Towering wind turbines off Cape Cod will not pose a hazard to planes, the Federal Aviation Administration ruled Wednesday, clearing what is believed to be the final federal regulatory hurdle for the controversial 130-turbine project.

The FAA released a short statement to the Globe that said the agency “completed an aeronautical study and has determined that the proposed construction of the 130 wind turbines, individually and as a group, has no effect on aeronautical operations.’’

The FAA’s decision is the latest in a series of positive rulings by federal and state agencies on the controversial project in Nantucket Sound. While there have been many declarations of final approval by Cape Wind and its supporters during the 11-year effort to build the ­nation’s first offshore wind farm, a review by the Globe ­indicates that Cape Wind has all the major permits it needs.


Although Cape Wind executives have not announced financ­ing for the project, which is expected to cost more than $2.5 billion, the company has commissioned engineering studies and promised to begin construction next year.

Opponents have long ­expressed concerns that the 440-foot turbines pose a danger to aircraft, but the issue rose in prominence during the last two years as other approvals were awarded for the project. The FAA’s previous approval for Cape Wind was overturned last year by the US Court of Appeals for the District of Columbia, which said the agency failed to adequately ­review how difficult it could be for pilots to navigate over 25 square miles of wind turbines.

The court ordered the agency to review its findings. In the meantime, Cape Wind asked the FAA for a new decision, which was announced Wednesday.

The FAA has reexamined the project against a backdrop of a congressional investigation into the aviation agency’s review of Cape Wind, as well as e-mails from FAA officials that were ­obtained by the main oppo­sition group that alluded to the extreme political sensitivity of the project.


“It’s unfortunate the FAA once again ignored very real safety concerns and ignored the previous court decision to revoke Cape Wind’s aviation safety permit,” said Audra Parker, president of the Alliance to Protect Nantucket Sound, the project’s main opposition group. She pledged to appeal the FAA’s decision and said four lawsuits remain against the project.

The FAA examines structures to determine if they are so high that they would obstruct pilots or whether they could inter­fere with radar needed to locate aircraft. The determination released Wednesday found that Cape Wind will not ­obstruct pilots because the turbines are below a 500-foot threshold. An upgrade to the radar in the area, as part of a national effort, should ensure there is no radar interference, but Cape Wind must set aside $15 million to fix any problems.

Decisions by the FAA that a project presents no hazard are good for only 18 months. If construction does not start within that time frame, Cape Wind will have to go before the agency again, as it has several times earlier because no-hazard decisions expired.

“Cape Wind is once again pleased to have received FAA approval,’’ said Mark Rodgers, a spokesman for Cape Wind. “This is the fourth determination of no hazard during the FAA’s 10-year review of Cape Wind, which began in the [George W.] Bush administration.”

Cape Wind has overcome years of environmental review and political opposition, includ­ing that by the late Senator Edward M. Kennedy, whose home overlooked Nantucket Sound. More recently, two Wampanoag Native American tribes have said that the turbines would disturb spiritual sun greetings and ancient burial grounds now covered by the sea. A movie was even made about the project called “Cape Spin! An American Power Struggle.”


Interior Secretary Ken ­Salazar approved the wind farm in 2010, and the project gained new traction earlier this year when a merger between NStar and Northeast Utilities included a promise for NStar to purchase almost 30 percent of Cape Wind’s output, supposedly giving Cape Wind enough promised sales to secure financing. The company had previously negotiated with National Grid to buy 50 percent of its electricity.

“This decision is consistent with the other FAA decisions; overall, this project will not be a threat to birds and planes,” said Jack Clarke, director of public policy and government relations for the Massachusetts Audubon Society, which has supported Cape Wind.

Beth Daley can be reached at bdaley@globe.com.