8 August 2007
Docket No. FAA-2005-22840
FAA

This detailed 15-page rule becomes effective 9 October 2007. It culminates a proposed rule issued 4 November 2005 which generated extensive comment from the industry.. The final rule establishes a set of requirements for measuring airplane performance and handling characteristics in icing conditions and defines ice accretion in terms of size, shape, location and texture of ice encountered.

The rule also is intended to harmonize FAA regulations with those anticipated from the European Aviation Safety Agency. In addition, this final rule addresses a number of concerns expressed in its comments by the National Transportation Safety Board (NTSB), which has investigated a number of fatal crashes and non-fatal incidents involving icing.

Comments from the NTSB, submitted 2 February 2006, were extensive, covering standards for certifying airplanes for flight in icing conditions. The FAA claims in its ruling that it has accommodated the NTSB’s concerns:

In its letter, the NTSB said:

“The Safety Board has been concerned for many years about the inadequacy of the existing certification regulations for flight in icing conditions, which have not required manufacturers to demonstrate an airplane’s flight handling, stall characteristics, minimum airspeeds, and stall margins under a sufficiently realistic range of adverse ice accretions.”

In its final rule, the FAA declares:

“This amendment requires applicants to investigate the susceptibility of airplanes to ice-contaminated tailplane stall during airworthiness certification. …”

“This amendment partially addresses [testing in all conditions in which the airplane is certificated to operate] by revising the certification standards to ensure that transport category airplanes are properly tested for the critical icing defined in appendix C of part 25. We are considering future rulemaking action to address icing conditions beyond those covered in appendix C. …”

“Although neither an aural stall warning or stick shaker is required under this amendment, all recently certificated transport category airplanes have used either a stick shaker or an aural warning to warn the pilot of an impending stall.”

We have asked the NTSB for comment as to whether this final rule is fully responsive to its concerns. Our reading is that it is not. The FAA has deferred action on supercooled liquid droplets (SLD) – a major concern of the NTSB – to future rulemaking action. Nor does the rule appear responsive to the NTSB’s call for a means of alerting the pilot to impending stall. The fact that all recently certificated airplanes were equipped with an aural warning and/or stickshaker is not the issue. This final rule addresses future airplane designs.