Air New Zealand has again suffered due to an outage at IBM's data center in New Zealand, but this time it was not alone.

A power failure at IBM's Newton Data Center in Auckland also affected the Bank of New Zealand's online banking services.

IBM only recently announced it had signed a contract to continue services for Air New Zealand, following an embarrassing outage in September which left 10,000 Air New Zealand passengers stranded and delayed when routine data center maintenance went wrong.

At the time, Air New Zealand CEO Rob Fyfe said:  "In my 30-year working career, I am struggling to recall a time where I have seen a supplier so slow to react to a catastrophic system failure such as this and so unwilling to accept responsibility and apologise to its client and its client's customers.

This time the airline's booking and check-in system went down, leaving the airline to rely on manual services, according to a report by New Zealand's Stuff.co. 

The failure occurred at 9:30pm Wednesday New Zealand time and affected the airline for an hour, and te bank for four hours.

IBM said the power shortage again happened during routine data center maintenance and its UPS took "several seconds to activate" and longer to bring servers back online.