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Safety Recommendation Details

Safety Recommendation A-07-014
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: 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) (This safety recommendation supersedes Safety Recommendation A-98-91)
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: 12/18/2012
Addressee(s) and Addressee Status: FAA (Closed - Unacceptable Action)
Keyword(s): Icing

Safety Recommendation History
From: NTSB
To: FAA
Date: 5/12/2016
Response: Correspondence control 201600220, Dated May 12, 2016: The National Transportation Safety Board (NTSB) has reviewed the Federal Aviation Administration’s (FAA) notice of proposed rulemaking (NPRM) titled “Revision of Airworthiness Standards for Normal, Utility, Acrobatic, and Commuter Category Airplanes,” which was published at 81 Federal Register (FR) 13451 on March 14, 2016. The NPRM proposes to amend airworthiness standards for normal, utility, acrobatic, and commuter-category airplanes by removing prescriptive design requirements and replacing them with performance based airworthiness standards. The proposed standards would also replace the current weight and propulsion divisions in small airplane regulations with performance- and risk based divisions for airplanes with a maximum seating capacity of 19 passengers or less and a maximum takeoff weight of 19,000 lbs. or less. In addition, the NPRM proposes to adopt additional airworthiness standards to address certification for flight in icing conditions, enhanced stall characteristics, and minimum control speed to prevent departure from controlled flight for multiengine airplanes. On April 8, 2016, the FAA also published on its website draft Advisory Circular (AC) 23.10 titled “FAA Accepted Means of Compliance Process for 14 [Code of Federal Regulations] CFR Part 23.” The draft AC provides guidance on how to submit a proposed means of compliance (MOC) with Part 23 for acceptance by the Administrator in accordance with proposed section 23.10, “Accepted Means of Compliance,” in the NPRM. This letter provides comments on the NPRM. We will submit separate comments regarding draft AC 23.10. We agree with the FAA’s statement in the NPRM that section 23.1405 addresses Safety Recommendations A-07-14 and-15, which we issued on February 27, 2007: A-07-14 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. [Classified “Closed—Unacceptable Action”] A-07-15 Require that all pneumatic deice boot-equipped airplanes certified to fly in known icing conditions have a mode incorporated in the deice boot system that will automatically continue to cycle the deice boots once the system has been activated. [Classified “Closed—Acceptable Alternate Action”] However, we do not agree that proposed section 23.1405 addresses or is relevant to Safety Recommendation A-10-12, which concerns low-airspeed alerting systems. We believe that proposed section 23.1500, “Flightcrew Interface,” is more appropriate for addressing the safety issue identified in this recommendation, which we issued on February 23, 2010: A-10-12 For all airplanes engaged in commercial operations under 14 [CFR] Parts 121, 135, and 91K, require the installation of low-airspeed alert systems that provide pilots with redundant aural and visual warnings of an impending hazardous low speed condition. [Classified “Open—Acceptable Response”]

From: NTSB
To: FAA
Date: 12/18/2012
Response: On June 2, 2011, we noted the FAA’s progress in responding to this recommendation with its August 3, 2009, publication of the final rule revising Part 25 regulations concerning the activation of ice protection systems and the publication of the final rule titled “Activation of Ice Protection,” effective on October 21, 2011, applicable to Part 121 operations. On March 27, 2011, the FAA stated that, as discussed in the notice of proposed rulemaking that was the basis for its October 21, 2011, final rule, it agreed with the conclusion of the FAA’s Aviation Rulemaking Advisory Committee’s Ice Protection Harmonization Working Group that similar rules for Parts 91 and 135 were not required. On June 2, 2011, we asked the FAA to reconsider its decision not to amend Parts 91 and 135 to include requirements similar to those included in the October 21, 2011, final rule. We pointed out that, in the accident that occurred in Pueblo, Colorado, that prompted this recommendation, the airplane had been operating under Part 91. The FAA’s October 21, 2011, final rule would not have corrected the circumstances regarding the deice boot operation on the accident airplane. In its current letter, the FAA replied that it has reassessed the applicability of the Part 121 Activation of Ice Protection rule to Parts 91 and 135. The FAA reviewed the accident history and did not find support for the additional rulemaking; therefore, the agency plans no further operational rulemaking related to this issue. We continue to believe that the Pueblo, Colorado, accident demonstrates that pneumatic boot–equipped aircraft operating under Part 91 may encounter icing conditions and that these operations need the requirement recommended. However, the FAA does not plan to take that action; consequently, Safety Recommendation A 07-14 is classified CLOSED—UNACCEPTABLE ACTION.

From: FAA
To: NTSB
Date: 9/27/2012
Response: -From Michael P. Huerta, Acting Administrator: In our letter dated March 8, 2012, we reported on recommendations we received from an Aviation Rulemaking Committee (ARC) concerning activation and operation of ice protection systems on new airplanes certificated under Title 14, Code of Federal Regulations (14 CFR) part 23. The Federal Aviation Administration (FAA) received a final report on February 10,2012, from this ARC that contains additional part 23 icing rulemaking recommendations. The FAA is studying these recommendations and will notify the Board if new part 23 icing rulemaking is warranted based on these recommendations. In the interim, manufacturers of part 23 airplanes have been following the guidance in Advisory Circular (AC) 23.1419-20, "Certification of Part 23 Airplanes for Flight in Icing Conditions," dated April 19, 2007. This AC recommends that the Airplane Flight Manual (AFM) procedures for activating the deice boots should be to operate the deice boots in an appropriate continuous mode at the first sign of ice. The Board's June 14, 2012, letter indicated that Safety Recommendation A-07-14 will remain classified "Open-Unacceptable Response" pending the establishment of ice protection system activation requirements in parts 91 and 135 similar to those enacted on October 21, 2011, for aircraft operated under part 121. We have reassessed the implementation of the part 121 rule and its applicability to parts 91 and 135 operations. Based on our review, we maintain that the current implementation provides an adequate level of safety as described in the preamble to the rule. Therefore, we plan no further operational rulemaking related to this issue. While we agree with the Board that removing subjectivity from activation of the airframe ice protection system would he an improvement, our review of the accident history does not support additional rulemaking. In the case of the Pueblo accident, the crew was clearly aware that icing conditions existed at the time, yet chose not to follow their AFM procedures to cycle the deicing boots prior to approach. If required in the future, the FAA will take action by issuing an airworthiness directive for specific model airplanes if warranted by service history. As additional mitigation applicable to all icing operations, the FAA conducted research on low airspeeds typical of small airplanes, which showed that the benefits of "early and often" boot cycling has to be weighed against workload in the single pilot operations of an airplane with a manual (no automatic timer) boot system. This research was published in 2007 by the American Institute of Aeronautics and Astronautics (paper number 2007-1090, "Residual and Inter-cycle Ice for Lower-Speed Aircraft with Pneumatic Boots"). We also summarized this research in AC 91-74A, "Pilot Guide: Flight in Icing Conditions." We have written educational materials and will continue to write educational materials that stress: • Following the AFM, but early and often boot cycling cannot hurt and can only help airplanes with modem boots; • Residual ice may be noted after cycling but it is not "ice bridging;" • Cycling boots prior to configuring the airplane for approach; and • Using ice adhesion treatments as recommended by the boot manufacturer. I will keep the Board informed of our progress on these safety recommendations and provide an update by August 30, 2013.

From: NTSB
To: FAA
Date: 6/14/2012
Response: On June 2, 2011, we recognized the FAA’s progress in responding to this recommendation with its August 3, 2009, publication of the final rule revising Part 25 regulations concerning the activation of ice protection systems. More recently, the FAA published a final rule titled “Activation of Ice Protection,” effective on October 21, 2011, which applies to Part 121 operations. On March 27, 2011, the FAA stated that, as discussed in the notice of proposed rulemaking that was the basis for its October 21, 2011, final rule, it agreed with the conclusion of the FAA’s Aviation Rulemaking Advisory Committee’s Ice Protection Harmonization Working Group that similar rules for Parts 91 and 135 were not required. In our previous letter, we asked the FAA to reconsider its decision not to amend Parts 91 and 135 to include requirements similar to those included in the October 21, 2011, final rule. We pointed out that, in the accident that occurred in Pueblo, Colorado, which prompted this recommendation, the airplane had been operating under Part 91. The FAA’s then planned (and now implemented) action would not have corrected the circumstances regarding the deice boot operation on the Cessna 560. The FAA’s current letter does not address our request that the FAA reconsider its decisions regarding the recommended action for Parts 91 and 135 in view of the circumstances of the Pueblo accident. Accordingly, pending the establishment of requirements in Parts 91 and 135 similar to those enacted on October 21, 2011, for aircraft operated under Part 121, Safety Recommendation A-07-14 remains classified OPEN—UNACCEPTABLE RESPONSE.

From: NTSB
To: FAA
Date: 4/30/2012
Response: Notation 8406: The National Transportation Safety Board (NTSB) has reviewed the Federal Aviation Administration’s (FAA) notice of proposed rulemaking (NPRM) titled “Pilot Certification and Qualification Requirements for Air Carrier Operations,” which was published at 77 Federal Register (FR) 12374 on February 29, 2012. The notice proposes to create new certification requirements for pilots in air carrier operations, including requiring that first officers in 14 Code of Federal Regulations (CFR) Part 121 operations hold an airline transport pilot (ATP) certificate and type rating for the aircraft to be flown; allowing pilots with an aviation degree or military pilot experience but fewer than 1,500 hours total time as a pilot to obtain an ATP certificate with restricted privileges; and requiring at least 1,000 flight hours in air carrier operations to serve as pilot in–command (PIC) in Part 121 air carrier operations. The notice also proposes to modify the requirements for obtaining an ATP certificate with an airplane category multiengine class rating or type rating to require 50 hours of multiengine flight experience and completion of a new FAA-approved ATP certificate training program that would include academic training and training in a flight simulation training device. According to the NPRM, these changes would help to ensure that pilots entering an air carrier environment have the training and aeronautical experience necessary to adapt to a complex, multicrew environment in a variety of operating conditions. The NPRM cites the 2009 Colgan Air accident near Buffalo, New York, as an event that focused public, congressional, and industry attention on flight crew experience requirements and training for conducting Part 121 air carrier operations. In February 2010, the FAA published an advance notice of proposed rulemaking (ANPRM), titled “New Pilot Certification Requirements for Air Carrier Operations” (75 FR 6164, February 8, 2010) that sought input on current Part 121 eligibility, training, and qualification requirements for seconds-in-command (SICs). The current NPRM is based on comments in response to the ANPRM, input received from an aviation rulemaking committee established in July 2010, and statutory requirements for modifying ATP certification outlined in the Airline Safety and Federal Aviation Administration Extension Act of 2010 (Public Law 111-216). Adding to that foundation, the NPRM states that the FAA conducted a study of 61 NTSB investigation reports from fiscal year (FY) 2001 through FY 2010 (31 Part 121 accidents and 30 Part 135 air carrier accidents, with 107 fatalities, 28 serious injuries, and 44 minor injuries). The study showed that the accidents examined involved pilot deficiencies in aircraft handling, including stall and upset recognition and recovery, high altitude training, active pilot monitoring skills, effective crew resource management (CRM), stabilized approaches, operations in icing conditions, and hypoxia training. The NPRM asserts that the changes to air carrier pilot qualification would address, in part, 21 NTSB safety recommendations in the following areas: Safety Issue Recommendations Training flight crews to respond to sudden, unusual, or unexpected aircraft upsets: A-96-120, A-04-62, A-07-3, and A-09-113 Developing and conducting stall recovery training and providing stickpusher familiarization training for pilots of stickpusher-equipped aircraft: A-10-22 and -23 Training in high altitude operations: A-07-1 and -2 Training and guidance for rudder use in transport-category aircraft: A-02-2 Airport situational awareness: A-07-44 Stabilized approach concept: A 01 69 and A-08-18 Landing performance calculations: A-07-59 and A-08-41 CRM training: A-03-52 Pilot monitoring duties: A-10-10 Requirements for flight crewmember academic training regarding leadership and professionalism: A-10-15 Training in icing conditions: A-07-14 Hypoxia awareness training: A 00 110 Training in landing and taking off in crosswinds with gusts: A 10-110 and -111 The NTSB is generally supportive of the proposed rule as it relates to many of the issues previously identified in our safety recommendations. Specific comments on several areas of the NPRM follow. Academic Credit To Reduce Flight Experience Requirements Although the NTSB has not made recommendations for flight hour minimums for air carrier pilots (instead focusing its recommendations on specific procedures and training, needed regulations, and needed guidance to crews and operators), we stated in our comments on the ANPRM that: Ensuring a high level of knowledge, skills, and professionalism for flight crewmembers is essential, but total flight hours or an airline transport pilot certificate does not necessarily equate to the level of knowledge, skills, and professionalism required for consistently safe flight operations. The comments went on to state that, “the NTSB recognizes the value of academic training for air carrier pilots, but the NTSB also believes that academic training is not a substitute for practical experience.” An important tenet in the recent NPRM is the concept that, “in certain circumstances, the combination of focused academic training and structured flight training can substitute for actual flight experience” (p. 12379). The NTSB concurs with the FAA’s acknowledgement that there may be multiple pathways to becoming a qualified air carrier pilot. However, there remain unresolved issues for how academic credit should be applied, including student performance within an accredited academic program and the type of degree conferred. These issues are not addressed in the NPRM and require more evaluation before this proposal is implemented. It is essential that the content and rigor involved in academic training be clearly defined and, most importantly, appropriate resources allocated to conduct evaluation and oversight of these alternative methods of qualification. ATP Certification Training Program The NPRM discusses the establishment of an FAA-approved ATP certificate training program for a multiengine class ATP or type rating. The proposed training program outlined under section 61.154 would include 24 hours of classroom training and 16 hours of simulator training (8 in a full flight simulator of at least Level C standards) and is intended to provide pilots with the core knowledge and understanding in areas critical to operating high performance aircraft in a complex and high altitude environment. The training would be provided by an authorized training provider and would be required to be completed before a pilot would be eligible to take the ATP knowledge test. Issued as part of the NPRM, draft Advisory Circular (AC) 61-ATP, “Airline Transport Pilot Certification Training Program for Airplane Category Multiengine Class Rating or Type Rating,” contains an outline of the curriculum topics and objectives for both the classroom and simulator training making up this training program. The AC is intended for use by training providers when developing the program and by the FAA when reviewing and approving the programs. Many of the topics contained in the draft AC address issues from NTSB safety recommendations; in fact, the FAA notes that most of the 21 recommendations cited in the NPRM are addressed, in part, by the proposed amendments and advisory material. Although the NTSB concurs with the FAA’s assessment that, in most cases, the topics addressed will serve to partially satisfy the action requested in existing recommendations, the amount of specificity provided in the proposed rule and AC does not allow a comprehensive review of the degree to which the FAA’s proposed actions would satisfy the intent of the NTSB’s recommendations. In some instances, neither document provides evidence that a recommendation topic is addressed. The NTSB notes that recent safety recommendations in this area have focused on attempts to improve crew response to in-flight emergencies, including task prioritization and training. While AC 61-ATP does include a classroom training objective named “differences between emergency and non-normal checklist procedures and checklists,” the guidance on emergency procedures should be made more explicit to incorporate the issues identified in these NTSB recommendations. CRM is another topic relevant to previous NTSB recommendations and outlined in AC 61-ATP. However, the list of proposed topics in the AC does not explicitly refer to the importance of first officer assertiveness, which is an issue addressed in Safety Recommendation A-11-39. This recommendation is not cited in the NPRM, but the NTSB believes that it is within the scope of the draft advisory material and suggests amending the AC to include information consistent with Safety Recommendation A-11-39 to help support this important aspect of CRM. The NTSB is encouraged that the NPRM proposes to centralize the process for approving ATP certification training programs. Specifically, the NPRM states that only authorized training providers can administer the training required under section 61.154. These providers can be certificate holders providing training and operating under Parts 141, 142, 121, or 135, and each provider must receive approval of their ATP certification training program by the FAA Air Transportation Division (AFS-200). The NTSB notes that, theoretically, centralization should help to ensure standardization of these programs, but suggests that additional guidance documentation with more specific and robust detail about the content of the proposed training is necessary to provide a solid foundation on which the FAA can evaluate the program content (and to assist training providers to develop courses likely to receive FAA approval). For example, additional detail, such as cross-referencing material from draft AC 120-STALL, would be appropriate in the discussion of stall training in AC 61-ATP. In addition, the FAA will need to provide the appropriate oversight resources to these programs—not only in their initial approval but also to conduct ongoing oversight to demonstrate that the content delivered is consistent with the approved program. The rigor with which these programs are implemented and overseen will determine their ultimate influence on improving safety in air carrier operations. Pilot-in-Command Requirements for Air Carrier Operations The NPRM proposes primarily experience-based requirements for new PICs in air carrier operations. However, the NTSB has previously issued safety recommendations addressing the need for a specific leadership training course for upgrading captains. Although the NPRM cites Safety Recommendation A-10-15 and describes it as applicable to leadership and professionalism training, it addresses only the latter topic. The NPRM does not mention Safety Recommendations A-10-13 and -14, which were issued with -15, but the NTSB believes that a leadership training course for upgrading captains is within the scope of the proposed rulemaking and that section 121.436 should be amended to include a specific requirement for such a course. In addition to the requirements already outlined in section 121.434, the NTSB has recommended that Part 135 pilots who need a type rating for the aircraft they fly be required to have a minimum level of initial operating experience. Given the applicability of the NPRM to Part 135 pilots who are engaged in air carrier operations, the NTSB believes it would be appropriate to incorporate similar experience requirements for these pilots as exist for Part 121 pilots. The NTSB supports the use of simulators in training environments and notes that the training program outlined in the NPRM specifies that training on topics such as low energy states/stalls and upset recovery techniques will be conducted in a Level C or higher full-flight simulator. Simulators, regardless of their fidelity, are dependent on their physical limits of motion, as well as the efficacy of the available computer programs (which are often limited in issues of upset training because of the lack of flight test data at the extreme areas of the flight envelope). Simulators are not always adequate in portraying upsets and stalls and may inadvertently introduce negative training. Consistent with Safety Recommendation A-04-62, the FAA should allow flexibility in determining what level of simulation or automation is appropriate for specific training. Summary Observations This NPRM addresses many training issues applicable to becoming an air carrier pilot, including some critical issues demonstrated in recent accident history to be responsible for accidents. The NTSB is encouraged that its recommendations were considered in the development of this proposed rule, especially as the issue areas relate to the core content to be provided to new entrant pilots through the ATP certification training program. However, the intent of our recommendations in this area is for all pilots to receive training in these topics. Therefore, it is important that air carriers provide equally robust training in these topic areas for their current air carrier pilots on a recurrent basis. The NTSB appreciates the opportunity to comment on this NPRM.

From: FAA
To: NTSB
Date: 3/8/2012
Response: -From Michael P. Huerta, Acting Administrator: In the Federal Aviation Administration's (FAA) March 27, 2011, letter, we reported we published a notice of proposed rulemaking (NPRM) requiring timely activation of the airframe ice protection system (IPS) for certain airplanes used in part 121 operations that are certificated for flight in icing conditions. We published a final rule, Activation of Ice Protection (76 FR 52241) on August 22, 2011, and it became effective on October 21, 2011. The rule, which applies to airplanes with a maximum takeoff weight or less than 60,000 pounds requires either installation of ice detection equipment or changes to the airplane night or operating manual to ensure timely activation of the airframe IPS. The standards also require the airplane flight or operating manual to address initial activation, operation after initial activation, and deactivation of the airframe IPS. Depending on the IPS design, continuous operation, automatic cycling, or manual cycling can be used. For airplanes equipped with ice detection systems, the IPS must be cycled each time ice is detected. Operators must comply with these new standards by October 21, 2013. We also reported in our March 27, 2011, letter, that we received Aviation Rulemaking Committee (ARC) recommendations on February 22, 2011 concerning activation and operation of the airframe IPS for new part 23 airplane designs. In the interim, manufacturers of part 23 airplanes have been following the guidance in Advisory Circular (AC) 23.1419-2D, which recommends that the Airplane Flight Manual (AFM) procedures for activating the boots should be to operate the boots in an appropriate continuous mode at the first sign of ice. I will keep the Board informed on the progress of these safety recommendations by August 29, 2012.

From: NTSB
To: FAA
Date: 6/2/2011
Response: On April 27, 2010, the NTSB recognized the FAA’s progress in responding to this recommendation by the FAA’s August 3, 2009, publication of the final rule revising Part 25 regulations concerning the activation of ice protection systems and its November 23, 2009, publication of a notice of proposed rulemaking (NPRM), titled “Part 121 Activation of Ice Protection.” At its February 18, 2010, meeting to review the Most Wanted List, the Board voted to retain the classification “Open—Acceptable Response” pending issuance of a final rule for timely activation of the ice protection system (IPS) that includes flights operated under Parts 91 and 135. In its current letter, the FAA stated that, as discussed in the NPRM, its Aviation Rulemaking Advisory Committee’s Ice Protection Harmonization Working Group concluded that similar rules for Parts 91 and 135 were not required, that the FAA agrees with the working group, and that the FAA therefore plans no action related to IPS activation for Parts 91 and 135. In the NPRM, the FAA offered the following reasons for the decision to exempt aircraft operated under Parts 91 and 135: 1. These aircraft are typically smaller than those operated under Part 121, and their smaller scale allows pilots to monitor ice accretions more easily. 2. Part 91 and Part 135 aircraft are often operated in a lower air traffic density, which results in fewer holding delays and significantly more routing options in icing conditions. 3. Most aircraft operated under Parts 91 and 135 have been subjected to airworthiness directives (AD) that require activation of the airframe’s IPS at the first sign of ice accretion on the airplane. However, in the NPRM, the FAA indicated that identifying ice accumulations can be difficult for crews of aircraft subject to these ADs. Activation of the deicing boots is still subject to the flight crew’s observation of ice accretions, and such observations can be difficult during times of high workload, during operations at night, or when clear ice has accumulated. The problems associated with observing ice accretions are applicable to any airframe’s IPS that relies on the flight crew’s observation for activating the system, not only pneumatic deicing boots. As a result, these ADs do not adequately address the safety concerns that are the focus of the NPRM. On February 23, 2010, in comments that we submitted to the docket for this NPRM, we stated that the accident that prompted Safety Recommendation A-07-14 illustrates why we disagreed with the reasons given for the NPRM’s not covering Parts 91 or 135 operations. In this accident, the airplane was operating under Part 91, the AD for activation of the deice boots had been withdrawn, and the procedures in place required the flight crew to observe a prescribed amount of ice before they were to activate the deice boots. If the FAA’s planned action in response to this recommendation had been completed, the circumstances regarding the deice boot operation on the Citation 560 that existed prior to the Pueblo accident would still exist. In our NPRM comments we also stated that the NPRM exempted aircraft with a mean takeoff weight (MTOW) greater than 60,000 pounds, such as the Bombardier Q400 that had been involved in the February 12, 2009, Colgan Airlines accident in Clarence Center, New York. Safety Recommendation A-07-14 recommends that all deice boot-equipped airplanes currently in service, regardless of their MTOW weight limit, be subject to the requirements proposed in the NPRM. The NTSB asks the FAA to reconsider its decision not to revise the regulations for Parts 91 and 135 to include requirements similar to those in its Part 121 IPS activation NPRM, in light of the circumstances of the February 16, 2005, accident in Pueblo, Colorado. Pending issuance of a final rule based on the Part 121 IPS activation NPRM that does not include an exclusion for aircraft with a MTOW greater than 60,000 pounds, and a similar requirement for aircraft operated under Parts 91 and 135, Safety Recommendation A-07-14 is classified OPEN – UNACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 3/27/2011
Response: CC# 201100127: - From J. Randolph Babbitt, Administrator: In the Federal Aviation Administration's September 22, 2009 letter, we reported the Part 25 Activation of Ice Protection final rule was published on August 3, 2009. This rule addresses all newly certificated part 25 aircraft and became effective September 8, 2009. On November 23, 2009, we published a notice of proposed rulemaking (NPRM) for activation of ice protection of certain airplanes used in part 121 operations and certificated for flight in icing conditions. The proposed standards would require either installation of ice detection equipment or changes to the Airplane Flight Manual (AFM) to ensure timely activation of the airframe ice protection system. The standards would also require continuous or automatic operation of ice protection systems after activation. As discussed in this NPRM, the Aviation Rulemaking Advisory Committee's Ice Protection Harmonization Working Group concluded that similar rules for part 91 and 135 are not required. The FAA agrees and plans no action related to activation of ice protection on parts 91 and 135 at this time. The NPRM comment period closed February 22, 2010 and we anticipate publishing the final rule by July 2011. We also reported in our September 22, 2009 letter that manufacturers of part 23 airplanes have been following the guidance in Advisory Circular (AC) 23.1419-2D, which recommends operation of deicing boots at the first sign of icing and in an appropriate continuous mode. We chartered an Aviation Rulemaking Committee on February 19, 2010 to address part 23 icing regulations, which includes activation and operation of ice protection systems for new part 23 airplanes. The Part 23 Icing Aviation Rulemaking Committee delivered a report to the FAA Small Airplane Directorate on February 22, 20 II. The report includes recommendations for part 23 rulemaking on ice protection activation and operation, which address Safety Recommendations A-07-14 and -15. We are currently reviewing these recommendations to support future rulemaking efforts.

From: NTSB
To: FAA
Date: 4/27/2010
Response: The NTSB recognizes the recent progress made by the FAA in publishing its August 3, 2009, final rule revising Part 25 regulations concerning the activation of ice protection systems and its November 23, 2009, NPRM, titled Part 121 Activation of Ice Protection. However, the NTSB remains concerned about the overall slow pace in completing the recommended actions, particularly the FAA’s failure to address Parts 91 and 135 operations and its exemption of aircraft with a mean takeoff weight greater than 60,000 pounds; these serious shortcomings must be addressed before action on the recommendations can be considered successfully completed. At its February 18, 2010, meeting, the Board voted to retain the classification “Open—Acceptable Response” pending issuance of a final rule for timely activation of the ice protection system that includes flights operated under Parts 91 and 135. With regard to Safety Recommendation A-07-15, the FAA’s August 3, 2009, final rule meets the intent of the recommendation for Part 25 airplanes. The FAA now needs to implement, in a timely manner, a similar requirement for Part 23 airplanes; as stated above, the NTSB remains concerned about the slow pace of the progress to implement the needed reforms. Pending implementation of a requirement for Part 23 airplanes that use pneumatic deicing boots to have a mode incorporated that will automatically continue to cycle the deice boots once the system has been activated, Safety Recommendation A-07-15 remains classified OPEN -- ACCEPTABLE RESPONSE.

From: NTSB
To: FAA
Date: 2/23/2010
Response: Notation 7903A: The National Transportation Safety Board (NTSB) has reviewed the Federal Aviation Administration (FAA) notice of proposed rulemaking (NPRM), “Part 121 Activation of Ice Protection,” published at 74 Federal Register 61055 on November 23, 2009. The NTSB evaluated the proposed rule in light of open safety recommendations related to aircraft operations in icing and in regard to other pertinent concerns identified during the course of its investigations. The proposed rule applies to operators of certain airplanes that are used in Title 14 Code of Federal Regulations (CFR) Part 121 operations and that are certificated for flight in icing conditions. Specifically, the proposed rule would require the affected airplane operators to use one of the following means of ensuring that airframe ice protection systems (IPS) are operated continuously at the first sign of ice accretion: installing a primary ice detection system, installing an advisory ice detection system, or requiring continuous operation of the airframe IPS whenever the airplane is operating in conditions conducive to airframe icing. The NPRM states that the proposed rule is based on recommendations to the FAA from the Aviation Rulemaking Advisory Committee (ARAC) Ice Protection Harmonization Working Group (IPHWG). The NPRM also states that the proposed rule will address NTSB Safety Recommendation A-07-14, issued as a result of the NTSB investigation of the February 16, 2005, Cessna Citation 560 accident at Pueblo, Colorado. This recommendation asked the FAA to take the following action: 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. To that end, the proposed regulation requires that the aircraft flight manual (AFM) address initial activation of the IPS, operation of the IPS after initial activation, and deactivation of the airframe IPS. In comments on adopted Amendment 25-129, the NTSB noted that although some manufacturers advise their operators to delay activation of deice boots as a way of preventing ice bridging, research shows that ice bridging does not occur on modern airplanes. In addition, tests conducted by the National Aeronautics and Space Administration have shown that thin, rough ice accumulations on the wing leading edge deice boot surfaces can, depending on distribution, be as aerodynamically detrimental to an airplane’s performance as larger ice accumulations. The NTSB therefore agrees with the FAA that airframe ice protection systems, including deice boots, should be operated at the first sign of ice accretion. Delays intended to prevent deice boot ice bridging are potentially hazardous, and manufacturers’ guidance to operators must be revised accordingly. The proposed rule also addresses the fact that neither current operating regulations nor icing certification regulations in effect before the recent adoption of Amendment 25-149 require a means to ensure timely activation of the IPS. The NTSB is pleased that the FAA is taking steps to ensure that AFMs are revised so that they no longer require IPS activation only after a substantial accumulation of ice. Further, the NTSB is pleased that the proposed rule would require the installation of ice detection systems or the activation of ice protection systems in conditions conducive to icing in most phases of flight. In the cruise phase of flight, the airframe IPS would be activated at the first sign of ice accumulation anywhere on the airplane. Although the NTSB agrees with the FAA stance on the above issues, it disagrees with the proposed rule in two important areas: first, that the rule would apply only to airplanes with a certificated maximum takeoff weight (MTOW) of less than 60,000 pounds and second, that the proposed rule applies to Part 121 operations only. As stated in Safety Recommendation A-07-14, the NTSB believes that, for deice boot-equipped airplanes, the IPS should be operated as soon as the airplane enters icing conditions, regardless of the size or MTOW of the airplane. However, by limiting the new requirements to aircraft of less than 60,000 pounds, the proposed rule excludes a number of aircraft models for which the new requirements would be beneficial. For example, the Bombardier Q400 involved in the February 12, 2009, Colgan Airlines accident in Clarence Center, New York (NTSB accident number DCA09MA027) has an MTOW slightly greater than 60,000 pounds and would therefore not be affected by the proposed rule. While the Bombardier Q400 is equipped with a deice boot and an ice detection system, operation of this aircraft under the requirements of the proposed rule would provide additional protection for safe operation—not only in the icing conditions for which it has been certificated (that is, 14 CFR 25, Appendix C), but also if the airplane inadvertently encounters icing conditions that exceed the atmospheric conditions for which it has been certificated. Such conditions include supercooled large droplets, which were not considered in the Bombardier Q400’s certification for flight in icing conditions and may generate aerodynamic degradation with only small amounts of ice accretion. At the time this response was written, NTSB investigators had determined that icing was not a factor in this accident. Nevertheless, the NTSB believes that the MTOW weight limit in the proposed rule should be expanded to include all deice boot-equipped airplanes currently in service, as stated in Safety Recommendation A-07-14. The second issue with which the NTSB disagrees regards limiting the proposed rule to Part 121 operations only. In the NPRM, the FAA offers several reasons for this decision. One reason is that aircraft operated under Parts 91 and 135 are typically smaller than those operated under Part 121, and this smaller scale allows pilots to monitor ice accretions more easily. The FAA states further that Part 91 and Part 135 aircraft are often operated in a lower air traffic density, which results in fewer holding delays and significantly more routing options in icing conditions. Additionally, the FAA states that most aircraft operated under Parts 91 and 135 have been subjected to airworthiness directives (AD) that specify when to activate the airframe IPS—that is, at the first sign of ice accretion on the airplane. However, the FAA also correctly notes that identifying ice accumulations can be difficult for crews of aircraft subject to these ADs: Activation of the pneumatic deicing boots is still subject to the flightcrew’s observation of ice accretions, and such observations can be difficult during times of high workload, during operations at night, or when clear ice has accumulated. The difficulties associated with observing ice accretions are applicable to any airframe IPS that relies on the flightcrew’s observation for activating the system, not just pneumatic deicing boots, so these AD’s are not adequate to address the safety concern that is the focus of this proposed rulemaking. A case in point is the airplane involved in the February 16, 2005, Pueblo, Colorado, Circuit City Citation 560 accident, which was operating under Part 91, had its AD for activation of the deice boots withdrawn, and relied on the flight crew to observe a prescribed amount of ice before activating the deice boots. These facts were the main impetus for superseding Safety Recommendation A-98-91 with A-07-14, which recommended that, for all deice boot-equipped airplanes, and for all operations including Parts 91 and 135, the FAA require manufacturers and operators to revise guidance and training programs to specify that the IPS be turned on as soon as the airplane enters icing conditions. If the proposed rule is implemented as is and does not apply to Part 91 and 135 operations, the circumstances regarding the deice boot operation on the Citation 560 that existed prior to the Pueblo accident will still exist. To summarize, the NTSB supports issuance of the Part 121 regulatory revisions proposed in this NPRM. However, the NTSB continues to believe that the issues outlined above—applying the requirements to aircraft with an MTOW greater than 60,000 pounds to include all currently in service, deice boot-equipped airplanes and applying the requirements to all Part 121, 91, and 135 operations—should be addressed in the proposed rule. Aside from these reservations, the NTSB believes that the proposed rulemaking is an essential step in improving the safety of flight in icing conditions for airplanes operating under Part 121 and directly addresses the intent of our recommendations. The NTSB appreciates the opportunity to comment on this NPRM.

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: In the FAA's May 17, 2007, letter we reported the notice of proposed rulemaking (NPRM) for the Part 25 Activation of Ice Protection, was published on April 26, 2007, and the comment period closed on July 25, 2007. The final rule, addressing all newly certificated aircraft, was published on August 3, 2009 (74 FR 38328) (enclosure 1). In January 2008, we initiated a rulemaking action to amend the regulations applicable to operators of certain airplanes used in part 121 operations and certificated for flight in icing conditions. The proposed standards would require either the installation of ice detection equipment or changes to the Airplane Flight Manual to ensure timely activation of the airframe ice protection system. We anticipate publishing the NPRM in December 2009. We also reported in our May 17, 2007, letter that manufacturers of part 23 airplanes have been following the guidance in Advisory Circular (AC) 23.1419-2D, which recommends operation of deicing boots at the first sign of icing and in an appropriate continuous mode. In March 2009, the FAA Rulemaking Management Council agreed to create an Aviation Rulemaking Committee (ARC) to address part 23 icing regulations. The ARC will be tasked with the following actions: Review the aviation rulemaking advisory committee recommendations related to the proposed part 25 regulations and guidance for supercooled large drops (SLD), mixed phase, and ice crystals, and recommend if, and how, they need to be modified for part 23; Recommend part 23 regulations that will codify the guidance in AC 23.1419-2D on activation and operations of ice protection systems, stall warning in icing conditions, and ice contaminated tailplane stall; Revise current § 23.1419 rule language on airplane performance requirements in icing that require an exemption to the 61 knot stall speed requirement in icing; and Determine if using 1 g stall speed criteria in icing is an option to reduce approach speeds and landing distances in icing conditions.

From: NTSB
To: FAA
Date: 9/10/2008
Response: On April 26, 2007, the FAA published a notice of proposed rulemaking (NPRM) for the activation of the ice protection system (IPS) in Part 25 airplanes. The NPRM proposes to require IPS activation as soon as the airplane enters icing conditions. The NPRM also proposes that after the initial IPS activation, (1) the IPS operate continuously, (2) the airplane be equipped with a system that automatically cycles the IPS, or (3) an ice detection system be provided to alert the flightcrew each time the IPS must be cycled. For several years, the FAA has been considering a change to the Part 23 regulations concerning icing issues, including the method and timing of the IPS activation. The FAA indicated that in the interim, manufacturers of Part 23 airplanes have complied with Advisory Circular (AC) 23.1419-2C, which recommends that deicing boots be operated at the first sign of icing and in an appropriate continuous mode. The Safety Board is encouraged by the issuance of the NPRM, and on July 23, 2007, provided comments to the Docket for this rulemaking. The NPRM proposes actions for Part 25 airplanes that are responsive to Safety Recommendations A-07-14 and -15. Although the Board is concerned that the FAA has not yet initiated any rulemaking for Part 23 airplanes, AC 23.1419-2C addresses the regulatory changes recommended. Pending timely issuance of the final rule for the NPRM, and issuance of regulations for Part 23 airplanes, Safety Recommendations A-07-14 and -15 are classified OPEN -- ACCEPTABLE 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: This safety recommendation supersedes A-98-91. The recommendation is the same as A-98-91 except that it was limited to turbopropeller-driven airplanes in which ice bridging is not a concern, and this recommendation expands the applicability to all pneumatic deice boot-equipped airplanes. In our previous responses to A-98-91, we provided the Board with details on proposed Parts 25 and 121 rule changes that address the activation of airframe ice protection systems. The proposed rules will not distinguish the type of powerplant and therefore these rulemaking activities remain relevant to this new recommendation. We previously reported to the Board in our October 26, 2005 letter that the regulatory evaluations on these rule changes had been delayed due to the higher priority of other safety-related rulemaking activities. In March 2006, the FAA raised the priority of the Part 25 Activation of Ice Protection rulemaking. The notice of proposed rulemaking for the Part 25 Activation of Ice Protection was published on April 26, 2007 and a copy is enclosed. The proposed Part 25 rule would require, after the initial activation of the ice protection system, that: ·The ice protection system operate continuously, or; ·The airplane be equipped with a system that automatically cycles the ice protection system, or; ·An ice detection system be provided to alert the flightcrew each time the ice protection system must be cycled. As we stated in our October 26, 2005 letter the FAA is considering an icing regulation change to Part 23 that will address the method and timing of boot activation, in addition to other icing related issues that affect Part 23 airplanes. In the interim, manufacturers of Part 23 airplanes have been following the guidance in Advisory Circular 23.1419-2C, which recommends that deicing boots be operated at the first sign of icing and in an appropriate continuous mode. The recommendations apply to all airplanes with pneumatic deicing boots. The FAA believes this action should not be taken on airplanes without modern boots due to the potential for ice bridging. Modern boots are defined as those that use small diameter tubes (up to 1.75 inches), operated at nominal pressures of at least 15 psig by excess bleed air from a turbine engine, and rapid inflation and deflation.

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.