Air New Zealand Limited – Annual report – 30 June 2019
9. Property, Plant and Equipment (extract)
Estimates and judgements are applied by management to determine the expected useful life of aircraft related assets. The useful lives are determined based on the expected service potential of the asset and lease term. The residual value, at the expected date of disposal, is estimated by reference to external projected values and are influenced by external changes to economic conditions, demand, competition and new technology. Residual values are denominated in United States dollars and are therefore sensitive to exchange fluctuations as well as movements in projected values. Residual values and useful lives are reviewed each year to ensure they remain appropriate. During the year ended 30 June 2019 the residual values of the aircraft were reassessed and depreciation expense was reduced by $4 million (30 June 2018: decreased by $6 million).