The COO of Southwest Airlines will testify next week before a senate committee looking into massive flight delays around the Christmas holiday. Andrew Watterson will appear next Thursday before the Senate Commerce Transportation and Space Committee. The hearing—titled “ “Strengthening Airline Operations and Consumer Protections,” —will delve into the causes of massive delays and cancellations that impacted thousands of Christmas travelers. The problems were most pronounced at Southwest, which cancelled some 17,000 flights , leaving passengers stranded—sometimes for days—at airports around the country.