Forty critical obstacles out of 365 on the approach and departure path for planes at the Indira Gandhi International (IGI) Airport here, which could have posed a hazard to flight operations, had been removed, sources in the airport said today. They added that a fresh "check survey" would be carried out by the GMR-led Delhi International Airport Limited (DIAL) later this year to validate the findings of another survey conducted two years ago, which had identified 365 structures obstructing the flight path. Most of these structures were in the form of permanent buildings and the only way to address the issue was through mitigation, the sources said. For example, it could be done by fixing a light atop a building or modifying the building structure, they added. "Our obligation is to identify the obstacles and ask the competent authorities such as the Airport Authority of India (AAI) to notify them," a source said. As a first step, DIAL is serving notices to various erring parties, while both DGCA and DIAL are working to remove the obstacles that are beyond the airport premises. The findings of the last survey were presented before the Delhi High Court in March. The court, hearing a PIL on the matter, had directed the airport and the local authorities to submit a list of the obstacles, along with their details, and a report on the action taken to remove those. "We are governed by the International Civil Aviation Organisation (ICAO) and deviations from guidelines are taken seriously. It is the same here," a source said. DIAL is also reaching out to individual households and keeping a track of the construction in the surrounding areas of the airport. According to the guidelines, there should be no high-rise buildings within the approach funnel of any airport in order to provide a safe glide path to aircraft. But unauthorised constructions have become a major issue around airports not only in Delhi, but in other cities as well. No-objection certificates (NOCs) were obtained through manipulation in the absence of clarity as regards the height of the buildings falling on the flight path, an AAI official said.