The government approved new ice-removing equipment Monday for use on ATR regional airliners.
Restrictions on flying the twin-engine propeller planes in freezing drizzle or freezing rain will remain in effect, however, said Dan Salvano, a Federal Aviation Administration specialist in aircraft certification.
Use of the planes in icy weather was sharply restricted late last year after 68 people were killed in the crash of an American Eagle plane Oct. 31 in Roselawn, Ind. The most severe of the restrictions have since been eased.
The FAA said installation will begin immediately for the new de-icing boots, which double the area covered by current de-icing equipment on the ATR-42 and ATR-72. The deadline to complete installation on the estimated 175 ATRs in service in the United States is June 1.
Although the National Transportation Safety Board has not yet formally determined the cause of the Roselawn accident, ice accumulation on the wings is suspected. The plane had been circling in icy conditions.
Salvano said that once the new boots are installed the agency will consider whether any of the remaining flight restrictions imposed on the ATRs can be eased. These include a ban on flight in freezing drizzle or freezing rain; requirements that pilots monitor ice accumulation; prohibiting the use of flaps in icing conditions; banning use of the autopilot in icing conditions, and requiring that flaps not be retracted if they are extended when the plane is in freezing rain or drizzle.