Apparently, the Federal Aviation Administration (FAA) expects the owners of two private airports in the Midwest to be inconvenienced and accept liability so that a third private airport can be redesignated “public” by requiring that they sign an agreement to accept a non-standard traffic pattern and use the common traffic advisory frequency 122.9 Mhz, which they already use without signing an agreement. To sign any agreement would essentially make the owners liable if they or others using their airports violated it.
Many public airports use non-standard traffic patterns for their runways, oftentimes to avoid residential areas. So, if there is a traffic pattern conflict with other nearby private airports, one would think that the airport wishing to become a public airport would accept a non-standard traffic pattern and not inconvenience the other two airports and make them liable if they violated the procedure.
Other considerations are local zoning restrictions and liability insurance.
One option a private airport could consider if its owner wanted to be open to the public is to change its designation from “private” to “private, open to the public.”
For additional information, contact your state aeronautics office, the FAA and AOPA.