...Both the FCC and the Federal Aviation Administration must approve the use of cell phones in airline cabins. If the FCC rules in favor of a change, the FAA still isn't likely to seriously begin grappling with the question until 2006, pending results of its own studies.

For its part, the FAA has banned cell phone use aboard commercial flights because of concern that the transmissions could interfere with aircraft navigational equipment. The agency has commissioned a report by the nonprofit RTCA Inc., formerly the Radio Technical Commission for Aeronautics, to examine the issue. So far, the FAA has not proved conclusively that cell phones interfere with navigation. But the agency has long preferred to err on the side of caution.

"The problem is there is no data or evidence that cell phones do or do not cause a problem," said FAA spokeswoman Laura Brown.

In its review, the FCC will address whether cell phones used on airliners are a problem for communications on the ground. An FCC study in 2000 found that dropped or blocked calls on the ground increased because passengers overhead were talking on their cell phones. Cellular signals coming from high altitudes are spread across several base stations, interfering with callers on the ground who are using the same frequencies.

...Airlines, aircraft manufacturers such as Boeing and telecommunication companies such as Verizon have lobbied hard on the issue. Several carriers, recognizing that business travelers crave to remain connected, have won approval from the FAA and FCC to test how cell phones affect their own aircraft systems. American Airlines and Qualcomm Inc. conducted tests in the summer.