The skies may be getting too friendly, according to data obtained by USA Today. Plane are getting too close together and errors by air traffic controllers are on the rise.

• Controller errors climbed from 746 in fiscal 1997 to 878 in fiscal 1998 -- an 18 percent increase.

• The errors per million flights handled by controllers climbed from 4.8 to 5.5.

• Federal Aviation Administration figures for the first quarter of fiscal 1999 -- October through December of 1998 -- also show that errors are ahead of last year's pace.

• For traffic flying above 29,000 feet, planes must be separated by five miles horizontally -- but may pass closer than that if they are at least 2,000 feet apart vertically.

Experts report that separation distances shrink as planes near airports.

FAA officials are relying on two systems now under development to increase safety in coming years. One allows controllers and pilots to communicate via an e-mail-like system. The other uses computers to give controllers more warning when planes are headed toward each other.

An official of the National Air Traffic Controllers' Association says he thinks improved controller morale will reduce errors.

Source: Alan Levin, "Planes Get Closer in Midair as Traffic Control Errors Rise," USA Today, February 24, 1999.