As he placed his 3-year-old daughter, Dana, into her car seat one rainy afternoon in September, Bryan Hutchinson snapped the buckle closed and tugged her safety belt to make sure she was protected -- and then he checked it again, just to make sure.

Minutes later, as his wife, Michele, drove through a storm on a curvy road near Olney, she lost control of the car and collided head-on with a pickup truck. In the violent collision, the seat designed to save Dana's life flipped forward, and Dana's head smashed against the dashboard.

Two days later, Michele Hutchinson cradled Dana in her arms one last time before the child was removed from life support.

Dana's death was devastating to the Hutchinsons, but they were even more crushed to learn it could have been prevented if they had installed the car seat correctly. The seat belt in their 1991 Mercury Cougar was not designed to secure their child seat, which could have been secured with a free supplementary buckle provided by Mercury to fasten the lap belt to an anchor on the floor, according to police and federal officials.

"It's every parent's worst nightmare," Bryan Hutchinson said. "We weren't careless. We did everything we thought we were supposed to do. We ... don't even let {our children} ride in other people's cars -- not even with their grandparents."

The Hutchinsons were angry and frustrated to learn their tragedy was not an isolated occurrence. Although child seats have saved countless lives since they became mandatory for transporting small children, the National Highway Traffic Safety Administration estimates that more than 50 children are killed and thousands more injured each year as a result of improper use. About 5 million child seats are in use, the government said.

"When correctly used, child seats are 71 percent effective in preventing fatalities," NHTSA Administrator Ricardo Martinez said. "However, we are still saving only about half as many lives as we could."

Since 1985, child seats have been required by law in all 50 states and Puerto Rico, with fines ranging from $10 to $500 for violations. The District and Virginia require children younger than 3 to be placed in safety seats, and Maryland's law applies to all children younger than 4.

But although auto-restraint systems have become easier to use and more comfortable for adults during the last decade, child-restraint systems have become more complicated.

Different types of seat belts and child seats require different modifications. In some instances, seat belts can be modified with a simple I-shaped locking clip. In others, car owners must install a supplementary belt.

Child seats "are deceptively simple-looking devices," said Sharon Freimuth, spokeswoman for Century Products Co., of Macedonia, Ohio, one of the nation's largest manufacturers of child restraints. "I know people don't want to read the manuals -- I don't want to read them. But there are some kinds of belts that can't be used with car seats. They won't hold the seat in tightly enough, and they're going to move, and the kids are going to get hurt."

Martinez said many parents have a tendency to disregard manuals and try to install child seats as they would assemble a Christmas toy.

"They ... figure they're smart enough to do it without reading the instructions," Martinez said. "When they are all done, it looks good, but there are some extra pieces left over. That may be okay with a toy but not a device that can save a child's life."

Experts said many injuries and deaths, including Dana Hutchinson's, are not the result of parental negligence. Instead, they blame complex instructions and subtle differences between restraint systems that make it difficult for drivers to know for sure whether a child really is safe.

"I think the biggest problem with infant and child restraints today is misuse," said Brian O'Neill, executive director of the Insurance Institute for Highway Safety. "Often it is misuse based on lack of knowledge, and unfortunately, there are so many different seat belt configurations in the marketplace that it is impossible to be assured that any given seat can be properly put in every car just by using the belts alone."

Experts said the most foolproof method of protecting children in cars is to use a manual lap belt, which can generally be found in the center back seat. Those belts generally are anchored far enough behind the back seat to prevent the child seat from pitching forward in a crash.

Stephanie Tombrello, executive director of the advocacy group SafetyBeltSafe U.S.A. in Inglewood, Calif., said her volunteers are astounded by the widespread misuse they see when conducting safety-seat checkup clinics for parents.

"These are people who are highly motivated, concerned about safety, and most of them come for an 'Attaboy, you're a wonderful parent' response," Tombrello said. "We find that 75 to 90 percent have some problems" that could result in serious injury or the death of a child.

For example, infants placed in rear-facing seats never should be secured in the front seat of a car with a passenger-side air bag, which can injure the child when it inflates. Also, front seat belts in newer cars are anchored with stiff stalks that are much farther forward than older models. That's safer for adults, but it could cause instability for a child seat during a crash. Such belts should be avoided.

Another seat belt system prone to parent error is any type of motorized shoulder harness that automatically shifts into position when the door is closed. In some cases, those systems require a special supplemental belt provided by the automaker.

Deborah Baer, president of the Maryland Child Passenger Safety Association, noted a trend of misuse in Baltimore, where she checks at least 200 cars a year.

"I'm finding approximately 85 to 90 percent misuse, easily," Baer said. "Most people don't understand how big of a problem this is. People don't see this as an issue because car seats aren't sexy like gun violence and gore."

Misunderstandings about car seats aren't limited to ordinary parents. Lt. Col. W. Gerald Massengill of the Virginia State Police said that when his department recently launched a program to educate troopers on child seats, many were surprised to learn how many mistakes can be made.

The federal government has been working for the last decade to solve incompatibility problems between the seven major types of seat belts and the numerous styles of child seats.

Howard S. Willson, a Chrysler vehicle safety engineer and chairman of the Society of Automotive Engineers' child restraint system task force, said U.S. automakers have spent the last five years trying to correct the problems.

Willson said vehicle designers and engineers trying to make cars safer for adults "were not paying any attention to the fact that changes they were making were detrimental to that compatibility."

Several automakers, including Chrysler, have built integrated child seats into some of their newer vehicles, such as minivans, taking the guesswork out of installation. But consumer response so far has been lukewarm because those seats can be costly and can be used for only two or three years, experts said.

Federal officials said the most promising solution is a system known as Isofix, a standardized design in which a built-in fastener on the child seat would snap directly into a device anchored to the vehicle frame. Isofix could be incorporated into all new cars and child seats around the world, proponents said. Just as consumers are assured electrical devices can be plugged safely into their home sockets, compatibility would be guaranteed for all cars and safety seats using Isofix.

But such a solution could be years away, Tombrello and others said, and current cars and child restraints will remain in use for decade or two.

In the meantime, child safety advocates are working hard to raise awareness.

"This is very much like the AIDS issue: You can be lucky a lot if you don't protect yourself, but the consequences can be terribly serious," Tombrello said. "Safety seats are there to protect our children as a form of immunization against a potentially fatal encounter. Most people don't realize it, but the tragedy of Dana is the tragedy of many."

The Hutchinsons have started the Drivers Appeal for National Awareness (DANA), a nonprofit foundation whose goals are to promote a simplified seat belt system and educate parents.

Most child seats require special modifications -- but the Hutchinsons were surprised to find that several police officers, auto dealers and other parents they contacted often knew little about how they could be performed. Some friends and acquaintances believed they had installed their child seats properly but were wrong, the Hutchinsons said.

"You shouldn't have to have any abnormally high level of intelligence to figure out how to put a car seat in," Bryan Hutchinson said. "It should be so simple, just completely simple, that if you're smart enough to get a driver's license, you should be able to figure it out."

Newer car safety belts and seat designs, engineered to be more comfortable for adults, can be deadly for children in safety seats if the belts are not modified. Different types and combinations of seat belts and child seats require different modifications. In some instances, seat belts can be modified with a simple metal locking clip; in others, car owners must have a free auxiliary belt or buckle installed. Below are some general guidelines for car safety seats.

The best references for proper installation and use are the child seat manufacturer's instructions, which come with the seat, and the safety section of your vehicle owner's guide.

GENERAL STEPS FOR POSITIONING A CHILD SEAT

* Read safety seat instructions and vehicle owner's guide for specific installation method.

* Properly secure child seat to car. If you have a belt that does not stay tight (a lap/shoulder belt with sliding latchplate, for example), use a metal locking clip, such as the one provided with all safety seats, to lock out the comfort feature allowing seat belts to move a bit.

* The metal locking clip should not be confused with the plastic harness retainer clip, which keeps the child-seat shoulder harness straps from slipping. The smaller the child is, the greater the chance he or she may be propelled from the child-safety seat in the event of a crash without the plastic harness retainer clip.

* Make sure the seat faces the proper direction: Child seats for infants must face rearward (so the child faces the car seat). Children under age 1 do not have the spinal development to survive a crash. With older children, the seat must face forward and be in an upright position.

* Once the seat is mounted, check for movement; if the seat can be moved significantly back and forth, it is not secured.

* Child seats should be checked every time they are used.

Securing child seat to car seat

1. To tighten a seat belt, press the child seat down into the car seat using full weight on a knee.

2. At the same time, take up slack of the lap belt. The child seat should stay in place when you try to push it from side to side.

POSSIBLE PROBLEMS IN SEAT INSTALLATION

* Never secure a child seat with an automatic belt. Belts mounted on doors never should be used.

* Most seat belt anchorage points are four to 10 inches forward from where they were mounted a decade ago, ensuring the belts rest across the pelvic area of an adult passenger. In the past, seat belts mounted farther back allowed them to rest across the abdomen of many passengers, causing serious injuries in accidents. The few inches of slack allowed by the new belt mounts is enough to permit a child seat to tip during a crash.

* New belts often are mounted on a stiff stalk or stitched to a latchplate, preventing child seats from being secured tightly. Use another belt in the car.

* Bucket or deeply contoured seats, especially those in the back seats of some smaller, sportier cars, prevent the child seat from resting properly.

* Rear-facing child safety seats should never be placed in the front passenger seat of a car equipped with a passenger-side air bag. When an air bag deploys, it can cause serious injury to an infant in a rear-facing safety seat.

OPTIMUM CHOICE

Specialists say the most foolproof type of seatbelt for securing a child seat is a manual lap belt such as the ones standard in most cars before the mid-1980s. Those can be found in the middle of the back seat of many cars.

WARNING TO PARENTS

Federal administrators have recalled several models of child seats because they fail to meet safety standards. To find out which seats are on the recall list, call the Auto Safety Hotline at 1-800-424-9393.

Text by Brian Mooar and Don Sena

SOURCES: American Academy of Pediatrics, National Highway Traffic Safelty Administration