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Wednesday, 02 December, 2009

FAA Removes Rules Allowing For "Polished Frost"


December 2, 2009

What’s at Issue

The Federal Aviation Administration (FAA) has issued a final rule affecting 14 CFR Part 91 subpart F, Part 125 and Part 135 that removes the allowance for “polished frost” on critical aircraft surfaces during takeoff.

Why It’s Important

This final rule will require critical surfaces on aircraft used by affected operators to be clear of frozen contamination prior to take-off.  This rule also provides clarification of required equipment for flight into known or forecast icing conditions.

Major Provisions

This final rule affects the following aircraft/operators:

  1. Part 91 subpart F - Large and Turbine-Powered Multi-engine Airplanes and Fractional Ownership Program Aircraft
  2. Part 125 – Airplanes having a seating capacity of 20 or more passengers or a maximum payload capacity of 6,000 pounds or more
  3. Part 135 – Commuter and on-demand operators

Sections 91.527(a), 125.221(a) and 135.227(a) were revised to remove the reference for operations with “polished frost.”  Pilots must ensure that the following surfaces are clear of frost, ice or snow prior to take off:

    1. Windscreen
    2. Stabilizing or control surfaces
    3. Powerplant installation
    4. Airspeed, altimeter, rate of climb, or flight attitude instrument system
    5. Wing surfaces
      1. Frost may be accumulated under the wing fuel tank area if authorized by the FAA

Sections 91.257(b), 125.221(c) and 135.227(c) were amended to clarify previously confusing wording.  The revised regulations state that pilots may not fly under IFR into known or forecast light or moderate icing conditions or under VFR into known light or moderate icing conditions, unless one of the following conditions is met:

  1. The aircraft has functioning de-icing or anti-icing equipment meeting regulatory requirements
  2. The airplane has ice protection provisions that meet section 34 of Special Federal Aviation Regulation No. 23
  3. The airplane meets transport category airplane type certification provisions

NATA Position
NATA submitted comments that generally supported these changes.  The adherence of any contaminants to aircraft surfaces is known to have negative aerodynamic consequences.  Also, according to the FAA, the prior exception could essentially only be used if the aircraft manufacturer provided guidance on polishing frost, which none offer.  The changes to 135.227(c) are welcome clarification for the industry as that regulation has been the subject of numerous misunderstandings among operators and inspectors alike.

The regulatory changes made in the Final Rule are effective on February 1, 2010.  A copy of the final rule is available here.

View in report in PDF format.

Staff Contact:   Mike France
Director of Regulatory Affairs

For general press inquiries, contact Shannon Chambers at 703-298-1347 or

The National Air Transportation Association (NATA) has been the voice of aviation business for over 75 years. Representing nearly 2,300 aviation businesses, NATA’s member companies provide a broad range of services to general aviation, the airlines and the military and NATA serves as the public policy group representing the interests of aviation businesses before Congress and the federal agencies.