Dozens of airlines from Asia to the United States said they had carried out a snap software retrofit ordered by Airbus, and mandated by global regulators, after a vulnerability to solar flares emerged in a recent mid-air incident on a JetBlue A320.
Airbus said on Monday that the vast majority of around 6000 of its A320-family fleet affected by the safety alert had been modified, with fewer than 100 jets still requiring work.
But some require a longer process and Colombia's Avianca continued to halt bookings for dates until December 8.
Sources said the unprecedented decision to recall about half the A320-family fleet was taken shortly after the possible but unproven link to a drop in altitude on the JetBlue jet emerged late last week.
Shares in Airbus were down two per cent in early trading in Paris.
Following talks with regulators, Airbus issued its alert to hundreds of operators on Friday, in effect ordering a temporary grounding by ordering the repair before next flight.
"The thing hit us about 9pm (Jeddah time) and I was back in here about 9.30. I was actually quite surprised how quickly we got through it: there are always complexities," said Steven Greenway, CEO of Saudi budget carrier Flyadeal.
The instruction was seen as the broadest emergency recall in the company's history and raised immediate concerns of travel disruption, particularly during the busy US Thanksgiving weekend.
The sweeping warning exposed Airbus not having full real-time awareness of which software version is used given reporting lags, industry sources said.
At first airlines struggled to gauge the impact since the blanket alert lacked affected jets' serial numbers.
Over 24 hours, engineers zeroed in on individual jets.
Several airlines revised down estimates of the number of jets affected and time needed for the work, which Airbus initially pegged at three hours per plane.
"It has come down a lot," an industry source said on Sunday, referring to the overall number of aircraft affected.
The fix involved reverting to an earlier version of software that handles the nose angle.
It involves uploading the previous version via a cable from a device called a data loader, which is carried into the cockpit to prevent cyberattacks.
UK's easyJet and Wizz Air said on Monday they had completed the updates at the weekend without cancelling any flights.
Australian budget carrier Jetstar fully resumed flights on Sunday after engineers fixed the airline's planes that had the anomaly.
JetBlue said late Sunday it expected to have completed work to return to service 137 of 150 affected aircraft by Monday and plans to cancel about 20 flights for Monday due to the issue.
Questions remain over a subset of generally older A320-family jets that will need a new computer rather than a mere software reset.
The number of those involved had been reduced below initial estimates of 1000, industry sources said.
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