subroutine azdist(MyGrid,HisGrid,utch,nAz,nEl,nDmiles,nDkm,
     +  nHotAz,nHotABetter)

      character*6 MyGrid,HisGrid,mygrid0,hisgrid0
      real*8 utch,utch0
      logical HotABetter,IamEast
      real eltab(22),daztab(22)
      data eltab/18.,15.,13.,11.,9.,8.,7.,6.,5.3,4.7,4.,3.3,2.7,
     +  2.,1.5,1.,0.8,0.6,0.4,0.2,0.0,0.0/
      data daztab/21.,18.,16.,15.,14.,13.,12.,11.,10.7,10.3,10.,
     +  10.,10.,10.,10.,10.,10.,9.,9.,9.,8.,8./
      data mygrid0/"      "/,hisgrid0/"      "/,utch0/-999.d0/
      save

      if(MyGrid.eq.HisGrid) then
         naz=0
         nel=0
         ndmiles=0
         ndkm=0
         nhotaz=0
         nhotabetter=1
         go to 999
      endif

      if(mygrid.eq.mygrid0 .and. hisgrid.eq.hisgrid0 .and.
     +  abs(utch-utch0).lt.0.1666667d0) go to 900
      utch0=utch
      mygrid0=mygrid
      hisgrid0=hisgrid
      utchours=utch

      if(MyGrid(5:5).eq.' ') MyGrid(5:5)='m'
      if(MyGrid(6:6).eq.' ') MyGrid(6:6)='m'
      if(HisGrid(5:5).eq.' ') HisGrid(5:5)='m'
      if(HisGrid(6:6).eq.' ') HisGrid(6:6)='m'

      if(MyGrid.eq.HisGrid) then
         Az=0.
         Dmiles=0.
         Dkm=0.0
         El=0.
         HotA=0.
         HotB=0.
         HotABetter=.true.
         go to 900
      endif

      call grid2deg(MyGrid,dlong1,dlat1)
      call grid2deg(HisGrid,dlong2,dlat2)
      call geodist(dlat1,dlong1,dlat2,dlong2,Az,Baz,Dkm)

      ndkm=Dkm/100
      j=ndkm-4
      if(j.lt.1) j=1
      if(j.gt.21)j=21
      if(Dkm.lt.500.0) then
        El=18.0
      else
        u=(Dkm-100.0*ndkm)/100.0
        El=(1.0-u)*eltab(j) + u*eltab(j+1)
      endif

      daz=daztab(j) + u * (daztab(j+1)-daztab(j))
      Dmiles=Dkm/1.609344

      tmid=mod(UTChours-0.5*(dlong1+dlong2)/15.0+48.0,24.0)
      IamEast=.false.
      if(dlong1.lt.dlong2) IamEast=.true.
      if(dlong1.eq.dlong2 .and. dlat1.gt.dlat2) IamEast=.false.
      azEast=baz
      if(IamEast) azEast=az
      if((azEast.ge.45.0 .and. azEast.lt.135.0) .or.
     +    (azEast.ge.225.0 .and. azEast.lt.315.0)) then
C  The path will be taken as "east-west".
         HotABetter=.true.
         if(abs(tmid-6.0).lt.6.0) HotABetter=.false.
         if((dlat1+dlat2)/2.0 .lt. 0.0) HotABetter=.not.HotABetter
      else
C  The path will be taken as "north-south".
         HotABetter=.false.
         if(abs(tmid-12.0).lt.6.0) HotABetter=.true.
      endif
      if(IamEast) then
         HotA = Az - daz
         HotB = Az + daz
      else
         HotA = Az + daz
         HotB = Az - daz
      endif
      if(HotA.lt.0.0)   HotA=HotA+360.0
      if(HotA.gt.360.0) HotA=HotA-360.0
      if(HotB.lt.0.0)   HotB=HotB+360.0
      if(HotB.gt.360.0) HotB=HotB-360.0

 900  continue
      naz=nint(Az)
      nel=nint(el)
      nDmiles=nint(Dmiles)
      nDkm=nint(Dkm)
      nHotAz=nint(HotB)
      nHotABetter=0
      if(HotABetter) then
         nHotAz=nint(HotA)
         nHotABetter=1
      endif

 999  return
      end