PB98-910404 ‘I NTSB/AAR-98/04 DCA97MA017 NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. 20594 AIRCRAFT ACCIDENT REPORT IN-FLIGHT ICING ENCOUNTER AND UNCONTROLLED COLLISION WITH TERRAIN COMAIR FLIGHT 3272 EMBRAER EMB-120RT, N265CA MONROE, MICHIGAN JANUARY 9, 1997 6997A/B/C The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, railroad, highway, marine, pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress through the Independent Safety Board Act of 1974 to investigate transportation accidents, determine the probable causes of the accidents, issue safety recommendations, study transportation safety issues, and evaluate the safety effectiveness of government agencies involved in transportation. The Safety Board makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and statistical reviews. 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Safety issues in the report focused on procedures for the use of ice protection systems, airspeed and flap configuration information, stall warning/protection system capabilities, operation of the autopilot in icing conditions, aircraft icing certification requirements, and icing-related research. Safety recommendations concerning these issues were addressed to the Federal Aviation Administration and the National Aeronautics and Space Administration. CONTENTS EXECUTIVE SUMMARY.......................................................................................................vii SELECTED ACRONYMS, ABBREVIATIONS, AND DEFINITIONS……………………..viii 1. FACTUAL INFORMATION .................................................................................................................................... 1 1.1 History of Flight.................................................................................................................................................... 1 1.2 Injuries to Persons................................................................................................................................................. 6 1.3 Damage to Airplane .............................................................................................................................................. 6 1.4 Other Damage ....................................................................................................................................................... 6 1.5 Personnel Information........................................................................................................................................... 6 1.5.1 Comair Flight 3272 Captain ...................................................................................................................... 6 1.5.2 Comair Flight 3272 First Officer............................................................................................................... 7 1.5.3 Controller at the Feeder Approach Control Position.............................................................................. 8 1.5.4 Controller at the Final Approach Control Position................................................................................. 8 1.6 Airplane Information............................................................................................................................................. 9 1.6.1 EMB-120 Icing Certification/Controllability History ........................................................................... 12 1.6.1.1 EMB-120 Icing Certification ............................................................................................................... 12 1.6.1.1.1 Current Icing Certification Guidance for Transport-Category Aircraft ........................................ 14 1.6.1.1.2 Draft Aviation Rulemaking Advisory Committee Icing Certification Guidance for Transport- Category Aircraft .......................................................................................................................................... 17 1.6.1.2 EMB-120 Severe Icing (Supercooled Large Droplet) Controllability Tests........................................ 18 1.6.2 Pilot Reports Regarding EMB-120 Flight Characteristics and Operations ....................................... 20 1.6.2.1 EMB-120 Airspeed Information (Pilot Interviews/Comair’s Manuals)............................................. 21 1.6.3 EMB-120 Systems ..................................................................................................................................... 25 1.6.3.1 Stall Warning/Protection System......................................................................................................... 26 1.6.3.2 Autopilot System Information ............................................................................................................. 27 1.6.3.3 Ground Proximity Warning System .................................................................................................... 32 1.6.3.4 Ice Protection System Information ...................................................................................................... 34 1.6.3.4.1 Ice Protection System Maintenance History.................................................................................. 36 1.6.3.4.2 Ice Protection Failure Warning System—Functional Test............................................................ 37 1.7 Meteorological Information ................................................................................................................................ 38 1.7.1 Weather Synopsis..................................................................................................................................... 38 1.7.2 Weather Advisories and Observations ................................................................................................... 38 1.7.3 Weather Information Provided to the Flightcrew by Comair.............................................................. 40 1.7.4 Pilot Reports and Witness Descriptions of Weather Conditions.......................................................... 41 1.7.5 Information from Weather Radar and Satellite Data........................................................................... 45 1.7.6 Information from the National Center for Atmospheric Research Mesoscale Meteorological Study46 1.8 Aids to Navigation .............................................................................................................................................. 48 iii 1.9 Communications ................................................................................................................................................. 48 1.10 Airport Information........................................................................................................................................... 48 1.11 Flight Recorders................................................................................................................................................ 49 1.11.1 Cockpit Voice Recorder ......................................................................................................................... 49 1.11.2 Flight Data Recorder .............................................................................................................................. 49 1.11.2.1 FDR Anomalies and History............................................................................................................... 53 1.12 Wreckage and Impact Information ................................................................................................................... 56 1.12.1 Engines and Propellers........................................................................................................................... 56 1.12.2 Deicing/Anti-icing Equipment ............................................................................................................... 57 1.13 Medical and Pathological Information ............................................................................................................. 59 1.14 Fire .................................................................................................................................................................... 59 1.15 Survival Aspects ............................................................................................................................................... 60 1.16 Tests and Research...........................................................................................................................................