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

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: Ice formation on aircraft can disrupt the smooth flow of air over the wings and prevent the aircraft from taking off or decrease the pilot's ability to maintain control of the aircraft. Taxi and landing operations can also be risky in winter weather. Despite a variety of technologies designed to prevent ice from forming on planes, as well as persistent efforts by the Federal Aviation Administration (FAA) and other stakeholders to mitigate icing risks, icing remains a serious concern. As part of an ongoing review, this statement provides preliminary information on (1) the extent to which large commercial airplanes have experienced accidents and incidents related to icing and contaminated runways, (2) the efforts of FAA and aviation stakeholders to improve safety in icing and winter weather operating conditions, and (3) the challenges that continue to affect aviation safety in icing and winter weather operating conditions. GAO analyzed data obtained from FAA, the National Transportation Safety Board (NTSB), the National Aeronautics and Space Administration (NASA), and others. GAO conducted data reliability testing and determined that the data used in this report were sufficiently reliable for our purposes. Further, GAO obtained information from senior FAA and NTSB officials, representatives of the Flight Safety Foundation, and representatives of some key aviation industry stakeholder organizations. GAO provided a draft of this statement to FAA, NTSB, and NASA and incorporated their comments where appropriate.
section_title: What GAO Found
paragraphs: 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 due to snow or ice on runways. However, FAA and others recognize that incidents are potential precursors to accidents and the many reported icing incidents suggest that these airplanes face ongoing risks from icing. For example, FAA and NASA databases contain information on over 600 icing-related incidents involving large commercial airplanes. FAA and other aviation stakeholders have undertaken many efforts to improve safety in icing conditions. For example, in 1997, FAA issued a multiyear plan for improving the safety of aircraft operating in icing conditions and has since made progress on the objectives specified in its plan by issuing regulations, airworthiness directives, and voluntary guidance, among other initiatives. Other government entities that have taken steps to increase aviation safety in icing conditions include NTSB, which has issued numerous recommendations as a result of its aviation accident investigations, and NASA, which has contributed to icing-related research. The private sector has deployed various technologies on aircraft, such as wing deicers, and operated ground deicing and runway clearing programs at airports. GAO identified challenges related to winter weather aviation operations that, if addressed by ongoing or planned efforts, could improve 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; (3) ensuring that pilot training is thorough and realistic; (4) ensuring the collection and distribution of accurate weather information; and (5) developing a more integrated approach to effectively manage winter operations.

section_title: Letter
paragraphs: Thank you for the opportunity to testify today on issues related to aircraft  icing and conducting aviation operations on contaminated runways. Icing  can be a significant hazard for aviation operations of all types, including  commercial flights, no matter the season of the year. As shown in figure 1,  when there is ice on an aircraft’s wings, it can disrupt the smooth flow of  air over the wings and prevent the aircraft from safely taking off or  decrease the pilot’s ability to control the aircraft in flight. Depending on  the location of the ice, the shape of the wing, and the phase of flight, even  small, almost imperceptible amounts of ice can have a significant  detrimental effect. Despite a variety of technologies designed to prevent  ice from forming on planes or to remove ice that has formed, as well as  persistent efforts by the Federal Aviation Administration (FAA) and other  stakeholders to mitigate icing risks, icing remains a concern. Furthermore,  runways that have not been cleared of snow or ice can be hazardously  slick for planes during takeoff and landing.
Based on an ongoing review for this Subcommittee, as well as for the  Senate Aviation Subcommittee and Senator Charles Schumer, my  testimony today discusses preliminary information on (1) the extent to  which large commercial airplanes have experienced accidents and  incidents related to icing and contaminated runways, (2) the efforts of  FAA and other aviation stakeholders to improve safety in icing and winter  weather operating conditions, and (3) the challenges that continue to  affect aviation safety in icing and winter weather operating conditions. My  statement is based on our analyses of data related to icing obtained from  FAA, the National Transportation Safety Board (NTSB), the National  Aeronautics and Space Administration (NASA), and others. It also includes  updates from FAA of information published in our related reports. It  reflects our discussions with senior FAA, NTSB, NASA, and National  Oceanic and Atmospheric Administration (NOAA) officials and  representatives from the Flight Safety Foundation and several aviation  industry organizations. As part of our ongoing review, we performed this  work from August 2009 to February 2010 in accordance with generally  accepted government auditing standards. Those standards require that we  plan and perform the audit to obtain sufficient, appropriate evidence to  provide a reasonable basis for our findings and conclusions based on our  review objectives. We believe that the evidence obtained provides a  reasonable basis for our findings and conclusions based on our audit  objectives. Further, we conducted data reliability testing and determined  that the data used in this report were sufficiently reliable for our purposes.  We provided a draft of this testimony to FAA, NTSB, and NASA officials to  obtain their comments. In response, FAA, NTSB, and NASA provided  additional information that we incorporated where appropriate.
subsections: section_title: 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
paragraphs: 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.
section_title: FAA and Other Aviation Stakeholders Have Undertaken a Variety of Efforts Aimed at Improving Safety in Icing/Winter Weather Conditions
subsections: section_title: FAA Adopted a Plan to Increase Safety in Icing Conditions and Has Taken Other Actions to Improve Safety in Winter Weather
paragraphs: 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.
section_title: Other Stakeholders Support and Augment FAA Efforts to Increase Safety in Winter Weather/Icing Conditions
paragraphs: 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.
section_title: Continued Attention to Regulation, Training, and Coordination Issues Could Further Mitigate the Risks of Winter Weather Operations
paragraphs: 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.
section_title: GAO Contact and Staff Acknowledgments
paragraphs: 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.
section_title: Appendix I: FAA’s Funding to the Airport Improvement Program for Icing-Related Projects, 1999—2009, by State and City
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