India, Feb. 25 -- The medical evacuation aircraft that crashed in Jharkhand Monday night, killing all seven people on board, had no black box, officials familiar with the matter told HT, in what would likely pose a significant challenge in piecing together the cause of the incident.

Civil aviation rules do not mandate cockpit voice recorders (CVR) or flight data recorders (FDR) for aircraft weighing below 5,700kg. "The accident will have to be studied through communication with air traffic control, analysis of the wreckage, and eyewitness accounts," an industry expert said.

Among the aspects of the flight investigators are probing, according to one of the officials, is whether a faulty onboard weather radar caused the Beechcraft C90 Kin...