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How to challenge a black box report: automakers often point to data from a car's black box to 'prove' that a defect was not to blame in an accident. But this data can be highly unreliable - and is always worth close scrutiny.

Article Excerpt
If you handle automobile defect cases, sooner or later a defense attorney will wave around a page filled with rows of numbers from a black box download. The lawyer will tell you, the judge, and the jury that the numbers prove you have no case. Before that day comes, you can learn how to counter the attack, using the facts about this often misunderstood technology.

"Black box" is a popular term for an electronic device that monitors and stores information about events that take place immediately before, during, and after a collision. It resides in the vehicle's Electronic Control Unit (ECU), which controls the air bags. (1) Black boxes are formally referred to as "crash data recorders" (CDRs) or "event data recorders" (EDRs).

Defendants may say that their CDR data proves their case. But many factors can affect the validity of a black box download and call into question the accuracy of the data.

There are four basic CDR facts to bear in mind. First, not every vehicle has a CDR. Second, the devices differ wildly in the amount and quality of data they record. Third, there is no uniform downloading system: Most car manufacturers use proprietary systems, making it exceedingly difficult to download their CDR data.

Finally--and perhaps most important--no CDR issues a report. A CDR download produces a series of hexadecimal numbers representing values for various parameters. These numbers must be deciphered, either by the download software or by hand, by an analyst or technician, depending on the system.

We can thank the Bush administration's version of the National Highway Traffic Safety Administration (NHTSA) for this state of affairs. NHTSA bowed to the desires of the industry it regulates and declined to issue a regulation requiring standardization of the data recorded or the method of downloading and interpreting it.

The closest thing to a standardized system is the Vetronix Crash Data Retrieval system. Vetronix collaborated with General Motors (GM) in producing it. Since 2000, the instrumentation and software needed to read some of the data has been available to the general public for purchase. Vetronix equipment can read CDR data from most GM vehicles--and some built by affiliated companies. Since 2001, Ford has been making more of its CDRs downloadable with Vetronix gear. (2)

But aside from GM and Ford, most automakers treat CDR data as if it were a matter of national security. They have not licensed Vetronix or any other company to produce software that can work with their CDRs. To get data from a Toyota or a Honda CDR, for example, you must have the company's cooperation and participation in the download. Several manufacturers impose absurd conditions on the process.

These companies' motivations are suspect. They routinely claim that the download process is a "trade secret" and that they need to protect it from competitors. But it is unlikely that anyone would be interested in copying their systems, which are rudimentary at best.

It is far more likely that these companies want to control the download results as part of their risk-management strategy. Remember this whenever you need to perform a non-Vetronix download, and take the most extensive precautions possible to protect the data's integrity.

This is not idle speculation. One company used a single technician to perform all of its downloads. The technician invariably produced data that favored the auto company's position. Because the reports were at odds with known facts, suspicions were raised that the company had routinely substituted prerecorded data sets for the real data. Scrutiny of several downloads revealed one with a date that preceded the actual download date and two others with checksum errors. According to Geoffrey Mahon, a well-known expert on air bag sensors, the chances of a component-failure-induced checksum error is "less than 1 in 2 million hours of operation." (3)

Hits and misses

How much useful data does a CDR record? Here, too, General Motors surpasses its competitors. For...

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