New Delhi, Aug. 11 -- Airbus on Monday said it was sending specialists to assist an investigation into the sudden altitude loss of an Air India A320neo aircraft last week, even as people familiar with the matter cited a preliminary defect report (PDR) prepared by the pilots to suggest that the incident was preceded by multiple technical glitches, including an autopilot disconnection. With the Aircraft Accident Investigation Bureau (AAIB) commencing its probe into the August 4 incident, teams from the French agency, Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA), as well as the aircraft's manufacturer Airbus will assist in the probe, as per the standard operating procedures. The Phuket-Delhi flight AI2379 experienced a sudden loss of altitude of around 300 feet during cruise, causing injuries to 13 passengers and four crew members. An initial statement from Air India had cited turbulence as the reason. Soon after the incident, the aircraft, with 137 passengers and eight crew members on board, stabilised and landed safely in Delhi. The pilots of the flight have been off-rostered pending probe. The pilot-in-command's (PIC) preliminary drug test returned "non-negative", a government release said. The results of a confirmatory second test is awaited. Two persons aware of the matter said the pilots had mentioned technical issues with the aircraft in the PDR. "The PDR mentioned that the autopilot disconnected. It also mentioned a stall warning and a flight control ECAM (Electronic Centralised Aircraft Monitor) message," said one of these persons, requesting anonymity. Sam Thomas, president of Airline Pilots' Association of India (ALPA India), said the first officer took control of the situation, citing papers filed by the airline with the aviation regulator. "The pilots followed the rule book while cruising. The aircraft's technical glitches were handled well and within time by the first officer."...