NEW DELHI: Investigators have found that an Indian air defence missile was fired shortly before the crash of a Mi17 V5 helicopter at Budgam , near Srinagar on February 27, which resulted in the deaths of six air force personnel and a citizen on ground. The investigators are examining the sequence of events which preceded the crash.The final moments preceding the crash, including if the IFF (Identity, Friend or Foe) systems were switched on or not, are being carefully looked at to determine what went wrong. The air force brass, highly placed sources told ET, has made it clear that it would not shy away from initiating court martial proceedings against personnel if they are found blameworthy in the inquiry.ET has learnt that the focus of the investigation now is to determine if multiple layers of safeguards meant to protect assets from friendly fire failed and how systems need to be improved to prevent any such incident in the future. Sources said that the missile – believed to be of Israeli origin – was activated after an air defence alert was sounded over Jammu and Kashmir , besides other parts of the border, after over 25 Pakistani air force jets were detected along the border on the morning of February 27.The alert, sources said, indicated that Pakistani jets may be trying to breach the border for a strike on Indian military targets and there were concerns that armed UAVs available with that country may also have been deployed. A slow moving target like the Mi 17 V 5 helicopter could potentially be mistaken for a low flying armed UAV homing into an air base, according to these sources.“When an air defence alert is sounded, several things take place. There are a set of rules that transport aircraft and helicopters need to follow and there are set entry and egress routes demarcated for aircraft flying. Also, aircraft are to switch on their IFF (Identify, Friend or Foe) systems,” sources told ET.They added that all angles are being probed to determine if lapses took place and where. A senior officer is conducting the court of inquiry into the crash and has been given access to all inputs available with ground controllers as well as the actions of the helicopter in the ten minutes that it was in the air. As reported by ET, the chopper crashed in the 10-minute span when IAF jets were engaged in an aerial battle with the Pakistan Air Force fighters, along the Line of Control in the Nowshera sector, and air defence systems were on operational alert. Command and control systems were under immense pressure as reports of attempted intrusions were sounded along the border.The Indian side officially acknowledged the crash but has not mentioned it in official statements on the aerial battle and the current conflict with Pakistan. In its official statement, the Pakistani military acknowledged the aerial battle over Nowshera but said its fighters were not involved in the chopper incident.Mi17V5 is one of the sturdiest choppers in service across the world and is not usually prone to technical faults of catastrophic nature. Eyewitness reported that a loud explosion was heard in the air before the chopper crashed in a trail of smoke, indicating a possible catastrophic external event contributed to the incident.