BIRMINGHAM, Ala. --- The driver of a bus carrying 44 children on a field trip lost consciousness at the wheel, but a teacher's quick actions averted a head-on collision last Friday, March 28, the Birmingham News reported.

Amy King, a math teacher traveling on the bus, grabbed the steering wheel to prevent the bus from careening into oncoming traffic. The driver, however, was thrown through the windshield and is in serious condition. Twenty passengers were taken to the hospital with injuries.

The bus sideswiped 200 feet of guardrail before it came to a stop upside-down in a drainage ditch about 30 miles northeast of Birmingham.

Just how common is it for a driver's illness to lead to a collision?

According to the Los Angeles Times, National Highway Traffic Safety Administration (NHTSA) data indicate that in 2005, there were 521 fatal crashes in which illness was a factor in one of the drivers. The collisions killed 422 of the ill drivers, 65 occupants of the ill driver's vehicles, 61 occupants of other vehicles, and 15 pedestrians or bicyclists. A total of 563 people were killed, more than 1 percent of the total highway deaths that year. The medical conditions included seizures, heart attacks and fainting, among other problems.

Yet, surprisingly, few driver education programs or DMV materials even address the issue of a passenger taking control of a vehicle after the driver suddenly becomes too ill to operate it. There are no statistics available that show how often a passenger's actions prevent an accident in such a situation.

Of course, no standard emergency procedure can apply to every situation. But when queried by the L.A. Times, a spokesman for the California Highway Patrol advised that passengers should stay calm and not turn off the engine, since that would also disable the power steering and brakes. A passenger would also have to decide in an instant whether he or she would need to unfasten their seat belt in order to reach the brake pedal or pull the driver's foot off the accelerator. The vehicle's center console configuration can make it more difficult to take control of the vehicle without unbuckling.

This scenario may sound like something you'd only see in the movies, but NHTSA data prove that it can happen in real life, too.