A computer virus has crippled some Air Canada systems and created delays at check-in counters at Canadian airports, the airline says.
The virus, dubbed "White Hat," hit as the country's largest airline was still reeling from a worldwide shutdown of its operations last Friday, following the massive power blackout in Ontario and the U.S. Northeast.
Air Canada said the virus struck on Tuesday morning and also crippled its call centres.
"It's slowing things up," Air Canada spokeswoman Isabelle Arthur said, adding a fix was being installed by International Business Machines Corp.
The airline expected to resolve the problem before the end of the afternoon.
The virus had not attacked computer systems handling flight operations, Arthur said.
White Hat is what some people are calling a new worm that showed up on Monday, also dubbed "Welchia" or "Nachi," said Patrick Hinojosa, chief technology officer of anti-virus vendor Panda Software.
This new worm follows the worldwide spread of the "Blaster" virus last week, which crashed computers and spread to others and instructed them to launch an attack on one of Microsoft's Web sites.
Although the White Hat worm appeared to be written to clean up the Blaster worm and prevent future infections, anti-virus experts are opposed to the concept of good viruses because they intrude on someone else's computer system without their knowledge and can cause unintended consequences.
The White Hat worm is creating more network traffic, and thus a slowdown, for many corporations as it checks for other vulnerable computers to spread to and because it instructs numerous computers in a network to try to download the patch simultaneously, security experts said.
White hat is the term used for hackers who defend networks against "Black Hat" hackers, who try to attack them.