The job of a Flight Attendant is traditionally a very high turnover position, and this is no different at Air New Zealand. Your interviewer is fully aware of the high amount of investment that Air New Zealand puts into the training and development of their staff. To try and gauge your long term commitment to the airline, your interviewer is posing this question. A hiring manager will not want to hire you if they think you will not stay in the position for very long. Assure the interviewer that hiring and training you would be worth the investment of time.