Stephen McNaught wrote:

If (s)he's refering to K1B9, Mansfield, Mass., then it does not have an
ILS. Don't know when the beeping was heard, but there are other airports in
the area that do have ILS approaches.

There is no such identifier as K1B9. The Mansfield, Mass airport is 1B9. ICAO
identifiers do not have numbers in them.