Southwest Airlines previously communicated an estimated negative revenue impact in the $10 million to $15 million range for January 1st through 23rd related to the government shutdown. Since then, the airline has announced that it has continued to experience softness in passenger demand and bookings as a result of the government shutdown. As a result, it now estimates the negative revenue impact to first quarter 2019 to be approximately $60 million.Aside from this impact, Southwest says that it has continued to experience strength in year-over-year close-in yields, thus far in first quarter 2019. Based on current bookings and yield trends, it now expects its first quarter 2019 operating revenue per available seat mile (RASM, or unit revenues) to increase in the three to four percent range, year-over-year. This compares with Southwest’s previous first quarter 2019 RASM guidance of a year-over-year increase in the four to five percent range.