This is what I do to convert the FS9 longitude and latitude coordinates into the decimal (FSX) format. I do it in MS Excel which doesn't understand '-0' which creates a problem because some of the airports are close to longitude 0 and or latitude 0. That is why particular attention is paid to the '-'.
FS9ICAO="06AZ"
FS9Longitude="N35 47.50"
FS9Latitude="W110 25.40"
FS9Nhemisphere=LEFT(FS9Longitude,1)
FS9LongDegrees=MID(FS9Longitude,2,SEARCH(" ",FS9Longitude,1)-2)
FS9LongMinutes=MID(FS9Longitude,SEARCH(" ",FS9Longitude,1)+1,LEN(FS9Longitude)-SEARCH(" ",FS9Longitude,1))
FS9DecimalLongitude=ROUND(IF(FS9Nhemisphere="S","-"&FS9LongDegrees+(FS9LongMinutes/60),FS9LongDegrees+(FS9LongMinutes/60)),8)
FS9Ehemisphere=LEFT(FS9Latitude,1)
FS9LatDegrees=MID(FS9Latitude,2,SEARCH(" ",FS9Latitude,1)-2)
FS9LatMinutes=MID(FS9Latitude,SEARCH(" ",FS9Latitude,1)+1,LEN(FS9Latitude)-SEARCH(" ",FS9Latitude,1))
FS9DecimalLatitude=ROUND(IF(FS9Ehemisphere="W","-"&FS9LatDegrees+(FS9LatMinutes/60),FS9LatDegrees+(FS9LatMinutes/60)),8)
The result is that:
FS9DecimalLongitude=35.79166667
FS9DecimalLatitude=-110.42333333
I can't give you a converted list for all the airports because I only bothered to calculate the decimal coordinates for those FS9 ICAO codes that don't appear in the FSX list (1,104 of them). This was so that I could figure out what the new ICAO codes are in FSX or whether the airport has 'disappeared' from the face of the earth (126 of them have disappeared in FSX).