Coimbatore.This black box will help ascertain the crew members’ conversation with each other before the Mi 17 V5 chopper crashed, especially in the light of reports that the crash occurred over poor visibility. .A three-tier security is in place at the Wellington hospital, where the lone survivor Captain Varun Singh is undergoing treatment. .More than 600 cops roped in from Coimbatore, Nilgiris, and Tirupur districts have been deployed in the Coonoor area and vehicle checks were intensified. .A DNA test will be done to ascertain the identity of the deceased persons..Are you in Chennai? Then click here to get our newspaper at your doorstep!!