U.S. Department of Transportation called the cancellation of Southwest Airlines flights “unacceptable

The U.S. Department of Transportation said late Monday night it was conducting inspections of a large number of cancelled and delayed Southwest Airlines flights in recent days to determine whether the carrier could have controlled the cancellations. The department called the huge number of cancelled flights “unacceptable.”

Southwest canceled 2,886 flights (70 percent of the total) on Monday, after canceling 48 percent of its flights on Sunday, according to FlightAware, a flight-tracking website. In addition, the company has already canceled 60% of its flights scheduled for Tuesday.

Southwest has not yet commented on the department’s statement.

“The Department of Transportation is concerned about the disproportionate and unacceptable number of Southwest Airlines flight cancellations and delays and the failure to adequately support customers facing flight cancellations or delays,” the department said in a statement.

The agency promised to scrutinize the circumstances and the companies’ fulfillment of their obligations to customers and regulatory agencies.