Air travel was set to face massive disruption on Saturday as airlines worldwide began grounding or delaying flights in response to a software issue. A fix has now been deployed, with the implementation time ranging from 'a few hours' to 'weeks'.

Fears of days of travel chaos across Europe and the world eased on Saturday after plane manufacturer Airbus intervened rapidly to implement a software upgrade it had said was immediately needed on some 6,000 of its stalwart A320 planes.

The announcement by Europe's top plane manufacturer late Friday that the planes could not fly again until the switch was made followed an incident in the United States and raised concerns that hundreds of planes would need to be grounded for long periods.

But several leading European airlines said there had been minimal or no cancellations as a result, although there were indications the situation was more problematic in Latin America and Asia.

Airbus instructed its clients Friday to take "immediate precautionary action" after evaluating a technical malfunction on board a JetBlue flight in October.

"Intense solar radiation may corrupt data critical to the functioning of flight controls," it said, adding that "a significant number of A320 Family aircraft currently in-service" may be affected.

Replacing the software will take "a few hours" on most planes but for some 1,000 aircraft, the process "will take weeks", a source close to the issue told AFP.

- 'Far fewer' than feared' -

French Transport Minister Philippe Tabarot told BFMTV that the aircraft manufacturer had been able to correct the defect "on more than 5,000 aircraft" on Friday and during the night from Friday to Saturday.

He indicated that the number of aircraft requiring more prolonged servicing could be much lower than the 1,000 originally feared.

"According to the latest information I have... it would seem that there would be far fewer A320s that would be impacted in a more prolonged way by the software change."

"We had evoked the possibility of a thousand aircraft. It seems that we are now only talking about a hundred," he added.

Produced since 1988, the A320 is the world's best-selling aeroplane. Airbus sold 12,257 of the aircraft by the end of September compared with the sale of 12,254 Boeing 737s.

Air France told AFP it would be able to "transport all of its customers" on Saturday with the exception of flights on its Caribbean regional network. Air France had cancelled 35 flights on Friday.

German airline Lufthansa added for its stable of carriers that "most of the software updates were completed overnight and on Saturday morning", with no flight cancellations expected but isolated delays not excluded.

Budget airline giant EasyJet indicated that it had not cancelled any flights, as the work on all its A320s was complete.

French Economy Minister Roland Lescure also stated on BFMTV that "for the vast majority of these aircraft", the software update "can be done remotely, it is quite fast".

- 'Safety paramount' -

On October 30, a JetBlue-operated A320 aircraft encountered an in-flight control issue due to a computer malfunction.

The plane suddenly nosedived as it travelled between Cancun in Mexico and Newark in the United States, and pilots had to land in Tampa, Florida.

US media quoted local firefighters saying that some passengers were injured.

Contacted by AFP, JetBlue did not comment on the incident but said it had already begun necessary changes on some A320 and A321 models.

Its competitor, American Airlines, said it had already begun updating software following Friday's alert, and expected "the vast majority" of approximately 340 affected aircraft to be serviced by Saturday. "Several delays" would occur as a result, it added.

After initially saying it had not been affected, its competitor United Airlines said it had identified six affected aircraft and said it expected minor disruptions on a few flights.

Air India warned Saturday of delays and Colombian airline Avianca said 70 percent of its fleet had been impacted and warned of "significant disruptions in the next ten days", suspending ticket sales until December 8.

In the Philippines, local carriers Philippine Airlines and Cebu Pacific were offering refunds or rebooked tickets after grounding at least 40 domestic flights on Saturday.

"These measures may cause short-term disruption to flight schedules and therefore inconvenience to passengers," the European Union Aviation Safety Agency (EASA) said in a statement, adding that "safety is paramount".