WASHINGTON -- In the wake of Tuesday's four catastrophic hijackings, the Federal Aviation Administration has called for a series of new security measures, measures that many observers feel do not address the fundamental problems of the U.S. air travel system.

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Among the fixes: a ban on all knives in carry-ons, an end to curbside check-in. Also, only ticketed passengers will be allowed through security. The new rules miss one of the main marks, according to a former FAA inspector general.

"What we need is nationally coordinated federal law enforcement oversight of airports because we are only as safe as our weakest link," aviation safety expert, Mary Schiavo, said.

The main line of security at airports will still be the screeners who staff the metal detectors and X-ray machines. There are some 20,000 of these staff members at U.S. airports and their record over the years has been anything but spectacular.

"This system is not a good one -- it's like a Swiss cheese," airline consultant Darryl Jenkins said. "We all know this. I don't think any of us would congratulate ourselves or anyone else who is involved in airport security with the job we have done over the last 10 years."

Long before Tuesday's hijackings, the problems were apparent. When the General Accounting Office sent undercover operatives carrying bogus law enforcement credentials to two major airports last year, none of them was stopped by security, CNN reported.

And the FAA's own tests last year found that European screeners spotted twice as many mock weapons as U.S. screeners under virtually the same conditions.

According to Jenkins and other consultants, the lax security is a case of "you-get-what-you-pay-for." The airlines are responsible for staffing the security checkpoints, but they contract the work out to security companies.

"The airlines are the ones that put the bids out, and the airlines are the ones that make the decision, and I can tell you that routinely they take the lowest bidder," says Tom Balanoff of the Service Employees Union.

About 100 different companies provide security at U.S. airports. The screeners they hire aren't required to have any specialized experience. In fact, one help wanted ad running online the week before the terror attacks touted that walk-ins were welcome.

At many airports, the GAO found that security screeners often make less than fast-food workers in the terminal.

"It's very low-paying and leads nowhere. So really, you have no incentives to get there. You have no places to move from that job. So we see very low-quality personnel who turn over very rapidly," Jenkins said.

According to the GAO, St Louis' airport had a 400 percent turnover of security screeners in the year ending April 1999; Atlanta had 375 percent.

"In Logan Airport, the turnover figure is 200 percent a year, and you can contrast that to particularly airports in western Europe. In Belgium, the turnover rate is 5 percent. At Manchester airport, which provides probably double the wages at Logan, and health insurance, the turnover rate is 1 percent," Balanoff says.

Turnover is just one problem. The largest provider of airport security in the United States -- Argenbright -- is on probation with the FAA.

Last year, the FAA found that some of its security screeners at the Philadelphia airport had criminal records, including convictions for kidnapping, drug dealing, and aggravated assault, CNN reported.

Argenbright provides security at two of the airports where hijackers boarded planes on Tuesday morning -- Dulles and Newark. After the hijackings, Argenbright had no comment, referring all inquiries to the airlines.

According to CNN, the FAA is about to announce new certification standards for companies that provide airport security. And there's now talk in Congress about having the federal government take over airport security.

As flights returned to the skies for the first time on Thursday, Argenbright screeners and others around the country were back on the job, on the lookout for dangerous items.

But even as screeners at the Phoenix airport collected numerous knives from carry-on luggage, two Northwest Airlines crew members who were carrying a corkscrew and a pocketknife passed through without detection, CNN reported.

For some, it was just another reminder that the current security screening system needs to change fundamentally.

"I don't know if one airline right now feels comfortable with having a contract system," said Jenkins. "I have predicted in the next year that we will see massive changes. The changes were coming, and change is always slow, and now change will come at warp speed."