THIRUVANANTHAPURAM: The height restriction rule set by the Airports Authority of India (AAI) for buildings in the vicinity of Thiruvananthapuram airport is posing hurdles for builders and those who want to buy flats. Many flat owners in Akkulam and Kazhakootam are struggling to sell their properties as they have been caught in a legal wrangle between the corporation and the builders over violation of AAI rules regarding the permissible height for buildings near the airport. Since AAI rules are uniform to all airports in the country, Thiruvananthapuram airport is the worst hit as it is located in the heart of the city.