The Navy on Thursday began switching out the P-3 Orion surveillance aircraft for a more modern P-8 Poseidon in the hunt for missing Malaysian Airlines Flight 370.
The P-3 returned to Kadena Air Base on Okinawa and was replaced by a P-8 Poseidon that will operate from the main search base in Perth, Australia, said Rear Adm. John Kirby, the Pentagon press secretary.
The Navy has also sent a pinger locator system and an unmanned submersible to Perth but they will not be deployed until search aircraft and ships can pinpoint evidence of a debris field, according to the Navy's 7th Fleet.
Satellite images provided by several nations and defense firms have shown what could be debris from the Boeing 777 in the same general area about 1,500 miles off Australia's west coast, but none of the objects has been recovered to provide definitive proof.
The search aircraft were grounded by bad weather Thursday but were expected to fly again Friday. A total of 11 search aircraft from several countries and five ships were engaged in the hunt. Kirby said there were no immediate plans to send a Navy ship to join the search.
The Malaysian flight from Kuala Lumpur to Beijing was carrying 239 people when it went missing more than two weeks ago.
Earlier this week, Kirby said that the Navy's TPL-25 Towed Pinger Locator System and a Bluefin-21 underwater drone had been sent to Perth along with 10 personnel to operate the systems.
Both systems will be loaded aboard the Australian ship Seahorse Standard when a debris field is found, Kirby said.
The Pinger Locator can detect pings from the aircraft's black boxes at depths up to 20,000 feet, the Navy said. The Bluefin-21 "has side-scanning sonar and what we call a multibeam echo sounder," Kirby said.
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