Delta faces investigation over "continued widespread disruptions"

Driving the news: The U.S. Department of Transportation "has opened an investigation into Delta Air Lines to ensure the airline is following the law and taking care of its passengers during continued widespread disruptions," Transportation Secretary Pete Buttigieg wrote on X Tuesday.

• "All airline passengers have the right to be treated fairly, and I will make sure that right is upheld."
• The department wants to hear from passengers who believe they weren't adequately compensated for travel disruptions, Buttigieg added.

Catch up quick: Problems with widely-used cybersecurity software caused issues across the aviation industry starting Friday.

• Every major U.S. airline except Delta was back to normal operations by Monday morning.

• Delta cancelled 30% of its flights (1,157 total) and delayed 46% (1,796) on Monday, per FlightAware.

By the numbers: Delta's woes have persisted Tuesday, with 12% of its flights (418) canceled and 10% (356) delayed as of about 9am ET.

What they're saying: "Delta is in receipt of the Department's notice of investigation and is fully cooperating," the airline said in a statement Tuesday.

• "We remain entirely focused on restoring our operation after cybersecurity vendor CrowdStrike's faulty Windows update rendered IT systems across the globe inoperable."