Southwest Airlines is ending its cabin service earlier starting next month. Beginning on Dec. 4, a company spokesperson says flight attendants will begin preparing the cabin for landing at an altitude of 18,000 feet instead of 10,000 feet. The company says it's making the changes to reduce the risk of in-flight turbulence injuries. For passengers, that means they will need to return their seats to an upright position or do other pre-landing procedures earlier than before. While turbulence-related fatalities are quite rare, injuries have piled up over the years.