“The U.S. Department of Transportation’s Office of Aviation Consumer Protection is investigating Delta Air Lines following continued widespread flight disruptions and reports of concerning customer service failures,” the DOT said in a Tuesday statement. 

“This process will continue to evolve as DOT learns more and processes the high volume of consumer complaints we have already received against Delta.” 

Delta canceled or delayed more than 2,900 flights on Monday, according to the flight-tracking website FlightAware.  

Multiple airlines faced technology issues starting late last week when a global internet outage hit businesses worldwide.

While many airlines were disrupted by the outage, caused by a CrowdStrike update gone wrong, Delta was by itself in still having substantial cancellations through Monday. It canceled more than 1,300 flights Sunday and around 1,200 flights on both Friday and Saturday. 

“Like many companies worldwide, Delta was impacted on Friday morning by an outside vendor technology issue, which prompted us to pause flying while our systems were offline,” Delta CEO Ed Bastian said in a Sunday statement to customers. 

“The pause in our operation resulted in more than 3,500 Delta and Delta Connection flights cancelled through Saturday,” Bastian continued. “Cancellations continue on Sunday as Delta’s teams work to recover our systems and restore our operation. Canceling a flight is always a last resort, and something we don’t take lightly.” 

Transportation Secretary Pete Buttigieg said in a Sunday post on X that he “made clear to Delta that we will hold them to all applicable passenger protections.” 

The Hill’s Tara Suter has more here.