AirAsia Flight 8501 plunged into the Java Sea on December 28 shortly after the pilots asked to climb from 32,000 feet to 38,000 feet to avoid threatening clouds, but were denied permission because of heavy air traffic. No distress signal was received. The plane was en route from Surabaya, Indonesia's second-largest city, to Singapore.
"There is no sign of sabotage in the AirAsia crash," National Transportation Safety Committee head Tatang Kurniadi told reporters.
He said investigators have downloaded all of the data from the aircraft's cockpit voice recorder and flight data recorder and are analysing them along with advisers from Airbus, the plane's manufacturer.
Transport Minister Ignasius Jonan told Parliament yesterday that radar data showed that the plane was climbing at an abnormally high rate - about 6,000 feet a minute - then dropped rapidly and disappeared.
He did not say what caused the plane to climb so rapidly.
An excessively rapid ascent is likely to cause an airplane to go into an aerodynamic stall.