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Safety Recommendation Details

Safety Recommendation A-07-016
Details
Synopsis: On February 16, 2005, about 0913 mountain standard time,1 a Cessna Citation 560, N500AT, operated by Martinair, Inc., for Circuit City Stores, Inc.,2 crashed about 4 nautical miles east of Pueblo Memorial Airport (PUB), Pueblo, Colorado, while on an instrument landing system (ILS) approach to runway 26R. The two pilots and six passengers on board were killed, and the airplane was destroyed by impact forces and postcrash fire. The flight was operating under the provisions of 14 Code of Federal Regulations (CFR) Part 91 on an instrument flight rules flight plan. Instrument meteorological conditions (IMC) prevailed at the time of the accident.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: When the revised icing certification standards (recommended in Safety Recommendations A-96-54 and A-98-92) and criteria are complete, review the icing certification of pneumatic deice boot-equipped airplanes that are currently certificated for operation in icing conditions and perform additional testing and take action as required to ensure that these airplanes fulfill the requirements of the revised icing certification standards. (A-07-16) (This safety recommendation supersedes Safety Recommendation A-98-100)
Original recommendation transmittal letter: PDF
Overall Status: Closed - Unacceptable Action
Mode: Aviation
Location: Pueblo, CO, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA05MA037
Accident Reports: Crash During Approach to Landing, Circuit City Stores, Inc., Cessna Citation 560, N500AT
Report #: AAR-07-02
Accident Date: 2/16/2005
Issue Date: 2/27/2007
Date Closed: 12/3/2013
Addressee(s) and Addressee Status: FAA (Closed - Unacceptable Action)
Keyword(s): Icing,Weather

Safety Recommendation History
From: NTSB
To: FAA
Date: 12/3/2013
Response: On June 6, 2011, the FAA stated its position that “known safety concerns for in-service airplanes related to the Board’s safety recommendation A-07-16 have been addressed” by a series of actions described in its letter. As a result, the FAA believed that (1) there would be little benefit to retroactively applying new design regulations to existing airplane designs and (2) such a requirement would not be justified. The FAA therefore considered its actions in response to this recommendation to be complete. On September 12, 2011, we replied that we disagreed with the FAA and pointed out that this recommendation specifies that an evaluation of in-service airplanes should be conducted after the revised icing certification standards recommended in Safety Recommendations A-96-54 and A-98-92 are complete. On June 29, 2010, the FAA published its long-awaited notice of proposed rulemaking (NPRM), “Airplane and Engine Certification Requirements in Supercooled Large Drop [SLD], Mixed Phase, and Ice Crystal Icing Conditions,” which proposed the standards recommended in Safety Recommendations A-96-54 and A-98-92 and which will be applicable to new aircraft. We did not believe that the actions described in the FAA’s June 6, 2011, letter adequately addressed the ability of currently certificated aircraft to safely fly in SLD conditions. In our September 12, 2011, letter, we described our participation in an accident investigation then being conducted by the Junta de Investigaciones de Accidentes de Aviación Civil (JIAAC) of Argentina. On May 18, 2011, a Sol Lineas Aéreas Saab 340A was en route from Neuquén, Argentina, to Comodoro Rivadavia, Argentina, when the flight crew declared an emergency and the airplane subsequently disappeared from radar. The aircraft was later discovered, crashed, about 35 kilometers from Los Menucos, Argentina. It had been operating in icing conditions, and early investigative findings suggested that it might have encountered SLD conditions, possibly resulting in the loss of control and crash. We believed this was precisely the type of situation that Safety Recommendation A-07-16 is meant to address: an airplane currently certificated for flight in icing conditions (such as the Saab 340) that has not demonstrated the ability to safely operate in SLD conditions. Because this investigation was in progress when we wrote our letter, detailed information was not yet publicly available. Although the FAA stated that it regarded its action in response to Safety Recommendation A-07-16 to be complete and it planned no further action, we believed that, before we closed this recommendation, the FAA should review the results of the JIAAC investigation, once these results became available. This recommendation is now 6 1/2 years old, and it superseded Safety Recommendation A-98-100, issued 15 years ago. The NTSB believes that actions taken in response to safety recommendations should usually be completed within 5 years of the recommendation’s issuance. Although we believe the JIAAC investigation will provide information supporting this recommendation, the investigation has not yet been completed, nor does it appear that the report will be available soon. We continue to urge the FAA to examine this investigation closely when it is completed, but we also believe it unreasonable to further delay closing the recommendation. Accordingly, because the FAA plans no further action in response to Safety Recommendation A-07-16 and because we do not believe that the FAA has effectively corrected the unsafe conditions, the recommendation is classified CLOSED—UNACCEPTABLE ACTION.

From: NTSB
To: FAA
Date: 9/12/2011
Response: The NTSB disagrees with the FAA that “known safety concerns for in-service airplanes related to the Board’s safety recommendation A-07-16 have been addressed” by the series of actions described in the FAA’s letter. This recommendation specifies that an evaluation of in-service airplanes should be conducted after the revised icing certification standards recommended in Safety Recommendations A-96-54 and A-98-92 are complete. On June 29, 2010, the FAA published its long-awaited notice of proposed rulemaking (NPRM), “Airplane and Engine Certification Requirements in Supercooled Large Drop [SLD], Mixed Phase, and Ice Crystal Icing Conditions.” This NPRM proposed the standards recommended in Safety Recommendations A-96-54 and A-98-92. The actions described in the FAA’s June 6, 2011, letter do not adequately address the ability of an aircraft to safely fly in SLD conditions. The NTSB further disagrees with the FAA that there would be little benefit to retroactively applying the new design regulations to existing airplane designs, or that such a requirement would not be justified. The NTSB is currently participating in an investigation being conducted by the Junta de Investigaciones de Accidentes de Aviación Civil (JIAAC) of Argentina. On May 18, 2011, a Sol Lineas Aéreas Saab 340A was en route from Neuquén, Argentina, to Comodoro Rivadavia, Argentina, when the flight crew declared an emergency, followed by the airplane disappearing from radar. The aircraft was later discovered, crashed, about 35 kilometers from Los Menucos, Argentina. It had been operating in icing conditions, and early investigative findings suggest that it may have encountered SLD conditions it could not handle, and that this had resulted in the loss of control and crash. We believe this is precisely the type of situation that Safety Recommendation A-07-16 is meant to address: an airplane currently certificated for flight in icing conditions (such as the Saab 340) that is not able to safely handle SLD conditions. This investigation is currently ongoing, and detailed information is not yet publicly available. Although the FAA stated that it regards its action in response to Safety Recommendation A-07-16 to be complete and plans no further action, we believe that before we close this recommendation, the FAA should review the results of the JIAAC investigation, once these results become available. Because the NTSB disagrees that the FAA has effectively corrected the unsafe conditions as intended by Safety Recommendation A-07-16, pending completion of the recommended action, this recommendation remains classified OPEN—UNACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 6/6/2011
Response: CC# 201100234: - From J. Randolph Babbitt, Administrator: The Federal Aviation Administration (FAA) has taken the following major actions related to icing to specifically address this safety recommendation in order to ensure safe operation of existing airplanes equipped with pneumatic deicing boots: • Issued more than 25 airworthiness directives (AD) for Title 14, Code of Federal Regulations (14 CFR) parts 23 and 25 airplanes equipped with de-icing boots requiring activation at the first sign of ice accretions anywhere on the aircraft. We also require cycling of the boots in the auton1atic mode, if available, or manually operating to minimize the ice accretions on the airframe. An example of an AD for activation of deicing boots at the first sign of icing is AD 99-19-10, which was applicable to Aerospatiale Model ATR-42 and ATR-72 series airplanes and became effective on December 27, 1999; • Issued more than 40 severe icing ADs for 14 CFR parts 23 and 25 airplanes equipped with pneun1atic deicing boots and unpowered ailerons. The ADs provide the flight crew with visual cues to determine when the airplane has encountered severe icing conditions that exceed the capabilities of the airplane~ s ice protection equipment. The ADs also require specific procedures in the airplane flight manual for exiting the severe icing environment. An example of an AD for detecting and exiting severe icing conditions is AD 96-09-24, which was applicable to Embraer Model EMB-120 series airplanes and became effective on June 11, 1996; • Conducted a roll control force evaluation that addressed 14 CFR parts 23 and 25 airplanes equipped with pneun1atic deicing boots and unpowered ailerons that are used in regularly scheduled revenue passenger service in the United States. The evaluation included a sin1ulated ice shape installed aft of the deicing boots and forward of the ailerons. The simulated ice shape represented possible ice formation in supercooled large drop icing conditions. We found all airplanes to have acceptable roll control forces should a ridge of ice form aft of deicing boots and forward of the ailerons; and • Conducted an ice contaminated tailplane stall evaluation of existing airplanes with unpowered flight control systen1s (of which many are equipped with pneumatic deicing boots) operating under 14 CFR part 121 or part 135 operating rules. The FAA mandated changes to improve tailplane stall margins for airplanes found to be susceptible. We provided a list of ADs in the FAA response to this safety recommendation dated September 22, 2009. The actions discussed above apply to in-service airplanes. Proposed rulemaking activities will apply to future designs. In the interim, for airplane certification projects initiated after the ADs became effective, the FAA has imposed the intent of the ADs or required airplane evaluations to ensure safe operations through issue papers for each new certification project. The issue paper process provides a means to identify and resolve significant technical, regulatory, and administrative issues occurring during the certification process. The FAA considers whether or not a new regulation should apply to in-service airplanes. For activation of ice protection equipment, the FAA revised the design standards and has also proposed new operational regulations that would apply to airplanes most affected by flight in icing conditions regardless of when they were certified. Current status for that rulen1aking activity is provided in response to safety recommendations A-07-14 and A-07-15. The FAA maintains that known safety concerns for in-service airplanes related to the Board~ s safety re¢on1n1endation A-07-16 have been addressed as discussed above. As a result~ we believe there would be little benefit to retroactively applying the new design regulations to existing airplane designs, and such a requirement would not be justified. I believe that the FAA has effectively corrected the unsafe conditions as intended by this safety recommendation and consider our actions con1plete.

From: NTSB
To: FAA
Date: 8/27/2010
Response: Notation 6486F: The National Transportation Safety Board (NTSB) has reviewed the Federal Aviation Administration (FAA) Notice of Proposed Rulemaking (NPRM), “Airplane and Engine Certification Requirements in Supercooled Large Drop, Mixed Phase, and Ice Crystal Icing Conditions,” published at 75 Federal Register 37311 on June 29, 2010. The FAA proposes to amend the airworthiness standards applicable to certain transport-category airplanes certificated for flight in icing conditions and the icing airworthiness standards applicable to certain aircraft engines. The NTSB initially became concerned with supercooled large droplet (SLD) conditions, including freezing rain and freezing drizzle, in the early 1980s and issued a report on September 9, 1981, titled Aircraft Icing Avoidance and Protection. This report identified the need for the FAA to review and revise the icing criteria in 14 Code of Federal Regulations (CFR) Part 25, Appendix C, to include freezing rain and for that reason issued Safety Recommendation A-81-116. On October 31, 1994, American Eagle flight 4184, ATR-72, crashed at Roselawn, Indiana. The investigation found that freezing drizzle icing conditions led to the creation of an ice ridge aft of the deice boots on the upper surface of the wing. This ridge caused the airflow over the ailerons to separate, which resulted in an uncommanded roll of the airplane. Based on its findings, the NTSB issued Safety Recommendation A-96-54, which superseded recommendation A-81-116 and requested the following of the FAA: Revise the icing criteria published in 14 Code of Federal Regulations (CFR), Parts 23 and 25, in light of both recent research into aircraft ice accretion under varying conditions of liquid water content, drop size distribution, and temperature, and recent developments in both the design and use of aircraft. Also, expand the Appendix C icing certification envelope to include freezing drizzle/freezing rain and mixed water/ice crystal conditions, as necessary. This recommendation is one of the oldest recommendations on the NTSB’s Most Wanted List of Transportation Safety Improvements and is currently classified “Open—Unacceptable Response.” The status of this recommendation highlights the NTSB’s ongoing concern that current icing certification requirements do not ensure that airplanes are tested in the most severe icing conditions, as defined in the environmental icing envelope contained in Appendix C. Accordingly, the NTSB has repeatedly stressed the need to consider the full range of icing conditions in which an airplane is authorized to operate. Additionally, the NTSB has voiced its concern that flight crews must be provided a means to recognize when an aircraft encounters conditions beyond those for which the aircraft has a demonstrated safe flight capability. In this regard, and as a result of its investigation of the Roselawn accident, the NTSB issued Safety Recommendation A-96-56 to the FAA: Revise the icing certification testing regulation to ensure that airplanes are properly tested for all conditions in which they are authorized to operate, or are otherwise shown to be capable of safe flight into such conditions. If safe operations cannot be demonstrated by the manufacturer, operational limitations should be imposed to prohibit flight in such conditions and flightcrews should be provided with the means to positively determine when they are in icing conditions that exceed the limits for aircraft certification. This recommendation is also on the NTSB’s Most Wanted List of Transportation Safety Improvements and is currently classified “Open—Unacceptable Response.” Since the issuance of these recommendations, the NTSB has investigated several accidents and incidents that have involved SLD conditions, including the 1997 Comair 3272 Embraer (EMB) 120 accident, which occurred in Monroe, Michigan; the 2001 Comair 5054 EMB-120 stall and loss of control event, which resulted in the flight diverting to West Palm Beach, Florida; the 2005 Circuit City Cessna 560 accident, which occurred on approach to Pueblo, Colorado; and the 2006 American Eagle flight 3008 Saab 340B in-flight upset and loss of control over Santa Maria, California. These accidents and incidents again highlighted the hazards of operating in SLD conditions, which were not required to be considered at the time of the original icing certification of these airplanes. As a result of these investigations, the NTSB stressed the need to include SLD conditions in the icing certification standards for all airplanes certificated for flight in icing conditions. These accidents and incidents demonstrated that SLD conditions can be more hazardous than those considered during current icing certification, that SLD conditions can cause ice accretions more aerodynamically detrimental than those that develop while flying within the Part 25, Appendix C, envelope, and that airplanes need to be evaluated over the full range of icing conditions for which they are authorized to operate, including a range of SLD conditions. Given the accident history described above, the NTSB is pleased that the NPRM proposes to add Section 25.1420, which would require evaluating the operation of airplanes in the SLD environment, and Appendix O, Part I, to Part 25, which expands the certification icing environment to include freezing rain and freezing drizzle by using four separate droplet size distributions and includes droplet sizes greater than 1,000 microns in one of the distributions. Additionally, the NTSB is pleased to see the inclusion of Appendix O, Part II, which states the following: The most critical ice accretion in terms of airplane performance and handling qualities for each flight phase must be used to show compliance with the applicable airplane performance and handling qualities requirements for icing conditions contained in subpart B of this part. Applicants must demonstrate that the full range of atmospheric icing conditions specified in part I of this appendix have been considered, including drop diameter distributions, liquid water content, and temperature appropriate to the flight conditions. The NTSB 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, including SLD. Additionally, the regulations have not required airplanes to be tested with the thin, rough ice that can accrete on protected surfaces prior to the activation of ice protection systems or between activation cycles of the ice protection systems, especially in larger water droplet environments. The proposed rule addresses these problems with the addition of Section 25.1420 by requiring that airplane operations in icing conditions do not diminish the safety margins, handling qualities, and performance of the airplane and that the airplane should be as safe to operate in icing as in non-icing conditions. In addition, the proposed addition of Part 25, Appendix O, Part II, will provide an additional margin of safety for these airplanes when operating in icing conditions by defining the ice accretions and revising the performance and handling requirements for flight in icing conditions that must be satisfied to certify an airplane for operation in Appendix O icing conditions. These requirements include, for example, requirements for takeoff performance, stall warning, and landing climb. The NTSB has stated in past NPRM comments that the full range of atmospheric conditions must be considered when evaluating icing certification, and inclusion of this provision in Part II of Appendix O will ensure that all of these conditions are addressed during the icing certification process. The NTSB has also reviewed the FAA’s proposed changes for 14 CFR Section 33.68 “Induction System Icing,” Section 33.77 “Foreign Object Ingestion – Ice,” and the addition of Appendix D, Icing Envelope Limits. The NTSB investigated three incidents of dual-engine flameouts in Hawker Beechcraft (previously identified as Raytheon) Beechjet 400A airplanes that occurred between July 12, 2004, and June 14, 2006. In one of these incidents, the pilots had to accomplish a dead stick landing after they were unable to restart either of the engines. The NTSB’s investigations of these incidents showed that all three airplanes were operating in areas near convective weather activity with high altitude ice crystals, and the flight crews had retarded the power levers. The manufacturer of the engines installed on the Beechjet conducted a study that showed the possibility that high altitude ice crystals would partially melt due to the temperature rise in the air across the fan and ice could then adhere and refreeze on the compressor inlet stator in the engine’s core, causing the engine to flame out. Hawker-Beechcraft developed procedures for the Beechjet 400A airplane prescribing activation of the engine anti-icing system when operating within specified horizontal and vertical distances from convective weather activity to prevent ice from forming inside the engine. The FAA mandated incorporation of the revised procedures into the airplane flight manual with an airworthiness directive (AD). To date, there have been no further reports of dual-engine flameouts in Beechjet 400A airplanes. While pleased with the FAA’s issuance of the AD, the NTSB has been concerned that the FAA’s action addressed Beechjet 400A aircraft only without allowing for future engine designs that could be susceptible to the deleterious effects of high altitude ice crystals. The NTSB agrees with the FAA’s proposed changes in 14 CFR 33.68 and 33.77. In particular, the NTSB supports inclusion of proposed 14 CFR 33.68(e) and the Appendix D Inflight Icing Envelope, which address mixed phase and ice crystal conditions to ensure that future engine designs are not susceptible to high altitude ice crystals. The NTSB also agrees with the proposed turbine engine icing certification requirement, which would include the icing conditions of Appendixes C and O of Part 25, and the mixed phase and ice crystal icing envelope of Appendix D of Part 33. Despite the improvements noted in this letter, the NTSB is disappointed with the proposed rule and believes that it should be expanded to include all aircraft regardless of maximum takeoff weight (MTOW) or flight control design and that the requirements should apply to both newly manufactured and currently certificated aircraft under Part 25 (transport-category airplanes) and Part 23 (normal, utility, aerobatic, and commuter airplanes). If the requirements are not expanded to include currently certificated airplanes, the NTSB believes that flight crews need additional means to positively determine when they are in icing conditions that exceed the limits of the aircraft. As described in the NPRM, the proposed rule will require that only transport-category airplanes with an MTOW of less than 60,000 pounds, or those with reversible flight controls, meet the safety standards in the expanded certification icing environment defined by Part 25 Appendix O. As a result, the proposed rule excludes numerous aircraft models that would benefit from the new requirements. The NTSB does not agree with this position, nor does the Aviation Rulemaking Advisory Committee (ARAC) Ice Protection Harmonization Working Group (IPHWG), as noted in the NPRM: The IPHWG majority … did not accept the exclusion of airplanes with the three aforementioned design features because one cannot predict with confidence that the past service experience of airplanes with these specific design features will be applicable to future designs. The IPHWG majority recommended applying the new SLD airplane certification requirements proposed in the new § 25.1420 to all future transport category airplane type designs. The IPHWG majority opposed limiting the applicability of the rule based on airplane gross weight, in part, because the ratio of wing and control surface sizes to airplane weight varies between airplane designs. Therefore, airplane takeoff weight is not a consistent indicator of lifting and control surface size or chord, which are the important parameters affecting sensitivity to a given ice accretion. In addition to its reservations concerning weight limits, the NTSB believes that this rule should apply to all airplanes regardless of their flight control system design and that the effects of SLD accretions should be considered for all aircraft with either reversible or irreversible flight control systems. However, flight control system anomalies while operating in an SLD environment comprise only one aspect of the SLD threat. Another insidious feature of ice accreted while operating in SLD conditions is that the ice may significantly reduce the angle of attack required for aerodynamic stall to occur, so much so that stall can occur prior to the stall warning, as demonstrated in the Pueblo Cessna 560 accident and five ATR-42 incidents preceding the Roselawn accident. This problem is particularly critical when the stall protection system and warning margins have been determined using Part 25 Appendix C ice accretions, but the aircraft encounters SLD icing conditions, thereby causing much greater reductions of maximum lift than the system was designed for. The NTSB therefore believes that the requirements in the proposed rule should retroactively apply to all aircraft, regardless of their MTOW or the design of their flight control systems. An additional shortcoming in the proposed rule is its restriction to airplanes certificated under Part 25. As recommended in A-96-54, the NTSB believes that SLD should be considered for both Part 25 and Part 23 airplanes, which include several commuter type airplanes regularly used in passenger service. The NTSB has noted in past comments that these types of smaller aircraft typically operate at lower altitudes and are therefore more likely to encounter SLD conditions than the larger, turbine-engine aircraft certificated in Part 25, which spend less of their time operating at lower altitudes. Finally, because SLD is an atmospheric condition that can create dangerous flight conditions for the current fleet of aircraft, the NTSB believes that the proposed rule should be expanded beyond newly certificated airplanes to include all deice boot-equipped airplanes currently in service that are certificated for flight in icing conditions. The NTSB has noted that deice boot-equipped airplanes typically operate at lower altitudes more conducive to SLD encounters and must be properly tested for all icing conditions in which they are authorized to operate. The NTSB believes that the FAA should apply icing certification standards contained in this NPRM, including the provisions of Appendix O, to all deice boot-equipped airplanes currently certificated for flight in icing conditions. The NTSB stated this concern 12 years ago in Safety Recommendation A-98-100, issued to the FAA as a result of the Comair EMB-120 accident in Monroe, Michigan: When the revised icing certification standards and criteria are complete, review the icing certification of all turbopropeller-driven airplanes that are currently certificated for operation in icing conditions and perform additional testing and take action as required to ensure that these airplanes fulfill the requirements of the revised icing certification standards. This recommendation was classified “Closed?Unacceptable Action/Superseded” when Safety Recommendation A-07-16 was issued to the FAA on February 27, 2007, as a result of the February 16, 2005, Pueblo Circuit City accident. This new recommendation again stressed that revised certification requirements should apply to currently certificated deice boot-equipped aircraft, as well as new aircraft: When the revised icing certification standards (recommended in Safety Recommendations A-96-54 and A-98-92) and criteria are complete, review the icing certification of pneumatic deice boot-equipped airplanes that are currently certificated for operation in icing conditions and perform additional testing and take action as required to ensure that these airplanes fulfill the requirements of the revised icing certification standards. (A-07-16) (Open?Unacceptable Response) To summarize, the NTSB supports the Part 25 regulatory revisions proposed in this NPRM and believes that the new rule will be an essential step in improving the safety of flight for airplanes operating in icing conditions. However, the NTSB continues to believe that the proposed rule should be expanded to include all aircraft regardless of MTOW or flight control design and that the requirements should apply to both newly manufactured and currently certificated aircraft under both Parts 25 and 23. The NTSB appreciates the opportunity to comment on this NPRM.

From: NTSB
To: FAA
Date: 4/27/2010
Response: The NTSB disagrees with the FAA’s conclusion that a formal evaluation of all airplanes equipped with pneumatic deicing boots to ensure that these aircraft comply with all icing certification criteria for new aircraft is not warranted. This recommendation specifically indicates that the evaluation of in-service airplanes should be conducted after the revised icing certification standards recommended in Safety Recommendations A-96-54 and A-98-92 are complete. The FAA has previously advised the NTSB that it believed the standards were sufficiently developed to make this determination, and the NTSB agreed with the FAA. However, it appears there has been a misunderstanding. The NTSB believed that the FAA would apply the standards recommended by the ARAC in December 2005 in response to Safety Recommendation A-96-54. Based on the FAA’s current letter, the FAA does not seem to believe that these standards must be used to meet the intent of Safety Recommendation A-07-16. Because the FAA has not yet issued the NPRM for these standards, let alone adopted a final rule mandating them, the FAA’s conclusion that a formal evaluation is not needed does not constitute an acceptable response to this recommendation. Accordingly, at its February 18, 2010, meeting, the Board voted to retain the classification OPEN -- UNACCEPTABLE RESPONSE for Safety Recommendation A-07-16.

From: FAA
To: NTSB
Date: 9/22/2009
Response: Letter Mail Controlled 10/5/2009 3:57:02 PM MC# 2090620: - From J. Randolph Babbitt, Administrator: The Board's letter dated September 10, 2008, reiterated their May 10, 2006, position, that to meet the intent of Safety Recommendation A-98-100 (now A-07-16), the FAA must formally evaluate all airplanes equipped with pneumatic deicing boots that are currently certificated for operation in icing conditions to ensure that these aircraft comply with all current icing certification criteria for new aircraft. We have taken the following major actions to ensure the safe operation of existing airplanes that are equipped with pneumatic deicing boots: Issued over 25 Airworthiness Directives (Ads for parts 23 and 25 airplanes requiring: Activation of the deicing boots at the first sign of ice accretions anywhere on the aircraft, and Cycling the boots in the automatic mode, if available, or manually operating to minimize the ice accretions on the airframe. Issued over 40 severe icing Ads for parts 23 and 25 airplanes equipped with pneumatic deicing boots and unpowered ailerons. The Ads provide the flight crew with visual cues to determine when the airplane has encountered severe icing conditions that exceed the capabilities of the airplane's ice protection equipment. The Ads also require the flight crew to exit the severe icing conditions; Conducted a roll control force evaluation that addressed parts 23 and 25 airplanes used in regularly scheduled revenue passenger service in the United States and equipped with pneumatic deicing boots and unpowered ailerons. All airplanes were found to have acceptable roll control forces should a ridge of ice form aft of deicing boots and forward of the ailerons; and Conducted an ice contaminated tailplane stall evaluation of existing airplanes with unpowered flight control systems (of which many are equipped with pneumatic deicing boots) operating under parts 121 or 135 operating rules. The FAA mandated changes to improve tailplane stall margins for airplanes found to be susceptible. These changes were mandated through the following Ads We believe the above actions adequately address the safe operation of existing aircraft equipped with pneumatic deicing boots. Therefore, a formal evaluation of all airplanes equipped with pneumatic deicing boots to ensure that these aircraft comply with all current icing certification criteria for new aircraft is not warranted, The remaining ongoing icing rulemaking projects for existing airplanes are provided here for information only as they address other safety recommendations but are not required for completion of A-07-16. These actions include the issuance of Part 121 Activation of Ice Protection System and Part 121 Exiting Icing rules. The Part 121 Activation of Ice Protection System rule will ensure timely activation of the ice protection system. The rule will apply to all airplanes operating under part 121, which have a maximum certificated takeoff weight less than 60,000 pounds. The FAA reports details of the Part 121 Activation of Ice Protection proposed rule to the Board through A-07-14. The Part 121 Exiting Icing rule will require flight crews of airplanes equipped with unpowered roll controls and that have a maximum certificated takeoff weight less than 60,000 pounds, to exit conditions that are conducive to the formation of ice accretion aft of the protected areas, unless the airplane is certificated for flight in SLD. We plan to initiate a Part 121 Exiting Icing proposed rule early in 2010. The FAA reports details of the Part 121 Exiting Icing proposed rule to the Board through A-96-56. I believe that the FAA has effectively addressed this safety recommendation, and I consider our actions complete.

From: NTSB
To: FAA
Date: 9/10/2008
Response: This safety recommendation supersedes Safety Recommendation A-98-100 by including all pneumatic deice boot equipped airplanes that are currently certificated for operation in icing conditions rather than only turbo-propeller aircraft equipped with pneumatic deice boots. The FAA stated that in response to Safety Recommendation A-98-100, it issued airworthiness directives (ADs) for existing aircraft similar in design to the ATR-72 airplane involved in the October 31, 1994, icing accident over Roselawn, Indiana, and an EMB-120 involved in the January 9, 1997, icing accident over Monroe, Michigan. In addition, the FAA is planning to revise the regulations in Part 121 (1) to address when the ice protection system should be activated and (2) to provide a less subjective means of determining when to exit icing conditions. The FAA believes that its actions are appropriate for both turbopropeller and turbojet airplanes. The FAA’s October 26, 2005, response to Safety Recommendation A-98-100 indicated that the FAA believed the icing certification regulations and advisory material were sufficient to determine whether additional actions were needed to correct unsafe conditions on airplanes certificated at that time. The FAA further stated that it had determined that no unsafe conditions existed that warranted actions beyond those that had already been completed or were in the process of being completed. On May 10, 2006, the Board responded to the FAA that it agreed that suitable information was available to determine whether additional action was required. However, the Board did not agree that the FAA had applied the new information to all appropriate airplanes in service. The FAA found that there were no airplanes for which an unsafe condition existed, and the Board was concerned that the FAA had based its conclusion primarily on the absence of accidents or serious incidents. To meet the intent of Safety Recommendation A-98-100 (and now A-07-16), the FAA will need to formally evaluate (perhaps by conducting flight tests on) all existing pneumatic deice boot-equipped airplanes that are currently certificated for operation in icing conditions to ensure that these aircraft comply with all current icing certification criteria for new aircraft. In the May 10, 2006, letter, the Board asked the FAA to supply a list of those aircraft that it had formally evaluated and a summary of the findings and resultant actions. Pending receipt of such a list, Safety Recommendation A-98-100 was classified Open Unacceptable Response. The FAA has not supplied such a list of aircraft evaluated and resultant actions. Pending our receipt and review of a list of those aircraft that the FAA has formally evaluated and a summary of the findings and resultant actions, Safety Recommendation A-07-16 remains classified OPEN -- UNACCEPTABLE RESPONSE.

From: NTSB
To: FAA
Date: 7/23/2007
Response: Notation 7903: The National Transportation Safety Board has reviewed the Federal Aviation Administration’s (FAA) Notice of Proposed Rulemaking (NPRM), “Activation of Ice Protection; Proposed Rule,” which was published at 72 Federal Register 20924 on April 26, 2007. The notice proposes to amend Federal Aviation Regulation (FAR) Part 25 to require a means to ensure timely activation of the airframe ice protection system (IPS) on newly certified transport category airplanes for flight in icing conditions. Specifically, the rule would require that airplane manufacturers provide one of the following methods to detect ice and to ensure that the airframe IPS is activated: • automatic activation, or • installation of an ice detection system that alerts the crew to activate the IPS, or • the identification and publication of environmental conditions conducive to icing for use by the crew to activate the IPS. The NPRM states that the proposed rule will partially address Safety Recommendations A-96-56 and A-98-91 issued by the Safety Board: Revise the icing certification testing regulation to ensure that airplanes are properly tested for all conditions in which they are authorized to operate, or are otherwise shown to be capable of safe flight into such conditions. If safe operations cannot be demonstrated by the manufacturer, operational limitation should be imposed to prohibit flight in such conditions and flightcrews should be provided with the means to positively determine when they are in icing conditions that exceed the limits for aircraft certification. (A-96-56) Require manufacturers and operators of modern turbopropeller-driven airplanes in which ice bridging is not a concern to review and revise the guidance contained in their manuals and training programs to include updated icing information and to emphasize that leading edge deicing boots should be activated as soon as the airplane enters icing conditions. (A-98-91) In reviewing the proposed rule changes, the Safety Board is pleased that the FAA agrees that the regulations regarding flight in icing conditions need to be improved. The NPRM proposes an alerting system for icing conditions that exceed the limits of aircraft certification, as recommended in part by A-96-56, by adding section 25.1419(e). The NPRM proposes to address A-07-14 in part, which supersedes A-98-91 (discussed later in this response), by requiring IPS activation as soon as the airplane enters icing conditions. However, it is only an NPRM and regulatory changes may be years away. It has been almost 11 years since the Safety Board issued Safety Recommendation A-96-56 as a result of the October 31, 1994, in-flight icing encounter and loss of control of American Eagle Flight 4184, an ATR-72, over Roselawn, Indiana (Safety Board accident DCA95MA001), and 9 years have passed since the issuance of A-98-91, issued as a result of the January 9, 1997, Monroe, Michigan, Comair EMB-120 accident (Safety Board accident DCA97MA017). The Safety Board has investigated several more accidents involving in-flight icing since then, including the following: • March 14, 1997, Detroit, Michigan, Reno Air MD-87 (accident CHI97FA083) • March 19, 2001, West Palm Beach, Florida, Comair EMB-120 (accident DCA01MA031) • February 16, 2005, Pueblo, Colorado, Circuit City Citation 560 (accident DCA05MA037) • September 8, 2006, Santa Maria, California, American Eagle SF340B (accident LAX06IA076) Ice-related accidents like these are likely to continue unless the airplane certification regulations are updated to include the icing knowledge and research developed over the past decade. The Safety Board therefore encourages the FAA to act expeditiously on ice certification regulations and IPS activation requirements, including guidance materials and training programs. The Safety Board would like to see the following issues also addressed in the proposed rule. The first issue is the ongoing disconnect between industry’s current guidance on deice boot activation and what the FAA has learned and research has shown about ice bridging and deice boot effectiveness. Information gathered from the FAA’s 1997 Airplane Deice Boot Bridging Workshop, as well as subsequent icing tunnel and flight tests, revealed that ice bridging does not occur on modern airplanes, which is contrary to what has previously been thought and why some manufacturers’ guidance addresses delayed activation of deice boots. In addition, icing tunnel tests conducted by the National Aeronautics and Space Administration have shown that thin, rough ice accumulations on the wing leading edge deice boot surfaces (like the 1/4 inch or less prescribed by some manufacturers before boot activation) can, depending on distribution, be as aerodynamically detrimental to an airplane’s performance as larger ice accumulations. As a result, deice boots should be operated at the first sign of ice. Delays intended to prevent ice bridging are inappropriate, given the results of current research, and manufacturers’ guidance to operators must be revised accordingly. For example, Cessna operating procedures for the 208 Caravan (C-208) instruct crews to wait for 1/4 to 3/4 inch of ice to accrete before activating the C 208 pneumatic boots. The NPRM, on the other hand, prescribes turning on ice protection at the first sign of ice accretion (or even before, if the conditions are right). As a result of the Safety Board’s investigation of the February 16, 2005, Cessna Citation 560 accident at Pueblo, Colorado, the Safety Board issued Safety Recommendation A-07-14, which superseded A-98-91: Require manufacturers and operators of pneumatic deice boot-equipped airplanes to revise the guidance contained in their manuals and training programs to emphasize that leading edge deice boots should be activated as soon as the airplane enters icing conditions. (A-07-14) The Safety Board encourages the FAA to address this recommendation in the final rule by addressing the ice bridging issue directly to ensure that manufacturers revise the guidance in their manuals and training programs so that operators receive clear, complete, and unambiguous guidance on deice boot activation, as set forth in Safety Recommendation A-07-14. The second issue is the need for more specific guidance with respect to the identification of environmental conditions conducive for icing, the third method of compliance offered in the NPRM. As stated in Safety Recommendation A-07-14, the Safety Board believes that the IPS should be activated “as soon as the airplane enters icing conditions,” which may include visible moisture and the requisite outside air temperature. The FAA, however, has been reluctant to support IPS activation without the presence of ice, citing concerns of reduced IPS life and airplane performance. Most recently, on April 3, 2007, the FAA issued a letter of interpretation for comment in the Federal Register (Docket No. FAA-2007-27758) seeking clarification from industry on the subject of “known icing.” In it, the FAA stated that “Permutations on the type, combination, and strength of meteorological elements that signify or negate the presence of known icing conditions are too numerous to describe….” It is the Safety Board’s position that industry cannot realistically be expected to implement the third method in the proposed rule until the FAA provides a more specific definition of “environmental conditions conducive to icing.” Understandably, industry has concerns about decreased system life and airplane performance and therefore hesitates to direct operators to activate an IPS based solely on icing potential. The FAA should use the research it has commissioned through the Aviation Rulemaking Advisory Committee to provide a more detailed description of conditions conducive to icing. Until the FAA provides specific environmental parameters and prescribed levels, the third method proposed to address activation of the IPS, despite being the most proactive solution, will not be practical. The third issue is that the proposed rule does not address operations when certain functions of the IPS are known to be inoperable. Since the proposed rule would alert crews to icing conditions, the Safety Board believes that the proposed rule should prohibit crews from operating when certain functions of the IPS are inoperable. This situation occurred on January 2, 2006, when American Eagle flight 3008, a SAAB SF340B, departed San Luis County Regional Airport, San Luis Obispo, California, with a scheduled destination of Los Angeles International Airport. The airplane encountered icing conditions during the en route climb and departed controlled flight at an altitude of about 11,500 feet mean sea level (msl), descending to an altitude of about 6,500 feet msl. During the previous inbound flight and subsequent incident flight, the airplane’s automatic deice control was inoperable due to a deicer timer light failure. According to American Eagle’s Minimum Equipment List, the crew could dispatch the airplane into known or forecast icing conditions with the automatic function of the IPS inoperable. The proposed rule does not address such operations—that is, operations with an inoperable automatic IPS. The Safety Board believes that the proposed rule should prohibit flight into known icing if certain functions of the IPS are inoperable. Finally, because ice is a major safety issue that affects all airplanes, regardless of age, the Safety Board believes that the proposed rule should be expanded beyond newly certificated airplanes to include deice boot-equipped airplanes currently certified for flight in icing conditions. The Board hopes that the FAA will apply the new certification standards to ensure timely IPS activation, developed as a result of this NPRM, to earlier recommendations related to icing certification criteria (see Safety Recommendations A-96-54 and A-98-92), so that accidents like the EMB-120 accident in Monroe, Michigan, will not reoccur. The Safety Board stated this concern 9 years ago by issuing Safety Recommendation A-98-100, as a result of the accident in Monroe, Michigan: When the revised icing certification standards and criteria are complete, review the icing certification of all turbopropeller-driven airplanes that are currently certificated for operation in icing conditions and perform additional testing and take action as required to ensure that these airplanes fulfill the requirements of the revised icing certification standards. (A-98-100) This recommendation was classified “Closed–Unacceptable Action/Superseded” with the issuance of Safety Recommendation A-07-16 to the FAA on February 27, 2007, issued as a result of the February 16, 2005, Pueblo, Colorado, Cessna Citation 560 accident. The prior recommendation addressed turbopropeller airplanes; however, the Citation 560 involved in the Pueblo accident was a deice boot-equipped turbojet. The circumstances of the Pueblo accident demonstrated that pneumatic deice boot-equipped turbojet airplanes also require review and testing to meet the expanded icing certification standards. Hence, this new recommendation, A 07-16, reiterates the point that certification requirements should apply to currently certified deice boot-equipped aircraft, as well as new aircraft: When the revised icing certification standards (recommended in Safety Recommendations A-96-54 and A-98-92) and criteria are complete, review the icing certification of pneumatic deice boot-equipped airplanes that are currently certificated for operation in icing conditions and perform additional testing and take action as required to ensure that these airplanes fulfill the requirements of the revised icing certification standards. (A-07-16) The Safety Board supports issuance of the regulatory revisions proposed in this NPRM. Ice is detrimental to airplane performance and handling qualities, and it represents a serious threat to aviation safety. The Board has investigated many accidents caused by in-flight icing. Operators need to be fully informed before entering icing conditions, and the proposed rule should help do this. However, the Board continues to believe that the issues outlined above—bridging, clearer guidance on deice activation, operation with a known inoperative IPS, and applying revised certification standards to previously certified airplanes—should be addressed in the proposed rule. The Safety Board appreciates the opportunity to comment on this NPRM.

From: FAA
To: NTSB
Date: 5/17/2007
Response: Letter Mail Controlled 5/31/2007 8:48:32 AM MC# 2070240: - From Marion C. Blakey, Administrator: 5/17/07 This safety recommendation supersedes A-98-100. In response to safety recommendation A-98-100, we have taken certain actions for the safe operation of turbopropeller-driven airplanes in icing conditions. We are aware of the lessons learned from two major accidents, the ATR-72 accident in Roselawn, Indiana and the EMB-120 accident in Monroe, Michigan, which occurred in 1994 and 1998, respectively. We issued airworthiness directives (AD) against existing aircraft of designs similar to the accident airplanes (see enclosure). In addition, after a general review of icing accidents and incidents the FAA began a rulemaking project to amend the 14 CFR part 121 operating rules to improve the safety of the fleet. The proposed part 121 rule, in addition to those described in our October 2005 response to the Board, improves ice protection activation means and requires less subjective means of determining when the flightcrew should exit icing conditions. This rule is applicable to all booted airplanes. We believe these Ads and the planned part 121 rule will incorporate the lessons learned from both the Roselawn and Monroe accidents for existing turbopropeller-driven airplanes in service. As a result of the issuance of A-07-16, we have reexamined our position and find that our actions are appropriate for both turbopropeller and turbojet-driven airplanes, because many of the FAA actions were applicable to both types of airplanes. The FAA will take additional action for specific airplane models if we find evidence that an unsafe condition exists or is likely to develop in any in-service airplane type.

From: NTSB
To: FAA
Date:
Response: At the 1997 Board meeting addressing the NTSB’s Most Wanted List of Transportation Safety Improvements (MWL), the Board voted to place Safety Recommendations A-96-54 through A-96-56, A-96-62, and A-96-69 on the MWL under the issue category “Airframe Structural Icing.” The Board voted to add Safety Recommendations A-98-92, A-98-94, A-98-95, A-98-99, A-98-100, A-07-14 at later dates. Safety Recommendation A-07-16 was added to the MWL upon its adaptation because it supersedes Safety Recommendation A-98-100.