Back in coach, Anna Wallace McCrummen, 45, organizes the cart of drinks and food for sale that would later be pushed down the narrow aisle, and then takes a blue rubber mallet to whack a bag of ice cubes that had frozen into a solid block. She hits it over and over again, perhaps a little too keenly, as the sound — thwop, thwop, thwop — echoes off the walls of the small galley.