The Federal Aviation Administration (FAA) will require scheduled airlines to either retrofit their existing fleet with ice-detection equipment or make sure the ice protection system activates at the proper time.

For aircraft with an ice-detection system, the FAA proposes that the system alert the crew each time they should activate the ice protection system. The system would either turn on automatically or pilots would manually activate it.

For aircraft without ice-detection equipment, the crew would activate the protection system based on cues listed in their airplane’s flight manual during climb and descent, and at the first sign of icing when at cruising altitude.

"This is the latest action in our aggressive 15-year effort to address the safety of flight in icing conditions," said FAA Administrator Randy Babbitt. "We want to make sure all classes of aircraft in scheduled service remain safe when they encounter icing."

The FAA estimates the rule would cost operators about $5.5 million to implement. Operators would have two years after the final rule is effective to make these changes.

The proposed rule would apply only to in-service aircraft with a takeoff weight less than 60,000 pounds, because most larger airplanes already have equipment that meets the requirements.

The FAA says smaller planes are more susceptible to problems caused by undetected icing or late activation of the ice protection system.

The rule technically affects only an estimated 1,866 airplanes since all turbojet airliners and many turboprops covered under the rule already have equipment that satisfies the requirements. And the FAA believes others will be retired before the projected compliance date in 2012.

In August 2009, the FAA changed its certification standards for new transport category airplane designs to require either the automatic activation of ice protection systems or a method to tell pilots when they should be activated.

Since 1994, the FAA has issued more than 100 airworthiness directives to address icing safety issues on more than 50 specific aircraft types. These orders cover safety issues ranging from crew operating procedures in the icing environment to direct design changes.

The FAA has also required changes to airplane flight manuals and other operating documents to address icing safety, and issued bulletins and alerts to operators emphasizing icing safety issues.

As part of the proposed rulemaking, the FAA is seeking public comment on whether the rule should be broadened to apply to larger planes.

The NPRM responds to the crash of a Circuit City Stores business jet in 2005. The Cessna Citation 560 jet crashed as it approached Pueblo, CO, killing all eight people on board, because pilots let ice build up on the wings and didn’t maintain proper airspeed, the National Transportation Safety Board said in 2007. The NTSB recommended a rule requiring that de-icing systems be activated as soon as planes enter conditions conducive to ice buildup.