Sonam Kapoor-starrer "Neerja", a biographical thriller based on a real-life incident of Mumbai-based air hostess caught in a hijack drama, celebrates its first anniversary on Sunday. On this occasion, producer Atul Kasbekar thanked all those who made the film happen."Can't believe it's a year since our debut production ‘Neerja' released. Thank you to all the amazing people who believed and made it happen. Grateful," Kasbekar tweeted on Sunday.Directed by Ram Madhvani, the film revolves around the hijacking of Pan Am flight 73 in Karachi. It throws the spotlight on the flight's head hostess, Neerja Bhanot, who was killed while helping to save over 300 passengers aboard the aircraft.Sonam essayed 22-year-old Neerja, and won over audiences and critics alike with her performance.Shabana Azmi, Shekhar Ravjiani and Yogendra Tiku played pivotal roles. Shekhar considers "Neerja" as a milestone in his life. "Some milestones in our lives will always be extra special...they help us discover a side of ourselves that we never realise existed," he tweeted on Sunday.The film was a box office success and swept all major awards, including six Filmfare.