A line of passengers wait to enter the security checkpoint before boarding their aircraft at Reagan National Airport in Washington
A line of passengers wait to enter the security checkpoint before boarding their aircraft at Reagan National Airport in Washington, April 25, 2013. Reuters

The Federal Aviation Administration (FAA) needs more air traffic controllers to address rising passenger demand, the chair of a U.S. Senate panel overseeing aviation issues said on Thursday, amid investigations into a series of recent runway incidents.

"We don't have enough pilots. We don't have enough maintenance people, and we don't have enough air traffic controllers," Democratic Senator Tammy Duckworth, who chairs the Senate Commerce aviation subcommittee, told Reuters.

A series of aviation close calls has sparked alarm and raised questions about the safety of the U.S. air system.

The FAA has been deciding how many air traffic controllers to employ by its budget "versus the actual need in terms of the traffic demands," Duckworth said.

The Transportation Department said last week it was seeking $117 million to hire 1,800 air traffic controllers next year, in addition to 1,500 being hired this year.

The National Air Traffic Controllers Association (NATCA), the union representing controllers, has pressed the FAA to boost staffing. Airlines and others have also called for more funding for air traffic controllers and have pointed to times when a lack of staff impacted flights.

"We have a staffing issue," NATCA President Rich Santa said at a FAA safety forum on Wednesday, noting there are 1,200 fewer certified air traffic controllers than a decade ago.

"It's time for us to accurately and adequately staff the facilities," he added.

Santa said a permanent fix was needed, along with a new staffing model, while Duckworth said the FAA and NATCA should do a "thorough study" and agree on the staffing levels required.

Senate Commerce Committee chair Maria Cantwell separately on Wednesday called on the FAA to take action on previous National Transportation Safety Board (NTSB) recommendations.

The FAA said late on Thursday that it would write rules to require cockpit voice recorders to capture 25 hours of information and establish a committee to explore how to make greater use of data gathered by airplanes, including expanded flight data monitoring.

After one of the recent runway incidents, the NTSB said the cockpit voice recordings in both planes were overwritten and not recovered because under current rules, the devices record only two hours. NTSB Chair Jennifer Homendy on Thursday called the FAA decision "a win for safety."

Cantwell said the United States should also require all airports with passenger airline services to have ground improvement safety systems to prevent runway incursions.

"We have to have the highest safety standards, and we have to have the investment in modern equipment that is going to give us those safety standards," Cantwell said.