Airlines were gradually resuming services on Saturday, a day after a technology crash disrupted computer systems globally for several hours.

Companies and other organizations have been dealing with a backlog of orders, canceled appointments and delayed travel plans due to the outage.

Tens of millions of people from Brazil to Japan were hit by Friday's massive outage affecting devices running Microsoft Windows, which caused thousands of flights to be canceled, bank services to go offline and several TV channels to fall silent. 

CrowdStrike, the cybersecurity firm, blamed the roll-out of a software update for the outages. CEO George Kurtz told the US news channel CNBC he wanted to "personally apologize to every organization, every group and every person who has been impacted."

What's the latest on air travel?

Operations at Berlin's international airport were largely back to normal on Saturday. A spokesperson told Germany's DPA news agency that flights were on schedule with minor delays, with only two arrivals from the US canceled.

Multiple US airlines and airports across Asia also said they were resuming operations, including in Hong Kong, South Korea, Thailand, India and Singapore.

Spanish airport operator Aena, which earlier reported a computer systems incident, said its IT was up and running again in the afternoon.

Across Latin America, airports were asking passengers to arrive for flights hours earlier than usual. 

Additional flight delays can be expected, particularly on those airlines affected by the outage, as they restore services.

So far, more than 5,000 flights were canceled as a result of the outage, out of more than 110,000 scheduled commercial flights, aviation analytics company Cirium said.

How long will it take until things get back to normal?

"Quite some time," cybersecurity expert Sven Herpig told DW, as firms struggled to update their IT systems,.

CrowdStrike has warned that it could take some time for all of its clients to install the fix and restart their entire computer networks.

As the disruptions were traced back to the flawed software update, Herpig said: "This update should have never passed a quality test, so you can assume that they didn't do the quality test or they didn't do it correctly."

Herpig also said there are no guarantees this won't happen again.

"You can regulate it but in the end of the day, it can happen again and we will likely see it happen again in our lifetime."

How did the cyber outage happen?

Microsoft said the issue began on Thursday and started affecting Windows users running the CrowdStrike Falcon cybersecurity tool. 

Businesses and governments worldwide experienced hourslong disruptions and affected computer after computer started showing the "blue screen of death" error message.

Air travel was immediately hit and from Amsterdam to Zurich, Singapore to Hong Kong, airport operators flagged technical issues that were disrupting their services. While some airports halted all flights, in others airline staff had to check-in passengers manually. Long lines formed at airports across Asia, the US and Europe.

Banks, hospitals and financial services companies warned customers of disruptions and traders across markets spoke of problems executing transactions. Several TV channels were taken off the air, including Britain's Sky News and Australia's ABC.

Companies were left patching up their systems and trying to assess the damage, even as officials tried to tamp down panic by ruling out foul play.

Within hours of the outage, CrowdStrike said the outage was not a security incident or cyberattack. CEO Kurtz said in a statement his teams were "fully mobilized" to help affected customers and "a fix has been deployed."

Experts stress that Friday's disruptions were a reminder that deploying software from only a handful of providers can leave global IT systems vulnerable.

Scores of companies rely on CrowdStrike for their security needs.

mm/sms (AFP, AP, dpa, Reuters)