Thousands of Kiwis could be caught by a computer glitch that has grounded British Airways flights through London, a Kiwi travel agent says.
House of Travel commercial director Brent Thomas said the airline's global computer system failure came at the peak time for New Zealanders travelling to Britain.
British Airways chief executive Alex Cruz said the failure, caused by a power supply problem, had forced the cancellation of all flights from London's Heathrow and Gatwick airports, disrupted BA's flight operations worldwide and also hit its call centres and website.
"We are extremely sorry for the huge inconvenience this is causing our customers and we understand how frustrating this must be, especially for families hoping to get away on holiday," he said.
Thomas said such a wide-scale computer malfunction was "a biggie".
"For a major airline to be out with an IT issue being down for a period of time, that is unusual," he said.
"Typically from the start of May to the end of September is the peak time [for travel to Britain]. We will likely have thousands of people in the UK right now, or heading to the UK, of which a reasonable percentage will be on British Airways because it's a big airline and has a good reputation."
He said insurance cover for the resulting disruption would be on a case-by-case basis.
"Just because you have a disrupt doesn't mean you automatically have an insurance claim," he said.
"For example, if someone has a flight that was due to leave at 9.30pm and doesn't go out till say 1am, but doesn't impact on any other part of it, then there is not an insurance claim.
"However if someone is missing a connection, we need to sit down with the insurance company and tell people what that will mean."
He said the airline's IT teams were working "tirelessly" to fix the problem and there was no evidence of any cyber attack.
The problems, which passengers said had affected flights across Britain, came on a particularly busy weekend with a public holiday tomorrow and many children starting their school half-term breaks.
Terminals at Heathrow and Gatwick became jammed with angry passengers, with confused BA staff unable to help as they had no access to their computers.
BA said it would try to get affected customers onto the next available flight although the rebooking process was being hindered by the system problems. Those unable to fly would get a full refund, Cruz said.
"We hope to be able to operate some long-haul inbound flights tonight, which will land in London tomorrow," he said.
Some passengers said they had boarded flights but were then left stuck on the runway.
Airlines depend on huge, overlapping and complex IT systems to do just about everything, from operating flights to handling ticketing, boarding, websites and mobile phone apps. Some critics say complex airline technology systems have not always kept up with the times.
And after years of rapid consolidation in the business, these computer systems may be a hodgepodge of parts of varying ages and from different merger partners, all layered on top of each other.
A union official, meanwhile, blamed BA cost cutting for the travel chaos, saying the airline had laid off hundreds of IT staff last year and outsourced the work to India.
"This could have all been avoided," said Mick Rix, national officer for aviation at the GMB union.
While not that frequent, when airline outages do happen, the effects are widespread, high-profile and can hit travelers across the globe.
BA passengers were hit with severe delays in July and September 2016 because of problems with the airline's online check-in systems.
In August 2016, Delta planes around the world were grounded when an electrical component failed and led to a shutdown of the transformer that provides power to the airline's data centre. While the system moved to backup power, not all of the servers were connected to that source, which caused the cascading problem.
Delta said it lost US$100 million in revenue as a result of the outage. In January it suffered another glitch that grounded flights in the US. That same month, United also grounded flights because of a computer problem.
In July, meanwhile, Southwest Airlines canceled more than 2000 flights after an outage that it blamed on a failed network router.
After the recent outages, outside experts have questioned whether airlines have enough redundancy in their huge, complex IT systems and test them frequently enough.