Why a Malaysia 737 suffered uncommanded pitch up

A preliminary report issued by the Civil Aviation Authority of Malaysia (CAAM) has determined that a Malaysia Airlines (MAS) Boeing 737-800 unexpectedly pitched up after the aircraft’s pitot-static system indicated a false speed. The crew elected to return to their departure airport – Kuala Lumpur International – following the incident. The eight-year-old narrowbody, 9M-MLS (c/n 39333), was operating flight MH 2664 between the airline’s Kuala Lumpur base and Tawau on the island of Borneo - at an approximate route distance