The New Zealand Defence Force is helping search for two vessels in Kiribati that failed to return from separate fishing trips last week.
A Royal New Zealand Air Force P-3K2 Orion aircraft left Auckland at 6am and was expected to reach the search area, around 4000 kilometres north of New Zealand, at midday.
One of the missing vessels is a six-metre wooden boat with three people on board.
The second vessel is a four-metre canoe with one person on board.
The Fiji Maritime Surveillance Rescue Coordination Centre, which is responsible for the search area, requested assistance from the NZDF on Sunday, after a search by a local patrol boat failed to find either vessel on Friday.
The two missing vessels were last seen by a local search aircraft late on Friday afternoon.