New Delhi, April 10 : Amid instances of unruly behaviour by some passengers on flights, aviation regulator DGCA on Monday issued an advisory to airlines saying such incidents have the potential of compromising the safety of aircraft operations. The aviation regulator has advised the heads of operations of all airlines to sensitise their pilots, cabin crew and post holders on handling of unruly passengers through appropriate means. Air India flight AI 111 scheduled to operate from Delhi to London on Monday returned to Delhi shortly after departure due to "serious unruly behaviour" of a passenger on board. An FIR was lodged as the accused person allegedly misbehaved and caused physical harm to two of the cabin crew members. The advisory issued on Monday said that there are provisions under the Civil Aviation Requirement (CAR) for action to be taken by the airline to deal with unruly passengers and the responsibilities of pilots, cabin crew members and the director of inflight services are also mentioned in the CAR. The Directorate General of Civil Aviation (DGCA) has noticed a few incidents such as smoking in aircraft, consumption of alcoholic beverages resulting in unruly behaviour, altercations between passengers and sometimes inappropriate touching or sexual harassment by the passengers onboard an aircraft during the flight, wherein post holders, pilots and cabin crew members have failed to take appropriate actions. Air lines shall categorise all such unruly passenger behaviour into three levels and such people can face a flying ban for varying periods. Unruly behaviour such as physical gestures, verbal harassment and unruly inebriation are classified as Level 1, while physically abusive behaviour like pushing, kicking or sexual harassment will be classified as Level 2. Besides, life threatening behaviour such as damage to aircraft operating systems, physical violence like choking and murderous assault will be considered as Level 3. An internal committee set up by the airline concerned can decide on the duration for which an unruly passenger can be banned from flying. Airlines have witnessed many such incidents of unruly behaviour by some air passengers in the last few months. Last week, in an incident of unruly behavior by an air-passenger, a drunk flyer on board an Indigo flight from Delhi to Bengaluru tried to open the flap of the emergency doors. Subsequently, the matter was reported to the concerned agencies and appropriate action was initiated. /IANS