The head of security at Washington Dulles International Airport (search) was placed on administrative leave because of his arrest on drunken driving charges as the airport was on a heightened state of alert early New Year's Day for terrorist activity, the Transportation Security Administration said Friday.

Charles Brady, acting federal security director at Dulles, was pulled over Thursday morning, hours after a British Airways jetliner was detained at the airport because of intelligence information.

Airport spokeswoman Tara Hamilton said a Metropolitan Washington Airports Authority (search) police officer took Brady into custody after he saw him driving erratically. It was unclear whether Brady was supposed to have been on duty when he was arrested.

The Transportation Security Administration named Adm. James Schear acting federal security director at Dulles during an investigation of Brady's arrest, agency spokesman Darrin Kayser said.

Brady was arrested when the nation was at a heightened alert level because of terrorism concerns that also disrupted more than a half-dozen New Year's holiday flights, including three British Airways flights between Dulles and London.

Intelligence indicated Al Qaeda operatives had been showing interest in using commercial planes to stage an attack and pointed to possible strikes on cities that included Washington. The capital was protected by surface-to-air missile systems during the holidays.

Jennifer Marty, TSA spokeswoman, said Brady and other federal security directors at the nation's airports were notified on New Year's Eve that they should plan to stay at work until after midnight because the agency was conducting emergency drills. Brady was pulled over at 1 a.m. EST and taken to the Fairfax County Detention Center, where he spent the night before being released Thursday afternoon.

The federal security director position is relatively new. Not long after the Sept. 11, 2001, terror attacks, the Transportation Security Administration (search) quickly hired federal security directors to oversee security at 429 commercial airports.

Rafi Ron, a Washington-based security consultant and the former security director for the Israeli Airport Authority, said he considered Brady's arrest a personal tragedy rather than a widespread systemic problem.

"I think it's a single incident," Ron said. Most federal security directors are former Army generals or Coast Guard and Navy admirals, he said.

"I guess he was under a lot of pressure," Ron said. "Whatever the stress is, when you've been chosen for that job, you should be able to handle that type of pressure."

Efforts to reach Brady were unsuccessful.

On Dec. 12, the federal security director at Philadelphia was put on paid leave for reasons that the TSA would not disclose.

Local news reports said James Golden was suspended because of practices that included hiring and promoting his son-in-law and hiring a former exotic dancer to supervise screeners. Golden categorically denied the allegations.