They’re already available on some flights, but only in business and first class.
Among the list of injuries suffered by passengers of Asiana Flight 214 were head trauma, spinal fractures and “road rash,” a tally that reflects the tremendous battering that the 291 passengers and 16 crew members endured as the Boeing 777 clipped a seawall, lost its landing gear and skidded, nearly flipping over, into San Francisco International Airport.
Remarkably, more than 120 were able to walk away, and did not require medical care. And for that, they may have had their seats, and their seat belts, to thank. After loose seats contributed to injuries in plane crashes in 2012, some airlines have reinforced the track to which seats are bolted, preventing them from getting pulled away and collapsing on passengers during rough landings or crash situations.
And the seat belts that flight attendants urge you to wear during most of the flight also helped to keep head and neck injuries to a minimum, says Dr. David King, a trauma surgeon at Massachusetts General Hospital and an assistant professor of surgery at Harvard Medical School. “Clearly for the vertical deceleration [typical] of an airplane crash, the lap belt seems to be the most important restraint,” he says.
But would a chest strap, like the ones now required in cars, have further reduced injury? “We don’t know the absolute benefit of adding a shoulder restraint to that kind of crash dynamic,” he says.
That’s because there isn’t the same volume of studies on the effects of shoulder straps and whether they improve outcomes in plane crashes as there are for car accidents. And that’s something to be grateful for, since the dearth of data is a direct result of the infrequent number of airplane crashes. “We have reams and reams of data, and decades of experience on car crashes, and on the utility of seat belts in all sorts of different crash configurations,” says Dr. Carl Schulman, director of the William Lehman Injury Research Center at the University of Miami Miller School of Medicine. “We don’t have that same data for airplanes.”
But if the lap and shoulder restraints protect passengers from serious injury in car accidents, why wouldn’t they do the same in a plane crash? For one, the forces involved in an airplane accident are entirely different from those that generally cause trauma in vehicle collisions. Car accidents (as long as the vehicle doesn’t flip) generally occur on a single, horizontal plane, and the forces are relatively predictable — they can launch a driver or passenger forward, backward or to the side. Before lap belts were mandated, the most common cause of injury or death was head trauma sustained when the passenger or driver was ejected from the car by the force of the collision.
In plane crashes, potentially life-threatening forces can also come from another plane — the vertical axis, causing spinal and skeletal injuries. And while it makes intuitive sense that more restraint with a shoulder harness would keep passengers from being jostled around and exposed to more damaging trauma, there simply isn’t the data to support that adding a chest strap would protect passengers significantly from further injury. “I find it difficult to imagine that having additional restraint offers no benefit,” says King. “The question I would ask is, ‘Is the magnitude of that benefit justifiable by the expense and the other effects a shoulder belt would have on safety?’” For example, he notes that unbuckling a shoulder harness may add a second or more to a passenger’s ability to evacuate the plane, and in the case of Flight 214, that might have meant the difference between surviving and being caught by the fire that spread through the cabin.
(PHOTO: Inside the San Francisco Plane Crash)
In addition, shoulder straps are only effective if they are anchored to a structurally sound object, which means they likely wouldn’t be helpful if they were rooted in the chair itself. Most shoulder harnesses in cars are connected to the frame of the vehicle to ensure that they don’t come loose from the impact of a crash. In planes, that would require some redesign of the seating “bench” to ensure each shoulder strap was solidly anchored to the aircraft.
And because it’s not known how much added safety benefit a shoulder harness would provide, it’s impossible for regulators to make any evidence-based assessment about whether they should be added to airplane seats. Lap belts and shoulder belts were mandated in U.S. cars after researchers showed that the odds of surviving a car crash were higher among those who used the restraints than among those who did not. “That data led to one irrefutable, absolute truth,” says King. “If you are in a car crash, wearing a seat belt will mean you are more likely to walk away alive than if you were not wearing a seat belt.”
There is a tradeoff for that benefit, however, and since seat-belt laws were enacted in almost all the U.S. states, doctors started to see a different kind of injury from crashes. “We traded being ejected from the vehicle, and perhaps getting a serious brain injury or dying, to having injuries that are sort of survivable,” says Dr. Thomas Scalea, physician in chief of the R. Adams Cowley Shock Trauma Center at the University of Maryland Medical Center.
That was the case for many of the passengers on Flight 214 as well. In addition to the head injuries and spinal fractures that the emergency-room doctors treated were abdominal injuries, which can be attributed directly to the lap belts that kept passengers strapped to their seats. These injuries are becoming familiar enough to trauma doctors that they have a name — the “seat-belt sign” — which refers to the abrasion and contusion caused by the belt on the belly.
The seat-belt sign is a red flag for potentially dangerous internal damage, says Schulman. “It’s about physics. When you have rapid compression of the seat belt pushing against hollow organs such as the stomach, colon and intestines, it can cause them to rupture, similar to a balloon.”
Most trauma physicians would much rather see these types of injuries, however, given the alternative. “The reality is that an abdominal injury from a seat belt — a ruptured intestine or liver — is more easily amenable to repair whereas a brain or neck injury is more often permanent or even fatal,” says Schulman.
What they would also like to see is better information about the types of forces their patients experience during crashes, whether they occur in a car or on a plane, says King. The medical literature is filled with case studies of victims who were involved in serious car accidents and refused medical care, believing they were fine, only to die a day or so later of undetected injuries. Traumatic injuries are almost directly related to the amount of force that a person is subjected to in a crash — the drop in velocity when a car collides with another vehicle, or with an embankment, or, in the case of an airplane crash, the sudden deceleration when a plane suspended in the air crashes to the ground. “That number alone is highly predictive of severe injury,” says King.
A relatively low change in velocity, for example, might mean that the victim likely doesn’t have internal injuries since the force of the accident simply wasn’t high enough to generate such harm. But greater and sudden changes in speed — dropping from 50 mph (80 km/h) to a standstill, for example — are more likely to cause serious trauma and require intensive evaluation and imaging tests of the brain and internal organs. Having this information would be helpful for trauma surgeons triaging victims of accidents, to determine which patients need more monitoring and which can go home. Cars currently have such decelerometers, and some researchers are working with manufacturers to develop handheld devices that EMTs can use to download the information at the accident site and relay it to emergency-room doctors along with the patient’s vital signs. Installing decelerometers under plane seats might also provide this information for plane-crash victims as well, says King.
Whether additional shoulder harnesses would have reduced some of the head or spinal trauma that some of the 19 passengers on Flight 214 who remain in critical condition experienced isn’t clear. But one passenger who walked away from the crash, Eugene Rah, told CNN he believes it might have saved him from further injury. The Boeing 777 included shoulder straps for seats in first class, and Rah said the chest belt kept him stable during impact. “If I did not have that, I would have hit the ceiling, that’s how hard [the impact was],” he said.