Aviation Safety: Preliminary Information on Aircraft Icing and Winter Operations
Released: 2010-02-24T00:00:00

Letter

Although Large Commercial Airplanes Have Experienced Few Icing-Related Accidents since 1998, the Many Reported Icing Incidents Suggest that Icing Is an Ongoing Risk to Aviation Safety

According to NTSB’s aviation accident database, from 1998 to 2009 one large commercial airplane was involved in a nonfatal accident after encountering icing conditions during flight and five large commercial airplanes were involved in nonfatal accidents related to snow or ice on runways. Although there have been few accidents, FAA and others recognize that incidents are potential precursors to accidents. Data on hundreds of incidents that occurred during this period reveal that icing and contaminated runways pose substantial risk to aviation safety. FAA’s database of incidents includes 200 icing-related incidents involving large commercial airplanes that occurred from 1998 through 2007. These data covered a broad set of events, such as the collision of two airplanes at an ice-covered gate, and an airplane that hit the right main gear against the runway and scraped the left wing down the runway for about 63 feet while attempting to land with ice accumulation on the aircraft. During this same time period, NASA’s Aviation Safety Reporting System (ASRS) received over 600 icing and winter weather-related incident involving large commercial airplanes. These incidents reveal a variety of safety issues such as runways contaminated by snow or ice, ground deicing problems, and in-flight icing encounters. This suggests that risks from icing and other winter weather operating conditions may be greater than indicated by NTSB’s accident database and by FAA’s incident database. FAA officials point out that there is no defined reporting threshold for ASRS reports and because they are developed from personal narrative, they can be subjective. However, these officials agree that the ASRS events must be thoroughly reviewed and evaluated for content to determine the relevancy to icing and the extent and severity of the safety issue. The contents of the ASRS data system also demonstrate the importance of aggregating data from all available sources to understand a safety concern. See table 1 for the number of icing and winter weather-related incident reports from ASRS for large commercial airplanes.

While this testimony focuses on large commercial airplanes, I would like to note that from 1998 to 2007, small commercial airplanes and noncommercial airplanes experienced more icing-related accidents and fatalities than did large commercial airplanes, as shown in table 2. This is largely because, compared to large commercial airplanes, small commercial airplanes and noncommercial airplanes (1) operate at lower altitudes that have more frequent icing conditions, (2) have a higher icing collection efficiency due to their smaller scale, (3) are more greatly impacted by ice as a result of their smaller scale, (4) tend to have deicing equipment rather than fully evaporative anti-icing equipment, (5) may not have ice protection systems that are certified, nor are they required to be, because the airplane is not approved for flight in known icing conditions, and (6) may not have ice protections systems installed.

FAA and Other Aviation Stakeholders Have Undertaken a Variety of Efforts Aimed at Improving Safety in Icing/Winter Weather Conditions

FAA Adopted a Plan to Increase Safety in Icing Conditions and Has Taken Other Actions to Improve Safety in Winter Weather

Following the 1994 fatal crash of American Eagle Flight 4184 in Roselawn, Indiana, FAA issued a multiyear plan in 1997for improving the safety of aircraft operating in icing conditions and created a steering committee to monitor the progress of the planned activities. Over the last decade, FAA made progress on the implementation of the objectives specified in its multiyear plan by issuing or amending regulations, airworthiness directives (ADs), and voluntary guidance to provide icing-related safety oversight. For example, FAA issued three final rules on icing: in August 2007, a rule introduced new airworthiness standards to establish comprehensive requirements for the performance and handling characteristics of transport category airplanes in icing conditions; in August 2009, a rule required a means to ensure timely activation of the ice protection system on transport category airplanes; and in December 2009, a rule required pilots to ensure that the wings of their aircraft are free of polished frost.

FAA has also proposed an icing-related rule in November 2009, on which the public comment period closed February 22, 2010; this rule would require the timely activation of ice protection equipment on commercial aircraft during icing conditions and weather conditions conducive to ice formation on the aircraft. In addition, FAA is developing a proposed rule to amend its standards for transport category airplanes to address supercooled large drop icing, which is outside the range of icing conditions covered by the current standards. Since 1997, FAA has issued over 100 ADs to address icing safety issues involving more than 50 specific types of aircraft, including ADs that required the installation of new software on certain aircraft and another that required operators and manufactures to install placards displaying procedures for use of an anti- icing switch on certain aircraft. Additionally, FAA has issued bulletins and alerts to operators emphasizing icing safety issues. As part of our ongoing review, we will conduct a more comprehensive evaluation of FAA’s progress on the implementation of the objectives specified in its multiyear in-flight icing plan. Among other things, we will also analyze the results of FAA’s surveillance activities related to monitoring air carriers’ compliance with existing regulations and ADs.

FAA also provided funding for a variety of icing-related purposes. For example, FAA has supported NASA research related to severe icing conditions and the National Center for Atmospheric Research (NCAR) research related to weather and aircraft icing. Furthermore, FAA has provided almost $200 million to airports through the Airport Improvement Program (AIP) to construct deicing facilities and to acquire aircraft deicing equipment from 1999 to 2009. See appendix I for a detailed listing of AIP icing-related funding by state, city, and year.

Runway safety is a key concern for aviation safety and especially critical during winter weather operations. For example, in December 2005, a passenger jet landed on a snowy runway at Chicago’s Midway Airport, rolled through an airport perimeter fence onto an adjacent roadway, and struck an automobile, killing a child and injuring 4 other occupants of the automobile and 18 airline passengers. According to the Flight Safety Foundation, from 1995 through 2008, 30 percent of global aviation accidents were runway-related and “ineffective braking/runway contamination” is the fourth largest causal factor in runway excursions that occur during landing. In fiscal year 2000, FAA’s Office of Airport Safety and Standards initiated a program, which includes making funds available to airports through AIP, to accelerate improvements in runway safety areas at commercial service airports that did not meet FAA design standards.

EMAS uses materials of closely controlled strength and density placed at the end of the runway to stop or greatly slow an aircraft that overruns the runway. According to FAA, the best material found to date is a lightweight crushable concrete.

2010. To date there have been five successful EMAS captures of overrunning aircraft.

Other Stakeholders Support and Augment FAA Efforts to Increase Safety in Winter Weather/Icing Conditions

Government and industry stakeholders, external to FAA, also contribute to the effort to increase aviation safety in winter weather/icing conditions. For example, NTSB investigates and reports on civil aviation accidents and issues safety recommendations to FAA and others, some of which it deems most critical and places on a list of “Most Wanted” recommendations. Since 1996, NTSB has issued 82 recommendations to FAA aimed at reducing risks from in-flight structural icing, engine and aircraft component icing, runway condition and contamination, ground icing, and winter weather operations. NTSB’s icing-related recommendations to FAA have called for FAA to, among other things, strengthen its requirements for certifying aircraft for flying in icing conditions, sponsor the development of weather forecasts that define locations with icing conditions, and enhance its training requirements for pilots. NTSB has closed 39 of these recommendations (48 percent) as having been implemented by FAA, and has classified another 25 (30 percent) as FAA having made acceptable progress. This combined 78 percent acceptance rate is similar to the rate for all of NTSB’s aviation recommendations.

For more than 30 years, NASA has conducted and sponsored fundamental and applied research related to icing. The research addresses icing causes, effects, and mitigations. For instance, NASA has conducted extensive research to characterize and simulate supercooled large drop icing conditions to inform a pending FAA rule related to the topic. NASA participated in research activities, partially funded by FAA, that developed additional knowledge and strategies which allowed forecasters to more precisely locate supercooled large drop icing conditions. Furthermore, NASA has an icing program, focused generally on research related to the effects of in-flight icing on airframes and engines for many types of flight vehicles. NASA has developed icing simulation capabilities that allow researchers, manufacturers, and certification authorities to better understand the growth and effects of ice on aircraft surfaces. NASA also produced a set of training materials for pilots operating in winter weather conditions. In recent years, NASA’s funding decreased significantly, limiting the capability of its icing research program.

NOAA, the National Weather Service (NWS), and NCAR have efforts directed and funded by FAA related to predicting the location and severity of icing occurrences. NWS operates icing prediction systems and NCAR conducts research to determine more efficient methods to complete this task. For example, in 2006, NCAR introduced a new Web-based icing forecast tool that allows meteorologists and airline dispatchers to warn pilots about icing hazards up to 12 hours in advance. NCAR developed this tool using FAA funding and NWS facilitates the operation of the new icing forecasting tool. NWS also posts on the agency’s Web site maps of current icing conditions, pilot reports, forecasts, and freezing level graphics.

The private sector has also contributed to efforts to prevent accidents and incidents related to icing and winter weather conditions. For example, as shown in figure 2, aircraft manufacturers have deployed various technologies such as wing deicers, anti-icing systems, and heated wings.

In addition, airports operate ground deicing and runway clearing programs that help ensure clean wings (see fig. 3) and runways. While critical to safe, efficient winter operations, these programs involve treating aircraft and airport pavement with millions of pounds of deicing and anti-icing compounds annually. According to the Environmental Protection Agency, these compounds contain chemicals that can harm the environment. Some airports can control deicing pollution by capturing the fluids used to deice aircraft using technologies such as AIP-funded deicing pads, where aircraft are sprayed with deicing fluids before takeoff and the fluids are captured and treated; drainage collection systems; or vacuum-equipped vehicles. Third-party contractors, rather than individual air carriers, are increasingly performing deicing operations at commercial airports. FAA does not currently have a process to directly oversee these third-party contractors but indicates that it has one under development.

Continued Attention to Regulation, Training, and Coordination Issues Could Further Mitigate the Risks of Winter Weather Operations

While FAA and others are undertaking efforts to mitigate the risks of aircraft icing and winter weather operations, through our interviews and discussions with government and industry stakeholders, we have identified challenges related to these risks that, if addressed by ongoing or planned efforts, could improve aviation safety. These challenges include (1) improving the timeliness of FAA’s winter weather rulemaking efforts, (2) ensuring the availability of adequate resources for icing-related research and development (R&D), (3) ensuring that pilot training is thorough, relevant, and realistic, (4) ensuring the collection and distribution of timely and accurate weather information, and (5) developing a more integrated approach to effectively manage winter operations.

Improving the timeliness of FAA’s winter weather rulemaking efforts. FAA’s rulemaking, like that of other federal agencies, is a complicated, multistep process that can take many years. Nonetheless, NTSB, FAA, and we have previously expressed concerns about the efficiency and timeliness of FAA’s rulemaking efforts. In 2001, we reported that a major reform effort begun by FAA in 1998 did not solve long-standing problems with its rulemaking process, as indicated both by the lack of improvement in the time required to complete the rulemaking process and by the agency’s inability to consistently meet the time frames imposed by statute or its own guidance. External pressures—such as highly-publicized accidents, recommendations by NTSB, and congressional mandates—as well as internal pressures, such as changes in management’s emphasis continued to add to and shift the agency’s priorities. For some rules, difficult policy issues continued to remain unresolved late in the process. The 2001 report contained 10 recommendations designed to improve the efficiency of FAA’s rulemaking through, among other things, (1) more timely and effective participation in decision-making and prioritization; (2) more effective use of information management systems to monitor and improve the process; and (3) the implementation of human capital strategies to measure, evaluate, and provide performance incentives for participants in the process. FAA implemented 8 of the 10 recommendations.

NTSB’s February 2010 update on the status of its Most Wanted recommendations related to icing characterized FAA’s related rulemaking efforts as “unacceptably slow.” In December 2009, at FAA’s International Runway Safety Summit, NTSB’s Chairman commented, “How do safety improvements end up taking 10 years to deliver? They get delayed one day at a time . . . and every one of those days may be the day when a preventable accident occurs as the result of something we were ‘just about ready to fix.’” In particular, NTSB has expressed concern about the pace of FAA’s rulemaking project to amend its standards for transport category airplanes to address supercooled large drop icing, which is outside the range of icing conditions covered by the current standards. FAA began this rulemaking effort in 1997 in response to a recommendation made by NTSB the prior year, and the agency currently expects to issue its proposed rule in July 2010 and the final rule in January 2012. However, until the notice of proposed rulemaking is published and the close of the comment period is known, it will be unclear as to when the final rule will be issued. Much of the time on this rulemaking effort has been devoted to research and analysis aimed at understanding the atmospheric conditions that lead to supercooled large drop icing.

In 2009, FAA completed an internal review of its rulemaking process that concluded that several of the concerns from 1998 that led to the agency’s major reform effort remain issues, including: inadequate early involvement of key stakeholders; inadequate early resolution of issues; inadequate selection and training of personnel involved in rulemaking; and inefficient quality guidance.

According to FAA’s manager for aircraft and airport rules, the agency is taking steps to implement recommendations made by the internal review, such as revising the rulemaking project record form and enhancing training for staff involved in rulemaking. In addition, in October 2009, FAA tasked its Aviation Rulemaking Advisory Committee (ARAC) with reviewing its processes and making recommendations for improvement within a year. We believe these efforts have the potential to improve the efficiency of FAA’s rulemaking process. Recently, moreover, FAA has demonstrated a commitment to making progress on some high-priority rules that have languished for a long time. For example, FAA officials have said that they intend to expedite FAA’s rulemaking on pilot fatigue, which has been in process since 1992. The issue of insufficient rest emerged as a concern from NTSB’s investigation of the February 12, 2009, crash of Continental Connection/Colgan Air Flight 3407 near Buffalo, New York.

Moreover, a capacity for progress in rulemaking will be critical because, as we have reported to this Subcommittee in our recent reviews of the transition to the Next Generation Air Transportation System (NextGen), many of the procedures that are proposed to safely enhance the efficiency and capacity of the national airspace system to address current delays and congestion in the system and to accommodate forecasted increases in air traffic will be dependent on the timely development of rules and standards.

Ensuring the availability of adequate resources for icing-related R&D. NASA is a key source of R&D related to icing. The agency performs fundamental research related to icing in house and sponsors such research at universities and other organizations. According to NASA officials, possible areas for increased support for R&D that could be helpful include pilot training, supercooled large drop simulation (both experimental and computational), engine icing, and the effects of icing on future aircraft wing designs. However, the amount of NASA resources (including combined amounts of NASA’s budget and funding from FAA for aircraft icing R&D at NASA facilities) and staffing for icing research have declined significantly since fiscal year 2005, as shown in figure 4. According to NASA officials, there were several contributing factors to the decline in available resources including the fiscal constraints on the overall federal budget, a shift in the Administration’s priorities for NASA, as well as a restructuring within the NASA’s aeronautical programs to reflect the available resources and priorities. Because the outcomes of R&D are often required for the development of rules and standards, as well as for technological innovation, a decline in R&D resources can delay actions that would promote safe operation in icing conditions.

In June 2008, the FAA sponsored a symposium on fatigue management that provided an opportunity for subject matter experts to come together and discuss fatigue’s effects on flight crews, maintenance personnel, and air traffic controllers. NTSB believes that fatigue management plans may hold promise as an approach to dealing with fatigue in the aviation environment. However, NTSB considers fatigue management plans to be a complement to, not a substitute for, regulations to prevent fatigue.

GAO Contact and Staff Acknowledgments

For further information about this testimony, please contact Gerald Dillingham at (202) 512-2834. Individuals making key contributions to this testimony included Laurel Ball, Shareea Butler, Colin Fallon, David Goldstein, Brandon Haller, David Hooper, Joshua Ormond, and Sally Moino.

Appendix I: FAA’s Funding to the Airport Improvement Program for Icing-Related Projects, 1999—2009, by State and City

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