The U.S. Federal Communications Commission has stopped proceedings to consider allowing cell phone use during flights.
The FCC cites insufficient technical information on whether the use of cellular phones onboard aircraft may cause harmful interference to terrestrial networks, as the reason to stop the proceedings. In December 2004, the FCC adopted a Notice of Proposed Rulemaking (NPRM) to examine the existing rule that requires cellular phones to be turned off once an aircraft leaves the ground in order to avoid interfering with cellular network systems on the ground.
Federal Aviation Administration (FAA) regulations also restrict the use of cellular phones and other portable electronic devices (PEDs) onboard aircraft to ensure against interference with the aircraft’s navigation and communication systems.
More details on the FCC site.