It is most likely due to a a weather station being installed at the
airport. I believe ICAO does not allow numbers in airport codes.


Matt Whiting wrote:
Is anyone aware of a source for changes in airport identifiers? I flew
into Hilton Head twice years ago and the first time I listed the ID as
49J and the second time as HXD. The first flight was in 1994 and the
second in 1996. I did a decode on 49J and it shows as a non-existent
identifier. HXD is current for Hilton Head. I found a few sites that
say the ID changed with airline service was added, but I've not found
any site that contains such history in general.

Matt