Indonesia and Malaysia are continuing a joint search and rescue mission for the missing Air Asia flight QZ8501. The plane vanished on Sunday over the Java Sea en route between Indonesia and Singapore.
The missing plane is an Airbus A320-200. There are more than 3,500 of the A320 range of aircraft – which include the A319 and A321 – currently in use. These planes have an excellent safety record, according to manufacturer Airbus. Since the A320 planes were introduced in 1988, they have been involved in 10 accidents that have ended in fatalities, of which three were later blamed on pilot error.
According to a safety study by Airbus' competitor Boeing, just 1-in-10 fatal accidents involving aircraft occur when planes are at their cruising altitude: the remaining 90% of accidents occur during take-off and landing. As flight 8501 was scheduled to take two hours, and contact was lost 42 minutes after take-off, it suggests the plane had reached cruising altitude.
Another potential cause of a crash is metal fatigue, caused by the stress of take-off and landing, and pressurisation and depressurisation from moving between different altitudes, causing wear and tear on a plane's metal frame. However, this cause is unlikely, as this A320 had only been flying for six years, and is reported to have had safety inspection in November 2014.
Bad weather is a likely cause. This has been a factor in past disasters, which include the crash of the Air France Flight 447 into the Atlantic Ocean in 2009, which began when the plane was at cruising altitude.
The final communication between flight 8501's pilot and air traffic control came in on Sunday at 6:13am (Saturday, 11.13pm GMT) according to Djoko Murjatmodjo, Indonesia's acting director general of transportation. He says that the pilot "asked to avoid clouds by turning left and going higher to 34,000 feet (10,360 metres)". Airline pilots do attempt to avoid flying over thunderstorm storm clouds, as a safety precaution.
The final potential cause of the flight's disappearance is human error causing the crash. Little is known about the flight's pilots – named by local media as Captain Irianto and its French first officer Remi Emmanuel Plesel – other than they were experienced pilots: Irianto has 6,100 flying hours and Plesel 2,275.
So until a full accident investigation can be completed, including examining any wreckage, witness statements and data from flight 8501's flight recorders – the infamous 'black boxes' – the precise cause of this plane's disappearance will remain a mystery.