Auckland International Airport said Covid-19 travel restrictions were responsible for an 80.9 per cent decline in its net profit to $28.1 million for the six months to December 31.
The company, in its earnings outlook for the full year to June 30, said it expects to report a net loss of between $35m and $55m.
Revenue for the six months fell by 64.9 per cent to $131.5m and its operating profit dropped by 68.4 per cent to $88.2m.
The company's earnings per share fell by 84.1 per cent to 1.91 cents.
Auckland Airport said its net underlying loss for the half came to $10.5m.
The closure of the New Zealand border from March 20, 2020, to all but New Zealand citizens and permanent residents has had a significant impact on international services, the company said.
Chief executive Adrian Littlewood said the timing of the recovery would remain uncertain in the coming five months of the 2021 financial year.
"While we have already seen a partial recovery of domestic travel and the opening of one-way quarantine free travel to Australia, our recovery path is strongly linked to two-way quarantine free trans-Tasman travel," said in a statement.
Auckland Airport is reducing its capital expenditure guidance for the 2021 financial year to between $200m and $230m the company continues to take a measured approach to capital expenditure, Littlewood said.
Chair Patrick Strange said the first half of the 2021 financial year had continued to be a challenging time for both the company and the wider aviation industry.
"While we were pleased to see domestic travel starting to rebuild, international travel has remained at very low levels," he said.
Over the six months, the total number of passengers decreased to 2.8m, down 73.4 per cent on the previous six-month period a year earlier.
Domestic passengers fell 44.6 per cent to 2.6m, and international passengers decreased 96.8 per cent to 187,003.
Core operating expenses were reduced by $33m, or 34 per cent, in the six months
The company also scaled back its significant infrastructure expansion programme while continuing to focus on upgrading critical infrastructure assets such as runways and roads.
Nevertheless, the lower number of passengers, especially international and transit passengers, resulted in significant decreases to the airport's key aeronautical, retail and transport income.
Revenue from its hotel operations and its investment in Queenstown Airport also declined.
The partial recovery of New Zealand's domestic travel market was a positive sign in the first half of the 2021 financial year.
The ongoing success of Auckland Airport's commercial property business was a highlight of the first half of the 2021 financial year.
Property revenue increased 2.4 per cent to $47m driven by rental growth in the existing property portfolio and a part-year contribution from the large new Foodstuffs distribution centre.
The airport has a number of new commercial developments currently under construction which it expects to be valued at more than $223m on completion, with an annualised rent roll of $116m.
The company's commercial property portfolio is now valued at about $2.4 billion.
On the maintenance side, the company successfully completed the replacement of more than 360 concrete slabs in the runway's east and west touchdown zones and made progress on an upgrade of the airside fuel network.
Last month, the airport began a pavement upgrade across the airfield's taxiways and apron and restarted work on a new one-way exit road system for the international terminal in line with future terminal development plans.
Shares in the airport last traded at $6.97, having dropped by 17 per cent over the last 12 months.bh