Heathrow airport warned on Monday that traffic levels hit just 40% of pre-pandemic levels in September, lagging the recovery of its EU rivals.
The airport said in an update that North American traffic is hitting 25% of 2019 levels.
Cargo, which is carried in the hold of passenger planes, was close to 8% down by volume on 2019, reflecting the way in which travel restrictions have been damaging UK exports and supply chains.
The news comes as the UK relaxes its travel traffic light system in order to enable people to move around for the school holidays.
The rule change has made it easier to visit almost 90 countries, with 47 nations now off the red list. As of 4am on Monday morning, those arriving from places including South Africa, Brazil and Argentina no longer need to quarantine in a hotel.
Advice against non-essential travel to 42 other countries was also lifted.
The red list now consists of: Colombia, Dominican Republic, Ecuador, Haiti, Panama, Peru and Venezuela.
With light at the end of the tunnel for Heathrow and despite its poor September traffic, airlines and price comparison websites reported a bump in bookings following the red list announcement last Thursday, with Virgin Atlantic saying bookings to South Africa had doubling overnight compared with the previous week. Jet2 also said bookings had doubled in 24 hours.
Flight search engine Skyscanner also said that redirects from its UK site rose 10% following the red list announcement, compared with the previous day, and TravelSupermarket said bookings had nearly doubled since before the end of the travel traffic light system for international travel in September.
Airline stocks were boosted by the reopening on Monday: International Airlines Group (IAG.L), which owns British Airways, had risen 1.7% by midday in London. EasyJet (EZJ.L) was also up 2% and Ryanair (RYA.L) rose 2.3%. Wizz Air (WIZZ.L) rose 1.1%.
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