Both Fiji Airways and Samoa Airways hired versions of the Boeing 737 MAX, which were grounded in March after two fatal crashes.
The plane's manufacturer, Boeing, this month acknowledged a new software issue with the MAX, but would not say how or if it would affect the plane.
Samoa Airways said it was monitoring developments with the MAX, and that it was finalising options to replace the 737-800 it had leased.
Fiji Airways said it had been in regular contact with Boeing and that it had confidence in the manufacturer to fix the problems.