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CE 563 Airport Design

  Winds  are  a  large  factor  in  determining  runway  orientation  and  number  of  runways  

  Runway  should  be  oriented  with  prevailing  winds    The  smaller  the  aircraft,  the  more  it  is  affected  by  winds,  particularly  crosswinds  

  Crosswinds  are  a    often  contributing  factor  in  small  aircraft  accidents  

   AC  150/5300-­‐13,  Appendix  1    

  Headwind  (HW)   Wind  acting  towards  aircraft  head,  parallel  to  aircraft  longitudinal  axis  

  Tailwind  (TW)   Wind  acting  toward  aircraft  tail,  parallel  to  aircraft  longitudinal  axis  

  Crosswind    (XW)   Wind  acting  at  right-­‐angle  to  aircraft  

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HW TW

XW

XW

20 kts

θ

XW =Vw sin!XW = (20kts)sin60o

XW =17kts

HW =Vw cos!HW = (20kts)cos60o

HW =10kts

Crosswind Component Headwind Component

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  “When  a  runway  orientation  provides  less  than  95  percent  wind  coverage  for  any  aircraft  forecasted  to  use  the  airport  on  a  regular  basis,  a  crosswind  runway  is  recommended.”  

   -­‐AC  150/5300-­‐13,  Paragraph  203b  

Airport  Reference  Code   Allowable  Crosswind,  kts  A-­‐I,  B-­‐I   10.5  A-­‐II,  B-­‐II   13.0  A-­‐III,  B-­‐III,  C-­‐I  through  D-­‐III   16.0  A-­‐IV  through  D-­‐VI   20.0  

Source:  AC  150/5300-­‐13,  Paragraph  203b  

  Wind  coverage    Percent  of  time  when  crosswind  components  are  below  an  acceptable  velocity  

  Most  desirable  runway  orientation  maximizes  wind  coverage  and  minimizes  crosswinds  

  Desirable  wind  coverage  is  95  percent    May  be  situations  where  data  analysis  is  for  less  than  24  hours  per  day  of  operation  (eg.  no  night  traffic)  or  seasonal  

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  National  Oceanic  and  Atmospheric  Administration,  National  Climatic  Data  Center  (NCDC),  Asheville,  NC,  http://www.ncdc.noaa.gov/  

  Data  usually  available  for  hundreds  of  weather  stations  throughout  the  US  

  Data  should  be  in  the  proper  format    36  wind  quadrants    Usual  speed  groupings  

  What  if  there  is  no  data  for  the  proposed  site?  

Figure  A1-­‐2  Appendix  1  AC  150/5300-­‐13  

  Windrose    Concentric  circles,  each  represents  a  division  between  wind  speeds  

  Radial  lines,  directions    Each  segment  is  a  direction  and  velocity  corresponding  to  the  wind  data  

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Figure  A1-­‐3  Appendix  1  AC  150/5300-­‐13  

  Windrose    Each  speed  and  direction  is  converted  into  a  percentage  of  the  total  observations,  rounded  to  the  nearest  0.1%  and  placed  in  the  proper  segment  

  “+”  symbol  used  to  indicate  direction/speed  combinations  occurring  less  than  0.1%  of  the  time  

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  Crosswind  template    Three  parallel  lines  drawn  to  the  same  scale  as  the  windrose  

  Allowable  crosswind  determines  distance  from  the  centerline  to  the  outer  two  lines  

  Rotate  the  template  to  various  orientations  and  maximize  the  coverage  

  Easiest  to  add  outside  the  lines  and  subtract  from  100!  

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  Web-­‐based  wind  analysis  tool  at  http://airports-­‐gis.faa.gov/public/  

  Spreadsheet  tool