AIAA 2016-4364 AIAA AVIATION Forum 13-17 June 2016, Washington, D.C. 16th AIAA Aviation Technology, Integration, and Operations Conference
Slippery When Wet: The Case for More Conservative Wet Runway Braking Coefficient Models
John J. O’Callaghan1 National Transportation Safety Board, Washington, D.C., 20594
Over the past eight years, the NTSB has led or participated in the investigation of a number of runway overrun accidents and incidents that occurred after the airplanes involved landed on wet runways. An analysis of the airplane stopping performance during
these events indicates that the wheel braking friction coefficient (B) achieved during the landing roll was significantly less than the B predicted by industry-accepted models, and less than the B assumed in the wet-runway landing distance advisory data provided in the manufacturers’ Airplane Flight Manuals. In recognition of this problem, the Federal Aviation Administration has issued a safety alert to operators warning them that the advisory data for wet runway landings may not provide a safe stopping margin under all conditions, and tasked an Aviation Rulemaking Advisory Committee with reviewing the wet runway stopping performance requirements contained in the 14 Code of Federal
Regulations (CFR) Part 25 airworthiness standards and guidance (the B that can be assumed on a wet runway during an aborted takeoff is specified by 14 CFR 25.109, and the 25.109 model has been proposed for computing landing distances on a wet runway). This paper presents six wet runway landing overrun events (all involving turbojet
airplanes) and compares the B achieved by the airplane in each event with the B predicted by several models and inherent in advisory data. The results indicate that
current models and advisory data can significantly overestimate the B achievable on wet runways (and therefore underestimate the required runway length for landing on these runways). Consequently, these events underscore the need for more conservative models of
B, and more conservative use of existing advisory data and models in the meantime.
Nomenclature Acronyms
AA American Airlines AC Advisory Circular AFM Airplane Flight Manual AIR SAE Aerospace Information Report AMC Acceptable Means of Compliance (EASA) AMJ Advisory Material Joint (Europe)
Downloaded by BOEING COMPANY on March 17, 2017 | http://arc.aiaa.org DOI: 10.2514/6.2016-4364 ARAC Aviation Rulemaking Advisory Committee ASOS Airport Surface Observation System ATIS Automatic Terminal Information Service BA Bombardier Aerospace BCAR British Civil Aviation Requirements CFME Continuous Friction Measurement Equipment CFR Code of Federal Regulations CG Center of Gravity CMB Combined model CS Certification Specification (EASA) CVR Cockpit Voice Recorder CYMX Montreal Mirabel Airport, Montreal, Canada CYOW Ottawa/MacDonald-Cartier International Airport, Ottawa, Ontario
1 National Resource Specialist – Aircraft Performance, Office of Research and Engineering, RE-60, Member AIAA. 1 American Institute of Aeronautics and Astronautics
This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.
DFT Neubert Aero Corporation Dynamic Friction Tester CFME device EASA European Aviation Safety Agency EPB Emergency / Parking Brake ESDU Engineering Science Data Unit EU OPS European operational regulation(s) FAA Federal Aviation Administration FDR Flight Data Recorder FTHWG Flight Test Harmonization Working Group ICAO International Civil Aviation Organization ILS Instrument Landing System IMC Instrument Meteorological Conditions JAR European Joint Aviation Regulations JCAA Civil Aviation Authority of Jamaica KCXO Lone Star Executive Airport, Conroe, Texas KMDW Chicago Midway Airport, Chicago, Illinois KOWA Owatonna Degner Regional Airport, Owatonna, Minnesota KSGR Sugar Land Regional Airport, Sugar Land, Texas MAINT LEVEL AC 150/5320-12C Maintenance Planning Friction Level MIN LEVEL AC 150/5320-12C Minimum Friction Level MKJP Norman Manley International Airport, Kingston, Jamaica MM Mu meter CFME device NAC Neubert Aero Corporation NASA National Aeronautics and Space Administration NEW LEVEL AC 150/5320-12C New Design/Construction Friction Level NRC National Resource Council of Canada NTSB National Transportation Safety Board RCAM Runway Condition Assessment Matrix REP LEVEL Average of AC 150/5320-12C MIN LEVEL and MAINT LEVEL RNAV Area Navigation (instrument approach) SAE Society of Automotive Engineers SAFO Safety Alert For Operators SFT Airport Surface Friction Tester CFME device SW Southwest Airlines TALPA ARC Takeoff/Landing Performance Assessment Aviation Rulemaking Committee TAPHC Transport Airplane Performance and Handling Characteristics TC Transport Canada TSB Transportation Safety Board of Canada TTI Texas Transportation Institute UE United Express Airlines USA United States of America UTC Universal Coordinated Time Downloaded by BOEING COMPANY on March 17, 2017 | http://arc.aiaa.org DOI: 10.2514/6.2016-4364 WOW Weight On Wheels
English symbols
d Average water depth above the top of the runway macrotexture Longitudinal reaction force at nose gear Longitudinal reaction force at main gear Force along body x-axis Force along body z-axis I Rainfall intensity k Factor on to account for installation and undercarriage effects = ( | : ) / ( | . ) = ( | : ) / ( | . ) L Runway drainage path-length (distance from runway centerline) Moment about body y-axis 2 American Institute of Aeronautics and Astronautics