Queenstown Airport has started work on sealing its grass crosswind runway, which is closed up to 50 times a year due to unsafe surface conditions.
Work on the runway, which services aircraft weighing up to eight tonnes, is more than half complete, having started 11 days ago.
Queenstown Airport Corporation chief executive Steve Sanderson said: "The advantages are clear in that it's easier maintained and we can keep the runway going these 50 days a year when snow and other issues would keep it from opening."
In a QAC notice of requirement to Lakes Environmental, ongoing maintenance and irrigation of the runway was said to be "costly", and noted concerns about safety in certain conditions.
The work of laying asphaltic concrete on a base layer was originally expected to take between six and eight weeks.
During the works, the aircraft normally using the crosswind runway are sharing use of the main runway, and will return to the new surface once complete.
