Thousands of people have survived crashes because of their frontal airbags, but an early problem involved inflation when the airbags should have stayed stowed away. Design changes addressed this (see "Occupant deaths from inflating airbags have been all but eliminated," Aug. 6, 2005), and now the issue is whether people are being left unprotected in crashes because their frontal airbags failed to inflate. New Institute analyses indicate a potential problem, but a limited one.
The latest controversy began with an October 2007 Kansas City Star report that at least 1,400 occupants died during 2001-06 in frontal crashes in which their airbags didn't inflate. Based on data from the federal Fatality Analysis Reporting System (FARS, a census of fatal crashes on U.S. roads), the Star implied that more than 200 deaths per year are being caused by airbag system failures.
Responding to the Star, Institute researchers have taken a closer look at FARS data plus information from a sample of crashes in another federal database, the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS), finding that all but a few of the apparent airbag failures are either FARS errors or cases when airbag inflation wouldn't have been expected.
According to FARS, 18 percent of front-seat occupant deaths in frontal crashes of 1994-2006 models during 1998-2006 involved airbags that apparently failed to deploy. However, 54 of the nondeployment cases also are included in NASS/CDS, and in 25 of these cases NASS/CDS reports that the airbags actually did inflate.
"FARS is useful, but the police who supply the data don't always note correctly whether an airbag deployed," says Elisa Braver, the Institute's senior epidemiologist. "This is why sometimes you have to dig deeper to see what actually happened in a given crash, and NASS/CDS is a good source for a deeper dig. The Star reporters simply relied too much on FARS."
The NASS/CDS sample includes more detailed information on crashes than FARS. The information is collected by trained investigators instead of police officers who have to juggle competing duties at crash scenes.
To get a handle on the true extent of the airbag nondeployment problem, Institute researchers reviewed 628 frontal crash deaths included in both FARS and NASS/CDS. The airbags inflated in 548 of these cases. Of the remaining 80 deaths, 26 occurred in vehicles so thoroughly destroyed in fiery crashes that the NASS/CDS investigators couldn't determine whether or not the airbags inflated. In another 11 cases the airbags had been switched off or removed from the vehicles.
This leaves 43 potential airbag failures, which Institute researchers studied in detail. The airbags wouldn't have been expected to inflate in 25 cases because, for example, the vehicles underrode trucks, bypassing the airbag sensors, or they rolled over. Airbags inflate only when sensors detect a frontal crash.
In 11 cases, the extent of damage to the fronts of the crashed vehicles indicates the airbags would have been expected to inflate. In 6 other cases the airbags possibly should have inflated (impact severity was borderline). These deaths in the NASS/CDS sample translate into an estimated 50 to 100 deaths per year involving potential airbag failures. It's 1 to 2 percent of all deaths of front-seat occupants in frontal crashes.
"This isn't as many deaths involving potential failures as the Star implied, and it's possible that even these nondeployments were associated with crash complexities we couldn't account for," Braver explains. "Still it's hundreds of deaths during the years of our study, and we need to see if they could have been avoided."