Dec 29 (Reuters) - Uncertainties surround the deadliest

crash on South Korean soil, experts said on Sunday, questioning

initial suggestions that a bird strike might have brought down

Jeju Air flight 7C2216.

The apparent absence of landing gear, the timing of the

twin-engine Boeing 737-800's belly-landing at Muan

International Airport and the reports of a possible bird strike

all raised questions that could not yet be answered.

The single-aisle aircraft was seen in video broadcast on

local media skidding down the runway with no visible landing

gear before slamming into a wall in an explosion of flame and

debris.

"Why didn't fire tenders lay foam on the runway? Why weren't

they in attendance when the plane touched down? And why did the

aircraft touch down so far down the runway? And why was there a

brick wall at the end of the runway?" said Airline News editor

Geoffrey Thomas.

South Korean officials said they were investigating the

cause of the crash, including a possible bird strike, which

killed almost all the 181 people on the aircraft.

The flight data recorder was found at 11:30 a.m. (0230 GMT),

about two and a half hours after the crash, and the cockpit

voice recorder was found at 2:24 p.m., according to South

Korea's transport ministry.

"That gives you all the parameters of all the systems of the

plane. The heartbeat of the airplane is on the flight data

recorder," Thomas said. "The voice recorder will probably

provide the most interesting analysis of what went on on this

tragic crash."

Within a few minutes, the control tower issued a bird strike

warning, pilots declared mayday and then attempted to land,

officials said, although it was not clear whether the aircraft

had hit any birds.

Experts said it seemed unlikely a bird strike would have

caused the landing gear to malfunction.

"A bird strike is not unusual, problems with an

undercarriage are not unusual. Bird strikes happen far more

often, but typically they don't cause the loss of an airplane by

themselves," Thomas said.

Australian airline safety expert Geoffrey Dell said, "I've

never seen a bird strike prevent the landing gear from being

extended."

Australian aviation consultant Trevor Jensen said fire and

emergency services would normally be ready for a belly-landing,

"so this appears to be unplanned".

A bird strike could have impacted the CFM International

engines if a flock had been sucked into them but that would not

have shut them down straightaway, giving the pilots some time to

deal with the situation, Dell said.

It was unclear why the plane did not decelerate after it hit

the runway, Dell and Jensen said.

Typically in a belly landing, "You are going to land on your

engines and you're going to have a bumpy ride," Thomas said.

"You come in with minimum fuel, you have fire tenders in

attendance, covering the runway with foam and you land at the

furthest end of the runway and usually it ends up being an OK

situation."