The United States missed a year-end deadline for publishing new rules on remote-control aircraft, delaying an eagerly awaited step toward using drones in everything from farming to package delivery.
Businesses have been clamoring for rules to allow commercial drone flights, fearing the United States is falling behind other countries in developing a multibillion-dollar industry.
The Federal Aviation Administration turned a draft of the rules - the first major overhaul of the regulations - over to the White House on Oct. 23, and had said it expected them to be published in 2014.
But the White House Office of Management and Budget had not released the draft by Wednesday. The office has 90 days to review proposed regulations, during which time analysts craft a cost-benefit analysis and meet with affected parties. The time frame often is extended.
Once published, the draft proposal will be subject to public comment, and it is likely to take at least a year to come into effect, according to legal and policy experts.
"We are continuing to work with our administration colleagues to finish the rule," the FAA said on Wednesday. "Our goal is to get the proposal right."
The rules deal with difficult issues such as potential licensing of drone pilots and aircraft and flight safety, according to industry sources.
They also must address the explosive growth of casual fliers with little knowledge of safety guidelines used by model-aircraft enthusiasts, industry experts say. The proliferation of inexpensive drones has led to more dangerous close calls with jetliners and crowds, the FAA says.
The rules also may deal with the ability of state and local authorities to regulate drones. The FAA controls the U.S. airspace, but numerous states and cities have also passed drone laws. The FAA may include a "pre-emption clause" in the draft rules to assert its precedence over other laws.
"The FAA does not want a patchwork of regulations that deal with operation of model aircraft," said Mark Dombroff, a partner at the law firm of McKenna Long & Aldridge in McLean, Virginia.
Dombroff led a group including Textron Inc, Rockwell Collins Inc and the Motion Picture Association of America that recently met with the FAA to press for pre-emption. While that probably won't be in the first draft, it likely will emerge through public comments, he said.