The US Federal Aviation Administration (FAA) has proposed a $1.9 million fine on a commercial unmanned air systems (UAS) operator, the largest penalty yet assessed in the agency’s growing crackdown on the unmanned industry.

The FAA accuses Chicago-based SkyPan International of operating 65 unauthorized commercial UAS flights over a nearly three-year period ending in December 2014. Forty-three of those flights occurred in Class B airspace in New York City, within 5mi of LaGuardia Airport, the FAA says.

A SkyPan International employee who answered at a phone call at the company’s offices declined to comment until they had a chance to review the FAA’s proposed fine.

“It kind of dropped on us, so we’re just trying to get our ducks in order at this point,” says SkyPan production coordinator Karl Brewick.

SkyPan has 30 days to officially respond to the FAA’s proposed fine. The company’s options include paying the fine, negotiating different terms or challenging the FAA’s case for the fine in court, according to an FAA spokeswoman.

The company and the FAA have already been battling in court for more than a year. Court documents show that the FAA sued SkyPan International in US District Court in Illinois last year, seeking a court order to force the company to comply with a subpoena. SkyPan had argued that the FAA did not have jurisdiction to subpoena the company for information about alleged airspace violations.

SkyPan has operated for 27 years as an urban aerial photography sevice. It first developed a camera platform for manned helicopters. Since 2007, it has advertised aerial photography services using the SkyPan Remotely Piloted Vehicle (RPV), which court documents and regulatory filings identified as a two-bladed helicopter weighing less than 9kg (20b).

In court documents, the FAA claims that SkyPan received more than $132,000 from a New York realtor to take aerial pictures of a vacant lot for sale on Park Avenue. The FAA believed that SkyPan violated several airspace restrictions, including operating the helicopter at night without lights, operating a helicopter within 1,000ft of an obstruction and operating in Class B airspace without permission from air traffic control, court documents say.

The legal dispute over SkyPan’s alleged activities between 2012 and 2014 did not stop the FAA from approving the company’s application to operate UAVs commercially earlier this year.

In April, the FAA granted SkyPan’s request for an exemption to operate an unmanned helicopter for aerial photography services.

The proposed fine will not void or change the exemption that allows SkyPan to operate UAVs commercially now, an FAA spokeswoman says.