Brooke Shields and Jim Belushi were involved in a minor plane crash last Friday, highlighting a key safety message for pilots and car drivers: be sure to set the parking brake, or place tire chocks. There were no injuries, though egos were likely bruised.

It turns out after the twin-engined Cessna light plane, ferrying the stars to a party at Hearst Castle in San Simeon, Calif., landed safely, the pilot reportedly forgot to essentially set the parking brake. The plane rolled into a nearby parked SUV, shearing off its mirror. It’s not every day you find planes crashing into cars--and everyone living.

Parking brakes, also called emergency brakes, are required by law to be installed on cars and work on a different system than the standard brake pedal. The emergency brake system ensures the car will have some stopping ability even if the hydraulic brakes fail. Usually the emergency brake is cable operated and works only on the rear wheels.

If you have to engage the emergency brake, in a panic situation, do so slowly, as a sudden yank in a turn could cause the car to spin. (Admittedly, some people do this for daredevil entertainment, but it is unsafe on public roads.) In case of an emergency, don’t hesitate to engage the e-brake if your hydraulic brake system fails, as the less-powerful parking brake will take much longer to stop the car.

As the pilot of Brooke Shield’s plane learned, setting the emergency brake when parking is also important. In cars with a manual transmission, it provides an important backstop if you forget to leave the car in gear, and when you step on the clutch to restart the car.

Even in cars with automatic transmissions, setting the parking brake can help prevent the car from rolling downhill and make it easier to get the car back out of Park after you restart it.

However, since they’re cable operated, parking brakes have a tendency to seize if left on for long periods of time or in wet or snowy conditions. In those cases, parking on a level surface or in a garage, and leaving the car in gear can minimize the need to set the parking brake.

Maybe if Ms. Shields had been driving her Volkswagen Routan, this wouldn’t have happened.

—Eric Evarts