I was recently asked if an airport was covered by a Letter to Airmen (LTA) providing IFR separation for VFR practice approaches, and I realized I had no idea. How can I look up LTAs for an airport, and do they ever expire?
They are searchable at FNS NOTAM search: https://notams.aim.faa.gov/notamSearch/
A link is provided to a PDF, containing a link to the actual LTA.
(Filter by LTA, remember the agreement might not be with the airport, but with the ATSU, like the local TRACON/ARTCC, try searching by airport name + radius).
Expiry date is shown in the details view.