Not saying this is 'good' code, just that it looks like it works.

Code:
on *:text:!metar *:#:{
  if ($2 isalnum) { 
    window -a $chan
    set %vatsim.ID $lower($2)
    set %vatsim.Chan #
    sockopen vatsim metar.vatsim.net 80
  }
}

on *:sockopen:vatsim: {
  sockwrite -n $sockname GET /metar.php?id= $+ %vatsim.ID HTTP/1.0
  sockwrite -n $sockname User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)
  sockwrite -n $sockname Host: metar.vatsim.net
  ;sockwrite -n $sockname max-age: 0
  sockwrite -n $sockname Accept-Language: en-us
  sockwrite -n $sockname Accept: */*
  sockwrite -n $sockname
}

on *:sockread:vatsim: {
  if ($sockerr) { echo -a Sock $sockname Error: $sockerr | halt }
  var %test
  sockread 4000 %test
  echo -s $scriptline sockread text: %test
  if (%vatsim.ID $+ * iswm %test) { describe %vatsim.Chan respond: %test | sockclose $sockname }
}