Letters obtained by the Associated Press say air traffic controllers at a Lexington Airport in Kentucky complained to federal officials earlier this year about short-staffing in the tower.
The letters were sent in April 2005, to Kentucky's two U.S. senators.
In the letters a control tower worker said the overnight shift was not always fully staffed and management was to blame.
Federal guidelines say two workers were supposed to be working when Comair flight 5191 crashed after takeoff on Aug. 27, 2006, but only one was present. The air controllers' union leader, Faron Collins, wrote the letters to Sens. Jim Bunning and Mitch Mcconnell.
Another controller wrote to the FAA's accountability board last year complaining about a hostile work environment in the tower.
Meanwhile, a plane scheduled to land at Bluegrass Airport on Sept. 11, 2006, stayed on the ground in Cincinnati, Ohio, when the lights were out on the main runway in Lexington, Ky.
The outage was caused by a power problem and workers had to manually switch to a backup regulator. It took about 40 minutes to fix the problem and get the runway lights back on. No other flights were affected by the outage.