*

Data could be crucial to determining cause of crash on

Dec. 29

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Crash killed 179 people, the worse on South Korean

territory

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Black boxes record communications data and aircraft

systems

performance

(Add background, context and analyst comments throughout)

By Hyunjoo Jin and Jack Kim

SEOUL, Jan 11 (Reuters) - The two black boxes on the

Boeing ( BA ) jet involved in the worst aviation disaster on

South Korean soil stopped recording about four minutes before

the accident, the transport ministry said on Saturday.

South Korean investigators previously said the flight data

and cockpit voice recorders were key to finding out the cause of

last month's crash that killed 179 people.

It happened about four minutes after the pilot of the

airliner operated by Jeju Air reported a bird

strike.

Authorities investigating the crash plan to analyse what

caused the black boxes to stop recording, the ministry said in a

statement.

The voice recorder was initially analysed in South Korea,

and, when data was found to be missing, sent to a U.S. National

Transportation Safety Board laboratory, the ministry said.

Black box recorders collect data on communications involving

pilots in the cockpit as well as how the aircraft systems

perform in-flight.

Jeju Air 7C2216, which departed the Thai capital Bangkok for

Muan in southwestern South Korea, belly-landed and overshot the

regional airport's runway on Dec. 29, exploding into flames

after hitting an embankment. Only two people survived - crew

members who were sitting in the tail section.

Two minutes before the pilots declared a Mayday emergency

call, air traffic control gave caution for "bird activity".

Sim Jai-dong, a former transport ministry accident

investigator, said the discovery of the missing data from the

budget airline's Boeing 737-800 jet's crucial final minutes was

surprising and suggests all power, including backup, may have

been cut, which is rare.

The transport ministry said other data available would be

used in the investigation and that it would ensure the probe is

transparent and that information is shared with the victims'

families.

Some members of the victims' families have said the

transport ministry should not be taking the lead in the

investigation and that it should involve independent experts,

including those recommended by the families.

The investigation has also focused on the embankment the

plane crashed into, which was designed to prop up a "localiser"

system used to assist aircraft landing, including why it was

built with such rigid material and so close to the end of the

runway.