An Air Asia plane carrying 162 passengers and crew has vanished.

155 passengers, 17 of them children, and seven crew are on board the aircraft.

The aircraft was travelling from Indonesia to Singapore when it lost contact with air traffic control.

It's thought the pilot asked to change course to avoid bad weather.

A major search and rescue operation's underway to try to find it.

Aviation expert Doug MacLean says whatever happened, it seems to have been sudden.