coordinates discrepancies in AFD'S

[Vavso]

I am finding that the lat and long coordinates in the AFD ( facility Directories) are different than in Airnav and other online sources these differences account for sometimes 100-200 yds off would anyone know why this is ? example

1)bridge ndb id ogy in facility directory shows as n40 34 09 w73 52 98 at airnav shows n40 34 05 w73 52 58

2) jfk airport in facility directory shows n40 38 39 w 73 46 74 in airnav shows n40 38 23 w 73 46 44

thanks vavso

 

[VNugget]

My guess is that they're based off different map projection types, and/or different reference parallels.

 

[DitchDriver]

1)bridge ndb id ogy
n40 34 09 w73 52 98 -- facility directory
n40 34 05 w73 52 58 -- airnav

2) jfk airport
n40 38 39 w 73 46 74 -- facility directory
n40 38 23 w 73 46 44 -- airnav

Notice that only the last group of numbers differ. I do not have an AFD but they must be using format
degrees-minutes-hundredths of minutes while AirNav uses
degrees-minutes-seconds.

The difference is that hundredths of minutes span from 0 to 99 and seconds span 0 to 59.

5 seconds is .09 minutes, 58 seconds is .98 minutes and so on.

Kind of like as 1.5 hours hobbs equals 1 hour and 30 mintues of engine running.