Naval vessels in the southern Indian Ocean were in a race against time Sunday after Australian authorities said electronic signals detected by a Chinese ship involved in the search for missing Malaysia Airlines Flight 370 were consistent with an aircraft black box.  However, retired Australian Air Chief Marshall Angus Houston stressed the two electronic pulses reported on Friday and Saturday had not been verified as being connected to the missing jet, which disappeared from radar screens and lost contact with air traffic controllers early on the morning of March 8.  "This is an important and encouraging lead, but one which I urge you to treat carefully," Houston told reporters in Perth Sunday.  Houston also confirmed a report by China's official Xinhua News Agency that the patrol vessel Haixun 01 had detected a "pulse signal" at 37.5 kilohertz (cycles per second) -- the same frequency emitted by flight data recorders aboard the missing plane -- in the search area in the southern Indian Ocean Saturday.  Houston also said Haixun 01 had detected a signal again on Saturday within 1.4 miles of the original signal, for a period of 90 seconds. He said that China also reported seeing white objects floating in the sea in the area.  Houston said the British navy's HMS Echo, which is fitted with sophisticated sound locating equipment, is moving immediately to the area where the Haixun 01 detected the signals. The Australian navy's Ocean Shield, which is carrying high-tech sound detectors from the U.S. Navy, will also travel to the area.  But Ocean Shield would first investigate a sound it had picked up from the deep ocean in a different region, he said.  He said Australian air force assets were also being deployed on Sunday into the Haixun 01's area.  The effort would work on "discounting or confirming the detections," he said.  After weeks of fruitless looking, the multinational search team is racing against time to find the sound-emitting beacons and cockpit voice recorders that could help unravel the mystery of the plane. The beacons in the black boxes emit "pings" so they can be more easily found, but the batteries only last for about a month.  Malaysia Airlines Flight 370 was en route from Kuala Lumpur to Beijing when it vanished, and investigators believe it veered way off course and came down somewhere in the southern Indian Ocean, though they have not been able to explain why it did so.  The Associated Press contributed to this report.
China's official news agency says a Chinese ship that is part of the multinational search effort looking for the missing Malaysia Airlines plane has detected a pulse signal in southern Indian Ocean waters.