KOCHI: The Ernakulam District Collector on Thursday banned the flying of drones and other aerial platforms near the Naval Physical and Oceanographic Laboratory (NPOL) in Thrikkakara. The ban was imposed as NPOL came under the defence ministry. There are high-valued research and development activities, including Sonar technology, taking place at NPOL, sources noted. The district administration invoked section 83(1) of the Kerala Police Act to declare the location an high-security area.