I wonder: at what altitude above ground does the GPWS issue a warning? Looking at the approach plate, there seems to be nothing above 4,000 to 5,000ft along that arc. So, if the aircraft was at 7,800ft, why the alert?
Also, the pie chart shows 10,700ft if approaching from the East, which this flight presumably was.
Puzzling!
By the way, the approach plate shows the arc with a note "NoPT". What does that mean?