"Since the announcement of our interim results on February 20 the outbreak has continued to evolve quickly with cases spreading rapidly across the globe," he said.
"We will be monitoring developments over the remainder of the 2020 financial year, including the introduction of any new border restrictions, and we will continue to update guidance if there are further significant changes."
Littlewood said it was a very dynamic situation.
"We are now seeing a significant reduction in flights and in the number of passengers coming through our terminals as governments introduce unprecedented border restrictions and people choose not to travel."
There had been an immediate impact on business travel, and the airport was anticipating a rapid downturn in leisure travel in the coming months, as cancellations flow through and demand for bookings continues to soften.
In January 2020, total passenger numbers were down 3.4 per cent on the January 2019 result. In February 2020, total passenger numbers deteriorated further, falling 8.6 per cent on February 2019.
Initial data for international passengers only for the first 10 days of March has shown an 18 per cent decline on the previous corresponding period in March 2019.
Auckland Airport now anticipates a further downturn in passenger numbers to continue for the remainder of the 2020 financial year.
"This is an extremely challenging time for our industry. As with the airlines, fewer landings and fewer passengers have a direct impact on our aeronautical revenues, so we are all feeling it and sharing in the downturn," said Littlewood.
"The new earnings guidance reflects today's updated view on passenger numbers and our decision to introduce a range of support measures for specific airport partners for the remainder of the 2020 financial year."
Board chair Patrick Strange said the new measures would accompany the work Auckland Airport is already doing with Tourism New Zealand, Auckland Tourism, Events and Economic Development (ATEED) and other government partners to support the tourism market through the outbreak and into the recovery phase when it eventuated.
"For our own business, we are continuing our disciplined approach to operating costs and ensuring our organisation remains resilient as we navigate our way through this challenging period," said Strange.
This week the board of Slot Co-ordination NZ voted to relax airport slot rules so airlines flying in and out of New Zealand have the ability to reduce flight numbers during the impact of Covid-19, with the certainty they can retain their historic slots and re-establish services when market conditions improve. Auckland Airport has been a key supporter of this decision.
Strange said the full impact of Covid-19 on Auckland Airport's operating and financial performance could not yet be determined.
• Tourism Holdings this morning has withdrawn its full-year net profit guidance of $24m because of new travel restrictions announced related to the Covid-19 pandemic.
''While we believe that this remains a possibility, there are too many uncertainties for this to remain as thl's guidance. As a result we do not expect to provide financial guidance for the remainder of the FY20 year.''
