WASHINGTON -- Broadcasters filed an emergency objection to a plan introduced by the Federal Communications Commission chairman this week, asking the agency to slow down efforts to open up vacant TV airwaves for unlicensed use.

Station owners and the four television networks filed an emergency request Friday afternoon, asking the FCC to hold off on its plan to vote on rules to allow the use of those unused TV airwaves – also known as "white spaces" – until everyone has a chance to comment on the findings of a recent...