The article doesn't explain the cause but it sounds exactly like something that could be turbulence: > In the incident on Monday, passengers arriving in Auklan

The article doesn't explain the cause but it sounds exactly like something that could be turbulence: > In the incident on Monday, passengers arriving in Aukland told local media that the plane quickly lost altitude, flinging those unsecured towards the ceiling. > A passenger told radio network RNZ that “people flew through the air because they weren’t wearing their seatbelts”. Like I said that doesn't mean it was turbulence - but the basic concept of keeping your belt on when seated would have likely prevented most injuries.