DENVER -- The head of the Federal Aviation Administration wants to know why United Airlines has allowed employees who have pled guilty to felony crimes to remain on the job.

A 7NEWS Investigation uncovered felons on United Airlines' payroll. 7NEWS Investigator John Ferrugia shared the FAA's response to the report.

FAA officials say the nation's airlines will be directed this week to begin checking the backgrounds of every employee with a badge that allows them access to high security areas in and around aircraft.

The FAA wants to keep those with serious criminal histories from so-called "sterile" areas.

Currently, most airlines have no idea whether airline employees -- who work in and around aircraft with checked baggage and mail that is transported by air -- have criminal histories.

That's because, as 7NEWS has shown with United Airlines, there are no systems in place to check employees' criminal records after they are on the job.

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In the case of one United employee who was convicted of arson for burning down his girlfriends house, United has known about his record but decided to keep him on the job.

"That's one of those that we want to look at a little more carefully to see exactly what the circumstances were," FAA administrator Jane Garvey said.

Garvey says the new regulation requiring background checks for all badged employees is designed to make sure that felons do not have access to secure areas.

"As a matter of fact, we have had discussions with United to take a look at what the circumstances are. And I know that would be of concern to the airline as well. You want to make sure you are doing it right," Garvey said.

It is cases like this one, Garvey says, that make it clear that the existing regulation on background checks needs to be tightened.

"It is not sufficient. So we've got to plug every hole we can," Garvey said.

Garvey says there will be audits to make sure the airlines are, in fact, conducting the new, 10-year criminal background checks.

She says this is only a first step -- in the future, she expects there will be additional rules to insure re-checks on a regular schedule.

So, the loopholes pointed out in 7NEWS' investigation are slowly being closed.