Air New Zealand is pausing two major routes and making changes to others as it works through engine issues with some planes. 

The national carrier says it's having to adjust its schedule due to the grounding of 16 aircrafts undergoing mandatory engine maintenance by aerospace company Pratt & Whitney. 

It will pause flights to Seoul and Hobart from April and is reducing flights on other routes as well as moving aircraft between routes.  

Chief Executive Greg Foran told Mike Hosking that Pratt & Whitney has to accelerate the process of taking the engines off-wing and checking them.  

He says they're not sure how long it'll last, but it could be two years. 

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