HOUSTON -- The Houston Police Department has stepped up its campaign to alleviate safety concerns over the unmanned aircraft it plans to use for patrols over the city.

KPRC Local 2 Investigates reported that area pilots were kept in the dark, including two planes that flew dangerously close to the secret test flight that was captured by Local 2 Investigates' hidden cameras last month.

HPD issued a new statement, asserting that safety was the top priority at the test site, and will continue to be the priority as future tests are conducted.

Phil Boyer, with the national Aircraft Owners and Pilots Association said, "Our level of concern is extremely high on more of these secret tests."

He said Houston-area pilots were kept in the dark about the HPD test flight of the drone aircraft. Local 2 Investigates found two different planes flying dangerously close to the drone as it circled over Waller County last month.

"Rest assured, the tests are just the tip of the iceberg," Boyer said.

Mayor Bill White told Local 2 he still had concerns about the drones. "Oh sure," he said. "They (have) got to be safe. We can't interfere with air traffic."

HPD issued a statement in response to the Mayor's comments and other concerns in this week's broadcast.

The statement spells out that radar and HPD helicopter pilots on the ground were both keeping an eye on the nearby air traffic to avoid a mid-air collision.

The statement also claimed that nearby aircraft operations were warned of the test in advance, something that KPRC Local 2 Investigates could not confirm after speaking with numerous local pilots and airport managers.

The statement also said that Houston air traffic controllers were tracking the drone during the entire test flight. However, KPRC Local 2's helicopter was also being tracked by Houston air traffic control, and the KPRC pilot was never given any indication of the drone test over aircraft frequencies, even though controllers knew the station's helicopter was in the area. KPRC employees also monitored those frequencies for warnings to other aircraft, but no warning or mention was ever heard on those frequencies.

The HPD statement said that FAA representatives were on site and they praised HPD for the test.

Houston Police Chief Harold Hurtt also included the new statement about safety on his http://hpdchief.blogspot.com.