Delta's horrible week is getting even worse

For a third day in a row, Delta is expecting flight cancellations resulting from a Monday computer outage at the airline's Atlanta headquarters.

The second largest airline in the world cancelled roughly 1,800 flights over the first two days of the week and has, thus far, cancelled more than 250 flights on Wednesday.

Although the airline expects operations to return to normal by Wednesday afternoon, Delta cautioned that severe weather on the East Coast may cause further delays.

For passengers flying on Delta, the airline has extended its waiver program - which will allow customers to rebook flights free-of-charge - to August 21.

In addition, Delta is offering $200 traveler vouchers for those who were delayed for longer than three hours or had their flights cancelled.

The airline's 800-aircraft fleet was effectively crippled for more than six hours on Monday due to the outage.

"Monday morning a critical power control module at our Technology Command Center malfunctioned, causing a surge to the transformer and a loss of power, Delta COO Gil West said in a statement on Tuesday. "The universal power was stabilized and power was restored quickly."

However, the trouble didn't end there. A Delta spokesperson confirmed to Business Insider Tuesday morning that the airline's backup systems failed to kick in.

West went into detail on why the airlines backup systems didn't function properly.

"Critical systems and network equipment didn't switch over to backups. Other systems did," West said. "And now we're seeing instability in these systems."

As a result, the airline is seeing, "slowness in the system that airport customer service agents use to process check-ins, conduct boarding and dispatch aircraft," West added.

In addition, the cancelled and delayed flights have also wreaked havoc on the airline's crew and fleet schedules. Thus, further delays and cancellations have been caused by scheduling difficulties.