The weekend before Warner Bros. studios planned to make television history, the weather was not cooperating. In normally sunny California, there had been days of rain. Luckily, mother nature played ball. On December 15, 2014 the production team of "The Mentalist" was able to fly a drone on set for the first time in Motion Picture Association history.

In September 2014, the Federal Aviation Administration gave permission to a handful of drone companies to begin operating in Hollywood. The industry lauded it as a huge step forward. Drones are a cheaper and easier way to get aerial footage than, say, a helicopter. Hollywood has been using them to film memorable movie sequences for years (remember the flying car scene in “Harry Potter and the Chamber of Secrets”?). The only catch was, because of a ban on the use of unmanned aerial vehicles (UAS) in the U.S., production companies had to go to Europe, Canada or Asia to shoot those scenes.

Related: FAA approves drone use in Hollywood

Now a small number of companies are allowed to operate in the U.S. including AerialMob, the company operating the drone camera for “The Mentalist” scene. CEO Treggon Owens says his company has made a point of working with the FAA on things like safety rules.

“[The September decision] means we can work legally and most importantly it means that the studio types, people like this group, will legally allow us to operate. Nobody on the studio level and above would ever allow drones to operate on our sets without drones being legal,” he said.

What Owens is hinting at here is a major grey industry for drones in this country. He estimates that thousands of flights take place each day. There are a number of industries clamoring to legally be able to use drones. Take farmers, for instance, who hope to use the unmanned vehicles to regularly survey hard-to-reach areas of their fields in order to detect problems early and improve harvests. Owens explains further:

A grey market drone is doing everything from doing real estate shots today to construction management to power line inspection. Those things are happening on a day-to-day basis across the nation. There’s also a heck of a lot of video being generated and used. I mean any car commercial you see on TV there’s generally going to be an aerial and I’m going to guarantee you, since there’s only been eight legal jobs done, none of those car commercials were done in a legal framework but every single car commercial you see on TV has this.

It's not just Hollywood. Dozens of industries have lobbied the FAA to use drones. In fact, the FAA’s very first exemption to the UAS flight ban went to oil giant BP (BP) who used a drone to monitor remote oilfields in Alaska.