Delta Air Lines CEO Ed Bastian

A veteran airline analyst has put the price tag at $120 million for last week's computer outage at Delta Air Lines (DAL - Get Report) and said the outage means the airline will be forced to become "more humble."

Delta's computer outage began Aug. 8, and resulted in about 2,100 cancellations before the carrier resumed normal operations on Thursday.

In a report issued Monday, Cowen & Co. analyst Helane Becker estimated the airline will suffer a $120 million operating income loss from the outage. That includes $50 million in lost revenue combined with a cost of $70 million.

She cited lost revenue from customers who have or will book away from Delta as well as the cost of cancellations, delays and the $200 vouchers that Delta provided to many customers.

Additionally, Becker said, "Delta has historically taken great pride in their operational performance, consistently referring to themselves as running 'the industry's best operation' and citing how many days they went without flight cancellations.

"We expect management to take a more humble approach to addressing their operations going forward," she said.

In fact, in a video he made on Tuesday, Aug. 9, Delta CEO Ed Bastian took a humble approach.

"This isn't who we are," Bastian said. "This isn't the quality of service and the reliability you've come to expect from Delta Air Lines. We're very sorry; I'm personally very sorry for what has happened to you."

Bastian noted that the carrier had already cancelled three times as many flights as it had cancelled all year.

"I'm sorry we let you down," he said. "We'll do everything we can to make certain this does not happen again."

In mid-morning trading on Monday, Delta shares were up 12 cents to $36.47.

Shared closed Friday, Aug. 5, at $37.67. The carrier announced the computer outage before the market opened Aug. 8. Since then, the lowest share price was $35.84 on Friday Aug. 12.

Despite Delta's problems, Becker maintained an outperform rating on Delta stock. Similarly, last week in a note, S&P Global Market Intelligence analyst Jim Corridore kept a strong buy on Delta.

"As long as there are no repeat occurrences of the issue, Delta should not see major customer defections or investors adding an extra risk premium to the shares," Corridore wrote.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.