“We remain a long way from creating a single European airspace,” the commissioner, Siim Kallas, said in prepared remarks that he plans to deliver Thursday at a conference of regulators, air traffic management bodies and airline executives in Limassol, Cyprus. “There are some signs of change, but overall progress is too slow, and too limited. We need to think of other solutions and apply them quickly.”

Quickly, in this case, means meeting an initial Dec. 4 deadline that the E.U. has set. By that time, all European Union members are expected to complete agreements to merge their various national airspaces into nine “functional airspace blocs.” And by early next year, the countries will be obliged to demonstrate clear progress on reducing costs in the control system and increasing air traffic.

Improvements cannot come quickly enough in the view of David McMillan, director general of Eurocontrol, an agency in Brussels that is responsible for coordinating the flow of air traffic in what are now 39 jurisdictions. “This is a huge change-management project,” he said, “and there is no single, clear leader to drive it.”

The European Union has sought for more than a decade to unify the crazy quilt of national air traffic control systems. The aim is to reduce or eliminate differences in procedures that officials say are responsible for about 5 billion euros ($6.5 billion) in unnecessary costs each year — not to mention millions of tons in wasted fuel and added carbon emissions from inefficient routes.

This year was meant to be a crucial one for pushing through the master plan, known as the Single European Sky. Legislation passed by the European Parliament in 2009, for example, envisioned the creation of the nine airspace blocs, which would each adopt common operating procedures, technologies and fee structures — a first step toward full alignment the law envisioned by 2020.