HOUSTON -- Local 2 Investigates broke the story on a secret test by Houston police. Now Houston's mayor is applying the brakes on HPD's controversial plan to fly unmanned drones. Tonight, many who saw our story here and across the country are raising new concerns. Video you haven't seen from that secret test shows why.

Local 2 investigative reporter Stephen Dean has the new drone danger concerns.

A Houston-area pilot had no idea how close he is to danger. He's in one of two airplanes we saw, close to HPD's secret test of unmanned aircraft last month over Waller County.

"This is a recipe for disaster," said Phil Boyer, head of the Aircraft Owners and Pilots Association in Washington, D.C.

Boyer says pilots are worried coast to coast.

"Well, as soon as the story aired on your channel, my e-mails started ticking," Boyer said. "Numerous e-mails."

Local 2 Investigates uncovered a secret test flight last month. HPD now says its study of unmanned aircraft will help set policy for police departments nationwide.

"The FAA has seen an increasing interest in the use of unmanned aircraft by law enforcement agencies across the country," said Capt. Tom Runyan of HPD's Traffic and Accident Division.

It's a new worry for a Houston pilot, proudly watching his teenage son land their plane at Hooks Airport.

"He's (his son) going to have to see and avoid these things and I don't want to hit one," says Bill Wilson, a Houston pilot. "I sure don't want any of my family to hit them either."

Wilson strapped in and took us on a flight to show us all the dangers he has to watch out for anyway. If police are quickly and secretly launching drones like they did for the test, he says it spells trouble in the air.

"It's the chance of a mid-air collision," Wilson said. "If they launch them up because they have what they consider an emergency, there's no way to alert pilots once they get in the air."

During the test, HPD lied to our Local 2 Investigates pilot, telling us the airspace was restricted. They claimed we'd get in trouble with the FAA if we didn't leave. However, there was no airspace restriction and no way for pilots in the area to even know police had launched the test.

"Rest assured, the tests are just the tip of the iceberg." Boyer said. "The FAA has denied allowing organizations, like ours, that can communicate with pilots to know about these tests going on, like the one in Houston, until they actually occur."

That's one of the reasons Mayor Bill White is now telling Houston police to slow down.

"Whether a drone would be appropriate and safe, we don't know yet," White said.

When HPD quickly held a news conference because we exposed their secret, they claimed done patrols could start as early as June. Now, the mayor says no.

"We've got to have conversations and feedback from citizens and hold hearings and come up with criteria," White said. "I want to be clear, too, that I'm not telling HPD not to pursue this."

Pilots like Wilson are hoping this means no more rush to get drones up in the air with him and his son. He agrees with the mayor that it needs more study than HPD seemed ready to give it.

"If you hide things that are very, very important to your own safety, then it just becomes very unsafe, very quickly." said Wilson.

Mayor White says he has no timetable on when public hearings would take place, but he says he wants to hear concerns about privacy and flying dangers when drones would be over populated areas. He says he's in favor of the new technology for catching killers and other serious police work, but only if it's thoroughly studied.

Houston police say they'll be testing a different sort of drone in the coming months. It's a hovering aircraft that can take pictures from above.