It could take “weeks” to fix a global IT outage which grounded more than 5,000 flights, an expert has warned, as the full impact of the software bug becomes clear.

The outage spread globally on Friday morning after an update from global cybersecurity firm CrowdStrike knocked many Microsoft Windows PCs offline with a “blue screen of death” appearing on screens.

The issue caused travel cancellations and left NHS systems inaccessible.

The company’s founder later confirmed it was caused by a bug in the update and not a cyber attack, as some had feared.

Follow live: Major services affected by global outage

George Kurtz said while a fix had been rolled out, it would be “some time” before all systems are returned to normal and an industry expert warned it could take “weeks” for a full recovery.

Adam Leon Smith of BCS, the Chartered Institute for IT, said: “The fix will have to be applied to many computers around the world.

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“So if computers are getting blue screens and endless loops, it could be more difficult and take days and weeks.”

As the outage became apparent early on Friday, airlines around the globe warned delays were ahead – and cancellations soon hit too, on what should have been the busiest day of the year so far for UK air travel.

Queues snaked around terminal buildings and passengers reported waits of three hours at some UK airports, as systems including check in, eGates and departure boards failed.

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What we know so far
Services affected by the outage

By 8pm, 5,078 flights had been grounded worldwide – which equates to 4.6% of all scheduled flights globally, according to an aviation analytics company.

Cirium Data added that 167 flights that should have left UK airports have been cancelled so far – which is 5.4% of departures – while 171 inbound arrivals were cancelled.

Meanwhile, staff were left handwriting boarding passes and using whiteboards to display departure information as they attempted to keep passengers moving.

The NHS was hit by the outage as “the majority of GP practices” in England and two thirds of those in Northern Ireland were impacted, while South Western Railway said its ticket vending machines had failed.

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Customers also reported issues with supermarket payments, online banking and communications systems including Microsoft Teams.

What has CrowdStrike said?

Speaking on NBC’s Today Show on Friday, CrowdStrike chief Mr Kurtz said: “We’re deeply sorry for the impact that we’ve caused to customers, to travellers, to anyone affected by this.”

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“Many of our customers are rebooting the system and it’s coming up and operational because we fixed it on our end,” he continued.

“Some of the systems that aren’t recovering, we’re working with them, so it could be some time for some systems that just automatically won’t recover, but it is our mission to make sure that every customer is fully recovered.”

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