FAA spokeswoman Lynn Tierney said the agency is simply doing its job. "We are aware and sympathetic... but the role is clear, it's a regulator's role," Tierney said.

Tierney was referring to the safety order issued on the Boeing Co. MD-80 aircraft that recently have been grounded. The FAA ordered visual inspections of certain wire bundles on those planes after reports of shorted wires, evidence of worn-down power cables and fuel system reviews conducted by the manufacturer. Transportation Department Inspector General Calvin L. Scovel III on Thursday repeated his findings about the FAA's inspection office responsible for Southwest Airlines having "developed an overly collaborative relationship" with the carrier.

"The FAA needs to do more than just trust these airlines," Senator Amy Klobuchar, D-Minn., said to conclude the hearing. "We have some good ideas on the table, but we need to go beyond the letter-writing back and forth and into action."