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FAA change icing regulations
5 August 2009

The U.S. Federal Aviation Administration (FAA) changed its certification standards for transport category airplanes to require either the automatic activation of ice protection systems or a method to tell pilots when they should be activated.
The new rule requires an effective way to ensure the ice protection system is activated at the proper time. The rule applies to new transport aircraft designs and significant changes to current designs that affect the safety of flight in icing conditions. There is no requirement to modify existing airplane designs, but the FAA is considering a similar rulemaking that would cover those designs.

Under the revised certification standards, new transport aircraft designs must have one of three methods to detect icing and to activate the airframe ice protection system:

* An ice detection system that automatically activates or alerts pilots to turn on the ice protection system;
* A definition of visual signs of ice buildup on a specified surface (e.g., wings) combined with an advisory system that alerts the pilots to activate the ice protection system; or
* Identification of temperature and moisture conditions conducive to airframe icing that would tip off pilots to activate the ice protection system.

The standards further require that after initial activation, the ice protection system must operate continuously, automatically turn on and off, or alert the pilots when the system should be cycled. (FAA)