BEIJING, March 12 -- China sent a third military aircraft on Wednesday to help search for the missing Malaysian plane as the search range expanded to land areas.

The aircraft, sent by the Chinese air force, will join the two aircraft sent on Tuesday to probe for black-box signals above waters suspected to be the site of the missing jet, according to a military spokesman.

The plane has been missing for over four days since contact with it was lost early on Saturday. It was flying over the Ho Chi Minh air traffic control area in Vietnam and carrying 227 passengers, including 154 Chinese.

As of late afternoon on Wednesday, eight Chinese vessels, including three warships, have arrived and are conducted operations in the waters, without finding debris or objects from the plane. More ships are expected to reach the waters.

Dozens of vessels and aircraft from various countries have also joined the search. Vietnam's military said that it would also conduct searching on land areas along two flight routes.

Meanwhile, China has employed 10 satellites to provide technological support in attempts to locate the missing Boeing 777-200, which was expected to land in Beijing at 6:30 a.m. local time on Saturday.