Southwest Airlines Co. disclosed Monday that it now expects second-quarter revenue per available seat mile (RASM) to decline about 3% from a year ago. That compares with the air carrier's previous guidance range of a decline of 1% to a decline of 3%. The stock was still inactive in premarket trade. Southwest said the new outlook is primarily a result of lower bookings, largely because of reduced marketing efforts following the Flight 1380 accident, in which an in-air engine rupture led to a passenger fatality. Separately, given lighter revenue trends and higher oil prices, Southwest revised its second-quarter growth outlook for available seat miles, or capacity, to 3.5%, from previous guidance of 3.5% to 4.0%. For the second half of the year, the company expects capacity growth of about 6%, down from previous forecast of the low-7% range. The stock has tumbled 22.1% year to date, while the NYSE Arca Airline Index has lost 9.8% and the S&P 500 has gained 2.3%.