(Another in an Inside Slant series on innovation in and around the NFL. For all Inside Slant posts, follow this link.)

It sounds so simple and smart. Buy one of them small flying thingamabobs, throw a camera on it, and use it to snap all new kinds of photos and video during practice.

Three NFL teams did just that during spring workouts -- by launching drones into the air above their practice fields to capture new and potentially edifying angles of their players' work. But not a single drone has flown -- at least not for football purposes -- in the first two weeks of training camp. Some teams have been delayed or deterred by FAA regulations, but based on recent conversations with multiple coaches, there remains a fair degree of skepticism about the current value and necessity of drone videos.

Advocates say a drone's ability to hover close to the line of scrimmage offers a unique vantage point for teaching and correcting mistakes. As of now, however, only a few NFL decision-makers agree.

"We looked at it hard, and for us it's just not there yet," Baltimore Ravens coach John Harbaugh said. "It's like the virtual reality technology that everyone's talking about. You start studying it, and it's incredibly cool. Then you start looking at applications. How can it help you? … I don't want to do anything that I don't know exactly what we're going to get out of it. To me, I feel like you're taking more away from what you're doing by chasing these things."

Harbaugh did add: "It's going to be a piece that can help one day. It won't change everything. It's not going to change the way the game is taught or anything. But it'll give another teaching tool."

Drones are nothing new in the worlds of government and technology, of course, but they gained momentum around the NFL this spring, when a company called Media Right introduced a new model known as Phantom 3. According to Media Right president Betsy Chapman, improved stability made this edition a better candidate to produce clear and detailed video. Soon, five NFL teams -- the Dallas Cowboys, Seattle Seahawks, Tennessee Titans, Oakland Raiders and New York Giants -- had placed orders. The St. Louis Rams ordered one this week, mostly for use in their digital/broadcast department, but with the option of football-related use in the future.

"In the past, these things have fallen into trees, and that turned off some teams," said Chapman, who runs the company out of Utah. "This [model] is sturdy and in control."

Users of the Phantom 3, which ranges from $999 for the basic model to $1,259 for the super–HD camera upgrade, can drive it with an iPhone or fly it indoors. Batteries cost around $129, and the machine can film for up to 15 minutes at a time.

The Cowboys were intrigued after visiting a spring practice at Southern Methodist University, where a drone was in use. SMU coach Chad Morris said he uses drone video to enhance quarterback development; watching a play from about 15 feet high and 10 yards behind the offense creates what Morris considers the ultimate vantage point for teaching.

Meanwhile, for red-zone work, Morris said drones give his coaches a wide-zone angle of the end zone. Ambitious teams can simulate quarterback movements inside a film room while replaying the action live.

"You can see the whole scope of the defense with a drone," Morris said. "It's the best way to do that."

The Cowboys brought Morris to one of their OTAs for more consultation and were one of three teams, along with the Giants and New England Patriots, who tested in the spring. (Details of the Patriots' use and origination of purchase are unclear.)

"This allows you to get a little closer, so you can coach better," Garrett told reporters. "You can see hand placement. You see where they have their feet, where they have their eyes. I think that's important. You can look at that and coach them better, being that much closer to the action."

The Cowboys are awaiting an FAA permit before using their drone in camp, as are the Titans. Giants spokesman Pat Hanlon said the team's decision not to use its drone was unrelated to FAA regulations but "strictly made an organizational/coaching decision at this point." Neither the Patriots nor Seahawks responded to questions on the topic. The FAA's full set of drone policies can be found on its website.

Pittsburgh Steelers coach Mike Tomlin, meanwhile, said he prefers to wait out new technology so "everyone else can knock all the kinks out before I get on board." Still, the Steelers couldn't use a drone at their training camp if they wanted to. Their practice fields at Saint Vincent College are about 3 miles from Arnold Palmer Regional Airport, which makes it a no-drone zone, according to team spokesman Burt Lauten.

The same is true for the Cleveland Browns, who practice 2.5 miles from Cleveland Hopkins Airport.

"You start worrying about air space," Brows coach Mike Pettine said. "That's one of the last things I want to have to worry about."

Pettine's comment aside, the league's current ambivalence isn't based solely on anti-technology fear. Rather than use drones this summer, the Ravens are experimenting with a MastRCam, a contraption that works like a periscope. A camera perched atop a pole shoots elevated video while a consultant watches and edits on the ground.

In Green Bay, the Packers decided their state-of-the-art practice facility gives them every angle they need.

"We're able to shoot from four locations," coach Mike McCarthy said. "Maybe it gives you something, but I don't feel it's necessary. To me, it's a bonus and not a necessity at all."

That sentiment could change as drone equipment improves over time. For now, however, the NFL is mostly a drone-free zone.

ESPN.com's Pat McManamon contributed to this report.