KATY, Texas - The sprawling neighborhoods of brick homes, man-made lakes and walking paths in this area west of Houston always have been considered high ground. When the city has flooded, friends and family would flee here to escape, as many did in recent days during Houston’s descent into disaster.But that changed Tuesday, when dozens of rescue helicopters swooped in to airlift the elderly and children from rooftops in neighborhoods with lofty names like Grand Mission Estates and Cinco Ranch.