Mary Proctor of Lanham drove up the on-ramp from Pennsylvania Avenue SE last Thursday night and prepared to merge with the traffic on northbound Interstate 295.

Normally, the best way to do that is to step on the gas sharply, so you match the speed of the freeway traffic as quickly as possible. So Mary stepped--right into a nightmare.

The gas pedal on her 1978 Monte Carlo stuck. Panicking, she slammed on the brake. That slowed the car slightly but didn't stop it. Panicking further, Mary tried to unstick the pedal by stomping on it as hard as she could a few times. That succeeded only in making the car go faster.

Finally, Mary did the only thing she could. She steered off the road onto the right shoulder. Traveling at perhaps 70 miles an hour, she banged the right side of her car against the guard rail once, twice, six times, until the friction slowed the car to the point where Mary could use the emergency brake to stop.

But scraping against the rail caused her car to catch on fire. Luckily, Mary was able to bail out before she was injured. But there sat her car, going up in flames. What to do?

Wait for human nature at its best to arrive, as it turned out. Within ten minutes, three drivers had stopped to see if they could help. The first two didn't have fire extinguishers in their cars, so they couldn't. But the third was an off-duty D.C. policeman, who did have one. A minute or so of spraying, and the fire was out.

The story has several morals.

First, all of us should carry fire extinguishers in our trunks. Most car fires start in, and are confined to, the engine. Since the trunk is at the opposite end of the car most of the time, drivers can usually reach an extinguisher without endangering themselves. In addition, extinguishers are relatively cheap. Reliable models start at about $25.

Second, all of us should check our accelerators, now and regularly. Better yet, have a mechanic do it. None of us needs to be put in Mary Proctor's position. And don't assume there'll be warning of a faulty spring. Mary says the accelerator on her car had never stuck before.

Third, take the advice of police officers and manufacturers. If your accelerator sticks, the safest thing to do is to throw the gearshift into neutral immediately. Then get over to the side of the road, where you can coast and brake to a safe stop.

Understandably, shifting to neutral didn't occur to a frightened Mary Proctor. She has a "totaled" car to serve as a reminder if, Heaven forbid, there's a next time.