New Delhi: Aircraft accident probe agency AAIB on Tuesday said it is engaged in the systematic collection, preservation and examination of all relevant technical, operational, medical and human factor evidence related to the Air India Phuket-Delhi flight incident last week. On August 4, an Air India Airbus A320 aircraft, registration VT-EXO, operating the flight AI 2379 from Phuket to Delhi, experienced a sudden altitude variation of around 300 feet during cruise. In the incident, injuries were reported to 20 passengers and 4 cabin crew members, the Aircraft Accident Investigation Bureau (AAIB) said in a statement on Tuesday. AAIB said it is presently engaged in the systematic collection, preservation and examination of all relevant technical, operational, medical and human-factor evidence. "This includes examination of the aircraft and its systems, recorded flight data, relevant operational and maintenance records, medical information, and interviews with persons concerned.