amazingly, 109 passengers walked away, while 182 were hospitalized, some with serious spinal injuries.

Several things combined to avoid disaster. The engine that broke away was designed to do just that. The main fuel tanks did not rupture (at the end of a long flight from Seoul the fuel levels were low) and consequently there was no immediate engulfing inferno.

The investigation by the NTSB noted how well the cabin interior had protected passengers as other parts of the airplane were seriously damaged.

In effect, the Boeing designers had made the 777’s cabin a more secure cocoon. Within the outer shell of the fuselage the cabin had a separate system of ceiling and wall panels, bulkheads, and a floor that withstood violent forces from several different sources: deceleration, and vertical and sideways forces during the wild gyration. The impact to the lower right of the fuselage had, by chance, absorbed energy, working like the crush zone of a car.

Many seats were partially displaced by the impact, the legs of some had broken away from their floor tracks and others had legs bent to the left, but the aisles remained clear and the overhead luggage bins remained intact. A number of passengers were unable to evacuate from their seats because of injuries but they were rescued by the airport’s first responders.

Fifteen minutes after impact the oil tank serving the right engine did catch fire and produced thick, toxic smoke that would have been fatal if inhaled. This fire eventually destroyed two-thirds of the right side of the fuselage.

A more recent 777 crash at Dubai last year also showed the robustness of the design. Hit by wind shear as they were about to touch down the pilots aborted a landing and attempted to climb clear of the runway but, without sufficient power, the airplane sank back and hit the runway and skidded for 2,600 feet before coming to a stop. All 300 people aboard evacuated. Twenty-four passengers were injured, one seriously. Nine minutes after the crash the central fuel tank exploded, killing a firefighter.

Aborted landings are rare, but research carried out by Airbus shows that about 30 percent of them result in a fatal crash, often with weather as a factor.

In survivable crash landings the 737’s fuselage, unlike that of the 777, has sometimes cracked or broken into several parts:

In 2008 a Continental Airlines flight taking off from Denver encountered wind shear and ice and slewed off the runway. The cabin cracked immediately behind the wings. All 115 on board survived but 38 passengers were injured, two seriously.

In 2009 an American Airlines 737 left the runway while landing during a rainstorm at Kingston, Jamaica, and its fuselage broke apart at points in front of and behind the wing. There were 85 minor injuries.

In 2010 a 737 flown by Aires Airlines landing during a storm at San Andres Island, Colombia, made a heavy landing and the fuselage broke into three pieces. One passenger died and 30 were injured.

In 2011 a Caribbean Airlines 737 left the runway while landing at Georgetown, Guyana. The fuselage broke apart just ahead of the wings. Seven passengers were injured.

In 2013 a Lion Air 737 on approach to Bali International Airport crashed into shallow water short of the runway. The fuselage broke apart behind the wings. All 108 people aboard survived but 46 were injured, four seriously.

In serious crashes where the fuselage of a 737 has remained intact, as in the case this year when a Peruvian Airlines 737 crashed on landing at Jauja, Peru, evacuation can be swift. Video taken by a passenger shows that 141 people were efficiently and rapidly evacuated from the cabin before it was engulfed by fire, with only 39 minor injuries.

The 737 is the most ubiquitous airplane ever built: There are more than 6,500 in service and more than 30 percent of all commercial flights are by various models of the 737. The two largest budget airlines, Southwest in the U.S. and Ryanair in Europe, built their business models around the 737’s operational efficiency and durability—most budget airlines’ 737s make as many as seven flights a day, with an average turnaround time between flights of 40 minutes. Given this frequency of use the 737’s accident rate is relatively low: one for every 2.5 million hours flown.

Airlines love the latest models of the 737. A leap in engine technology has made them as much as 20 percent more fuel efficient than earlier models and they emit 20 percent less carbon dioxide and 50 percent less nitrogen oxide. The engines are also 40 percent quieter. Airlines operating the 737’s principal competitor, the Airbus A320, often have seating with the same high density pitch of 28 inches but the 737 is cheaper to operate and Boeing often gives huge discounts on large orders to sweeten the deal further.

And yet, for all its refinements, the 737 remains a hybrid of new and old technology. For example, the cockpit combines a 2015 system of digital visual displays for the pilots with a mass of switches, buttons, and knobs of 1960s vintage. The electrical and air conditioning systems are similarly little changed because they are part of the plumbing of the original fuselage.

Tests on World’s Most Popular Plane Kept Secret

Pushing this singular mix of vintage and advanced parts to the extreme where it can carry 230 passengers was possible only with the consent of the certification system that every airplane has to meet—and, in this case, the emergency evacuation tests were crucial. Neither the FAA nor Boeing will make public the results of tests specific to the latest versions of the 737. Both cite as the reason “the proprietary nature of the data.”

However, Boeing did respond to questions from The Daily Beast. A spokesman said, “The public can be assured that Boeing substantiates the evacuation capability of our airplanes using the maximum allowable number of passengers, which is significantly higher than what airlines typically use in their operations.” He also said that testing included “narrower than typical” seats and a 28-inch seat pitch.

An FAA spokesman explained that airlines themselves can test emergency evacuation procedures using a “partial demonstration” in which only a section of the cabin is used with typical seating—if the airplane manufacturer has already carried out the full-scale tests. Boeing’s spokesman said “the FAA may, in certain circumstances, allow the evacuation capability of the airplane to be substantiated by a combination of testing and analysis.”

The fact is that nobody can realistically know how long it would take to evacuate that many passengers from a 737 in a crash—that is, without a crash actually happening. Evacuation testing in its current form is not a real world experience: It has become a charade that gives cover to regulators, airplane makers, and airlines.

The airlines have now reached the point of reducing the space allotted to each passenger in coach to the barest minimum. In terms of comfort the result is often barely tolerable. In terms of safety the consequences could be dire.

It is always difficult to get people to recognize the potential for disaster if the disaster has yet to happen. To be sure, it is beyond dispute that flying is far safer than it was only a few decades ago. According to statistics, you would have to take one flight a day for 55,000 years before being in a crash. And an essential part of that advance is the greatly increased chance of survival in serious crashes. The NTSB and the European Transport Safety Council both put the chance of survival at more than 90 percent—but that is for crashes that do not result in an immediate fire or explosion.

The danger now is complacency. Accidents frequently expose a pattern of converging factors that is not detected until it is too late. The convergence of the “densification” of coach class seating and the expansion in the girth of passengers has all the signs of introducing a new level of risk. Flyers Rights wants the FAA to place a moratorium “on any further reductions in seat size, width, pitch and padding and aisle width” and to appoint an advisory committee or task force to set new standards for seat and passenger space.

The court gave the FAA until Dec. 28 to respond.