Many airbag systems contain a “black box” that records certain information about a crash. General Motors (GM) calls it a Sensing and Diagnostic Module (SDM), Ford calls it a Restraints Control Module (RCM), and Chrysler calls it an Airbag Electronic Control Module (AECM) or Occupant Restraint Controller (ORC). Although the names vary widely depending on the manufacturer and year, their basic purpose is the same: to record certain information before, during and after crashes.
The earlier systems recorded information about the status of the airbag system, including any fault codes that were present, or that had been present, and the length of time the warning lamp had been on. Some of these systems had their reliability questioned, as the data download sometimes did not match what had been physically observed in the car.
By the mid to late 1990s, GM had the most systems in cars driven by consumers that could be downloaded using commercially available equipment. That meant that accident reconstruction experts, airbag experts, and police agencies could perform their own downloads of the information contained in the black box. The availability of such equipment was important, as the information is stored in the black box in hexadecimal format requiring conversion to understand it. It still takes expertise to interpret those downloads, and not all the information stored in the black box is converted with that type of equipment. These systems typically recorded the crash severity (change in velocity over time), airbag system status, problem history and, importantly, seat belt usage.
By the late 1990s, these black boxes recorded not only the vehicle conditions at the time of the crash, but also five seconds of pre-crash data. That data includes vehicle speed, vehicle braking, engine RPM, and throttle position. Some of this data can be recorded not only for actual crashes, but also certain near-crashes where the computer algorithm experienced enough acceleration to be enabled.
By the mid 2000s, the data captured by these black boxes had grown significantly. They can record the seat position, inflator staging, what specific parameter caused airbag deployment, whether the passenger airbag was suppressed, and many other things. Some even include the air temperature at the time of the accident. Some of these newer systems are automatically tied into crash response notification if the airbag deploys, such as through uploading to On-Star.
The ownership of the data within the black box is a developing field of the law. Generally, most states treat the owner of the vehicle or the lessee as the owner of the data generated when they owned or leased the vehicle. They would then presumably have some privacy protections. However, some “fine print” in the manuals of certain manufacturers contains exceptions from these privacy protections. I expect that these exceptions will be subject to litigation in the future. The ownership of the data also surfaces in certain criminal cases involving DUI, vehicular homicide or manslaughter and other cases. Criminal courts have often required a search warrant before a police agency can download such data.
The federal regulations relating to black box data are not very comprehensive. One federal agency, the U.S. National Highway Traffic Safety Administration (NHTSA) has published rules on this topic. Incredibly, those regulations do not require a manufacturer to have a black box for their airbag system at all. However, if a manufacturer chooses do install a black box, those regulations standardize what data must be collected and how it must be accessible.
