Lacore apologized to employees for the extra steps the emergency call in procedure require for those who are ill but said it is required to 'keep the operation running.'' 'We simply cannot manage the operation with the number of sick calls we are taking and quickly using reserves,'' Sonya Lacore, Southwest's vice president of inflight operations, said in a memo to flight attendants viewed by USA TODAY. On Friday, Southwest implemented its emergency sick call procedures for the second time in a week due to a spike in flight attendants calling in sick, a level the airline deems 'excessive.'' 'Excessive'' flight attendant sick calls a factor? 'To proactively manage our operation, we implemented a scheduled reduction ahead of expected storms and probable air traffic control initiatives,'' he said in a statement. On Friday, Southwest spokesman Dan Landson attributed Friday's cancellations to summer storms. 'These proactive cancellations will allow us to minimize delays and diversions due to the storms and probable ATC (air traffic control) initiatives,'' she said in a statement. Southwest spokeswoman Alyssa Foster told USA TODAY on Saturday that the airline proactively canceled 150 flights 'due to widespread thunderstorms expect across parts of the nation.'' She cited cities including Denver, Orlando, Chicago and St. The cancellations and delays come a week after Southwest canceled or delayed hundreds of flights due to two separate technology issues and a week after American Airlines struggled with operational woes during the busy Father's Day travel weekend and said it would proactively cancel nearly 1,000 July flights to give it more breathing room when weather and other issues crop up. Tardy flights are a big issue, too: Southwest delayed nearly 1,600 Friday flights, or 43% of its flights, more than any U.S. airline, and so far Saturday has delayed 960 flights, or 28% of its flights, according to FlightAware. carrier, in total and as a percentage of flights, each day.įlight challenges: Did you get denied a refund when your flight was canceled? See which airlines got the most complaints. It had the most cancellations of any U.S. ET, after canceling 254 Friday flights, or 6% percent of its flights, according to flight tracker FlightAware. Southwest canceled 287 Saturday flights, or 8% of its flights, as of 5:30 p.m. The operational woes come amid a spike in flight attendant sick calls, but the airline says bad weather across the country is to blame. Southwest Airlines has canceled more than 500 weekend flights and delayed more than 2,500 others, the continuation of a rough month for the nation's largest domestic carrier and its passengers. Watch Video: Summer air travel: What to know about cancellations, reimbursements

Southwest cancellation policy