Expect the legal fireworks to fly if an aerial advertising company follows through with its intent to tow banners across Oahu skies this Independence Day weekend over the strong objections of the city and the Outdoor Circle.

Aerial advertisers have twice challenged Honolulu’s aerial sign law in recent years and lost.

But Aerial Banners North intends to use its single-engine Piper Pawnee to fly either a large U.S. flag or "most likely some kind of public service announcement" above Oahu in the coming days, and has Federal Aviation Administration approval to do so, said company attorney Michael J. McAllister.

Noting that it already flew Old Glory over Oahu during the Memorial Day weekend and may be doing so again over the Fourth of July, McAllister said "it is inappropriate for the city to say, ‘You can’t do that.’"

Ian Gregor, FAA Pacific Region public affairs manager, confirmed to the Honolulu Star-Advertiser by email that Aerial Banners North obtained a waiver from the agency allowing it to conduct banner-towing operations. That waiver, McGregor said, applies to both the mainland and Hawaii.

Gregor referred other "local legal issues" to McAllister.

Honolulu Mayor Kirk Caldwell, in response, fired off a letter to Gregor demanding revocation of the company’s waiver, as well as clarification of FAA’s position on the matter. Caldwell pointed out that the city’s aerial advertising prohibition ordinance has been upheld twice by the 9th U.S. Circuit Court of Appeals — against the Center for Bio-Ethical Reform in 2006 and Skysign International Inc. in 2002.

In the 2006 case, Caldwell said, the FAA stated that the agency does not pre-empt the city law.

"Our review of your current guidelines for issuance of a certificate of waiver or authorization for aircraft banner tow operations indicates that such guidelines have not changed since the court decisions on this issue,"Caldwell wrote.

Caldwell, in a news release, said "what this company is doing is illegal and we’re going to put a stop to it."He urged the public to call 911 if it sees an illegal aerial advertising banner over Oahu skies.

City ordinances say violating the prohibition could result in penalties of up to $500 per violation, a maximum of three months in jail or both.

The Outdoor Circle, the organization largely credited for preserving Hawaii’s strict billboard prohibitions, issued its own cease-and-desist demand against Aerial Banners North.

Marti Townsend, Outdoor Circle executive director, said towing aerial banners is illegal under both state and city laws.

FAA rules say specifically that any waiver "does not waive any state law or local ordinance,"Townsend said. While recent changes to the format of FAA’s certificate of waiver forms suggest the agency is not responsible for enforcing Hawaii’s advertising laws, Townsend told McAllister the changes "do not alter your client’s responsibility to follow all of the laws in the state of Hawaii."

Townsend said her organization will take "appropriate legal action" against the company if it continues its aerial advertising activities.

McAllister said the company has flown its aerial banner advertising throughout the U.S. In April; it specifically asked that Hawaii be included in its "geographic area of operations."

U.S. law governing federal airspace states clearly that only the federal government has "exclusive sovereignty of airspace of the United States,"McAllister said.

Addressing the point Townsend raised, McAllister said changes made to the FAA’s banner-towing manual deleted language stating that federal laws do not supercede local or state ordinances. Therefore, he said, "it is clear … the FAA now completely pre-empts the field of banner towing, and the local Honolulu ordinance is pre-empted by federal law."

While Aerial Banners North itself has never challenged municipal ordinances against aerial signage, other companies have and won, he said.

McAllister said that in Hawaii to date, the company has flown banners displaying only the American flag and the phrase "aerialbanners.com."

He said he did not know whether the company has agreed to do any commercial advertising for a fee from an outside business.