When talking about safety and car accidents, generalizations like “90-94% of car crashes were primarily due to human error” are not helpful. It assumes that traffic accidents can only have one cause. In reality, assigning cause in traffic accidents depends on

1. Movement Before Crash Envelope – The vehicle’s movement before the pre-crash event.
2. Pre-crash event – The action or event that put the car on an unavoidable collision course.
3. Critical Reason for the Pre-crash event – The last failure in the causal chain of events and immediate reason for the crash. This can be attributed to the driver, vehicle, or environment.
4. Crash-associated factors – any other factor that increased the likeliness of a crash.

When a report estimates that human error played a role in 94% of crashes, the assignment is not intended to blame human drivers for these crashes. Instead, the number refers to how often the critical reason for an accident is due to human error.

Types of Human Error
There are several ways that human error can play a role in automotive accidents. The National Highway Traffic Safety Administration (NHTSA) created four broad classifications for what kinds of cognitive errors come into play such as

1. Recognition Error – Inattention, distracted driving, improper lookout, and other problems in perception, comprehension, or reaction. Inattention involves daydreaming or being preoccupied with other thoughts such as personal problems, family problems, financial problems, preceding arguments, and future events. Distractions can be either internal (ex. adjusting the radio or talking on the cell phone) or external (searching for a street address or looking at the scenery).
2. Decision Error – The driver’s evaluation of a driving situation is faulty. It includes decisions to drive too fast for conditions, to drive too fast around corners, to perform illegal maneuvers, to misjudge space gaps, and to have false assumptions about another’s actions.
3. Performance Error – Overcompensating by jerking the wheel, poor directional control, and panicking or freezing at the wheel.
4. Non-performance error- Falling asleep at the wheel or having a medical emergency. The driver takes no action to control the vehicle.

When the four elements of a car accident and four types of human errors are laid out, it becomes evident that broad statistics like “Humans cause 94% of car accidents” oversimplifies a complex and life-threatening issue. Human error does play a significant role in car accidents. However, not all human error should be judged as equal.