From 828,230 in 2019, only 185,707 passengers were recorded in 2020.
Although lockdowns may have ended, the ongoing pandemic is still having an impact, said the airport’s annual report.
‘The effect of varying legal restrictions on non-essential travel, self-isolation and lockdown measures in the Bailiwick of Guernsey and other jurisdictions continues to have a significant impact on airlines, airport operators, and third-party contractors working in the civil aviation sector in the British Isles, Europe and the rest of the world,’ it said.
The operating costs per passenger movement also rose as a result of the fall in numbers.
While in 2019 it had cost the airport £15.36 per passenger, last year that figure was £22.61.
Similarly, the cost per passenger of navigational services was a lot higher than in 2019, rising from £4.90 to £22.27.
Movements were also hit by Flybe entering liquidation shortly before the pandemic hit. The report said it had been responsible for about 12% of the annual passenger traffic at the airport.
Some services did run while others did not, however, including the Alderney route and the air bridge with the Isle of Man which started in July.
‘Both services generated an opportunity for islanders to travel overseas and there was a high degree of popularity across both destinations,’ said the report.
The London Gatwick and Southampton routes saw the most activity during the year. A total of 52,155 people used Gatwick, which was down about 83% over 2019’s total of 310,040. From a peak of 20,783 in February, the numbers fell to 60 in April and 41 during the whole of November.
The Southampton route, meanwhile, saw 45,198 passengers in 2020 compared to 148,202 the year before, a drop of just under 70%.
Of the major routes, Southampton was the only one which saw movements every month.
The air bridge with the Isle of Man ran from July to October inclusive and was used by 8,161 passengers.