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8 May 2008 FAA
FR Doc E8-10246 Docket No. FAA-2007-29281
Notice of Proposed Rulemaking (NPRM), Removal of Regulations Allowing for Polished Frost on Wings of Airplanes
The FAA is proposing to remove provisions in its regulations that allow flights of private airplanes with “polished frost” (i.e., frost polished to make it smooth) on the wings.
By this change, the regulators have decided, after almost 50 years, that it’s no longer safe for private airplanes (Part 91) and cargo aircraft (Part 135) to fly with polished frost on their wings. Since 1960, the FAA has allowed some planes – not commercial passenger planes – to fly with ice on the wings as long as the ice was smooth. That left it up to the operators to clean off the wings themselves and decide whether it was safe to fly.
The regulatory action comes after several fatal crashes of business aircraft that were attributed to ice on the wings and an increase in the use of corporate and fractional-ownership jets in the last decade.
A January 2002 crash in Birmingham, England that killed two business executives and three pilots illustrated the dangers of ice on aircraft. British investigators pointed out that the plane had been flying under the “polished frost” regulation and they recommended that the FAA delete all reference to polished frost.
In 2004 and 2005, fatal crashes in Colorado, attributed to ice on the wings, provided further impetus for change.
In addition, the FAA said there are at least 11 known incidents in which aircraft with polished frost did not generate sufficient lift and crashed after takeoff.
Commercial aircraft operate under rules that call for a “clean wing” before take-off and de-ice treatment at the airport before departure under certain weather conditions.
While the old rule said pilots could take off “with frost adhering to wings or stabilizing or control surfaces if that frost had been polished to make it smooth,” the consensus now is against any ice on the wing. The FAA concluded that any ice on the wing poses a number of problems. As indicated in the NPRM:
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A contaminated wing’s maximum lift may be reduced by 30% or more.
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The angle of attack for maximum lift may be reduced by several degrees.
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Drag may increase significantly.
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The airplane’s handling qualities and performance may change unexpectedly from that of the uncontaminated aircraft.
The FAA discovered numerous inventive, though sometimes disastrous, ways to clean ice, snow and frost off the surfaces of aircraft. For example, running a rope against the wing surface to remove frost, brushing it off by hand or with a broom, using a paper towel, of even using a credit card as a scraper.
Under the NPRM, operators would have four ways to comply with the proposed rule:
1) Wing covers
2) Waiting for the frost to melt.
3) Storing the aircraft in a heated hangar.
4) De-icing the wing surface.
Of these choices, the FAA believes wing covers “are the lowest cost alternative” According to the FAA, wing covers meet the test of cost-benefit, costing the industry about $164,000 over the ten year period 2009 to 2018, while benefits (presumably accidents avoided) over this same period amount to $460,000. It is not entirely clear how these costs and benefits were calculated, as the cost of a single fatal accident can run to the millions of dollars.
The National Transportation Safety Board (NTSB) has been asking the FAA since the 1990s to revise its rules on icing conditions and the certification of airplanes to fly in those conditions. The NTSB has maintained, based on past investigations, that the wings need to be free of ice, frost or snow.
The FAA now concludes:
“Complete removal of frost from critical surfaces to achieve uncontaminated surface smoothness is necessary to ensure acceptable airplane airworthiness. If all wing surfaces, other than those under the wing in the area of the fuel tank, and control surfaces are not uniformly smooth upon take off, the FAA believes an unsafe condition exists.”
Comments on the NPRM are due 6 August 2008. | 
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