“This type of disruption is not acceptable to the Delta family who prides itself on reliability and customer service,” Bastian wrote. Eventually, the airline began to issue waivers for passengers to board later flights.

This is not the first time Delta has suffered widespread technical difficulties. In August, a power outage in its operation center caused more than 2,000 flights to be canceled over three days.

The airports most affected by Monday’s computer breakdown were Atlanta, Detroit, Minneapolis and La Guardia, according Flightaware.com.

To make matters worse, the outage coincided with confusion and protests in reaction to Donald Trump’s recent, surprise Executive Order, which has banned individuals from seven Muslim countries from entering the United States.

In a series of Twitter posts on Monday morning, Trump blamed the turmoil on Delta’s technical delay, while at the same time tossing insults at the tears of Senator Chuck Schumer (D., NY). Representatives from Delta have declined to comment on Trump’s Tweets.

Delta is the country’s second-performing commercial airline in terms of traffic, and it has a record of relative reliability and timeliness, at least compared to several of its major competitors. But still, an inspection after the August meltdown revealed that 300 of the airline’s 7,000 servers were not wired to backup power.