Scientists have found that a car accident is typically over before were even consciously aware of it happening.
This is a reconstruction of a crash involving a stationary modern car being struck in the drivers door by another vehicle travelling at 30 mph.
0 milliseconds - An external object touches the drivers door.
1 ms - The cars door pressure sensor detects a pressure wave.
2 ms - An acceleration sensor in the C-pillar behind the rear door also detects a crash event.
2.5 ms - A sensor in the cars centre detects crash vibrations.
5 ms - Cars crash computer checks for insignificant crash events, such as a shopping trolley impact or incidental contact. It is still working out the severity of the crash. Door intrusion structure begins to absorb energy.
6.5 ms - Door pressure sensor registers peak pressures.
7 ms - Crash computer confirms a serious crash and calculates its actions.
8 ms - Computer sends a fire signal to side airbag. Meanwhile, B-pillar begins to crumple inwards and energy begins to transfer into cross-car load path beneath the occupant.
8.5 ms - Side airbag system fires.
15 ms - Roof begins to absorb part of the impact. Airbag bursts through seat foam and begins to fill.
17 ms - Cross-car load path and structure under rear seat reach maximum load.
Airbag covers occupants chest and begins to push the shoulder away from impact zone.
20 ms - Door and B-pillar begin to push on front seat. Airbag begins to push occupants chest away from the impact.
27 ms - Impact velocity has halved from 30mph to 15mph. A pusher block in the seat moves occupants pelvis away from impact zone. Airbag starts controlled deflation.
30 ms - The car has absorbed all crash energy. Airbag remains in place. For a brief moment, occupant experiences maximum force equal to 12 times the force of gravity.
45 ms - Occupant and airbag move together with deforming side structure.
50 ms - Crash computer unlocks cars doors. Passenger safety cell begins to rebound, pushing doors away from occupant.
70 ms - Airbag continues to deflate. Occupant moves back towards middle of car.
Engineers classify crash as complete.
150-300 ms - Occupant becomes aware of collision.
Mind Hacks corroborates these conclusions, stating that the start of concious awareness is typically found to be around 200-300 ms.