Delhi police have written to all Indian air carriers as well as to Delhi airport operator DIAL asking them to display prominent warnings for flyer against carrying bullets. The Hindustan Times has reported that warnings will have to be mentioned prominently on all boarding passes, air tickets and at terminal entry points that carrying ammunition is a non-bailable offence and can land flyers in jail. The letter by the police came in the backdrop of 522 passengers being arrested from Delhi airport in the past five years for carrying live ammunition in their bags, the report said.