My 6th and final Azores beacon confirmed (there are only 6 active NDBs on the Azores) is PI on 420 kHz. This beacon is located on Pico Island. Pico Airport is also a smaller airport operated by Sata Aeródromos. But in addition to flights to the island of Terceira and Sao Miguel it also offers flights to Lisbon in mainland Portugal.

My report was confirmed by Marco Figueiredo from Nav Portugal.