National Transportation Safety Board Chairman Ellen Engleman Conners' two-year term expired Sunday. The rules governing the board don't allow her to continue in that role unless the president renominates her - and then she must be confirmed by the Senate, a process that could take months.
Vice Chairman Mark Rosenker is acting chairman. But that's only for two weeks because his term expires April 2. The board's rules allow the vice chairman to serve as acting chairman without Senate confirmation.
It's not unusual for the White House to be slow in announcing presidential nominations.
Among the most controversial issues during Connors' term was the investigation into the crash of American Airlines Flight 587, which lost its tail on Nov. 12, 2001, and plunged into a Queens, N.Y., neighborhood, killing 265 people.
The safety board, which only has the power to investigate and recommend safety improvements, found the airline and the manufacturer, Airbus Industrie, were both partially to blame.
Bitter public disagreements between the airline and Airbus Industrie in the months leading up to the ruling were unusual for an NTSB investigation. Conners later said that both parties had lobbied the board inappropriately.
The NTSB went through the same leadership uncertainty in January 2003, when the Bush White House waited until just before Acting Chairman Carol Carmody's term was about to expire before naming a replacement.
