REUTERS/Joshua Roberts
Delta passengers in line at Reagan National Airport in Washington D.C.
Even though Delta was able to get some of its planes flying again by 8:40 a.m. Eastern Time, the airline was forced to cancel 1,000 flights on Monday and another 500 flight on Tuesday.
"We were able to bring our systems back on line and resume flights within a few hours yesterday but we are still operating in recovery mode," Delta Air Lines' senior vice president Dave Holtz said in a statement.
Holtz, who is in charge of the nerve center from which the airline is run, also apologized to the Delta passenger who have been left stranded at airports around the world.
So what happened to Delta?
According to the Atlanta-based airline, its computer system lost power Monday morning at 2:30 a.m. Eastern Time. There are backup systems. But for some reason, those backup systems failed to come online.
"Delta likely built a disaster recovery plan into system, but it was properly configured to backup everything that failed," Computer disaster recovery expert Gil Hecht told Business Insider.
"It's possible they didn't make changes to the backup system for it to mirror the main system," Hecht said.
As bad as the situation may seem, it could have been much worse.
"Delta's IT team did phenomenally well," Hecht added. "The fact that they could recover in six hours when disaster recovery didn't work is impressive."
Unfortunately for passengers, what happened to Delta isn't an isolated incident for the airline industry. Less than three weeks ago, Southwest Airlines was forced to cancel thousands of flights due to a failure in its computer system.
JetBlue was forced to ground its planes in January due to a power outage at a data center. In addition, American and United also experienced computer related issues over the past two years that have forced operations to grind to a halt.
What's wrong with airline computers?
The computer infrastructure behind modern airlines are not so modern. Many of which are based on decades-old systems that have been consistently updated over the years.
"There's a lot of patch work upgrades happening in these computer systems," Airways senior business analyst Vinay Bhaskara told Business Insider. "Unfortunately, there isn't anything out there that's a whole lot better than what's already in place."
Bhaskara and Hecht both agree that airlines are spending a ton of money every year on its computer systems and the lack of spending isn't an issue.
For instance, Delta has a large IT staff that has developed many of the features in its computer systems specifically for the airline's needs. Southwest is making major upgrades to its system that's expected to be complete by the early 2017.
Even with airlines investing time and resources in updated computer systems, companies and customers don't seem to be immune to service disruptions.
As a result, this means there has to be a fundamental overhaul of the computer infrastructure across the airline industry for there to be true improvement.
"It takes a lot of inertia for there to be major changes in the industry," Bhaskara said. "That means these computer systems will have to be dragged kicking and screaming into the 21st century."
Bhaskara believes that the change won't come from one of the major airlines or its suppliers. Instead it will likely be a startup airline or tech firm that takes the industry into the future.
We just don't know who will do it or when that will happen.