The search for Malaysia Airlines flight MH370 has entered its fourth week, with the plane believed to have crashed in the southern Indian Ocean, thousands of miles from its original flight path.
Just as the batteries on the locator beacons on the aircraft's "black boxes" are nearing their limits, the searchers have detected signals they believe are "consistent" with the flight recorders.
Australian authorities said the signals may represent the best lead yet after the international investigation into the ill-fated carrier was initially stymied by several false leads.
Many questions about the fate of MH370, which left Kuala Lumpur en route to Beiing on March 8 with 239 passengers and crew, remain unanswered, including why the flight diverted from its planned route and what exactly caused it to crash.
The lack of information has taken a toll on the families of those on board the flight who until the announcement had been clinging on to hope their relatives may still be alive.
Here is a chronology of the latest developments:
Signals picked up by a black-box detector attached to an Australian ship were consistent with aircraft flight recorders, Australian officials said.
Two signals have been detected off the northwest coast of Australia, with the first held for 2.5 hours before contact was lost and the second for around 13 minutes. Confirmation of whether the signals are related to the missing flight could take several days, said Angus Houston, who is heading the Australian agency coordinating the search.
While the signals are about 300 nautical miles away from the location where a Chinese patrol ship detected a signal earlier in the week, but authorities noted that sound can travel great distances in deep water.
A Chinese patrol ship detected a pulse signal in the south Indian Ocean, according to a report from state-owned news agency Xinhua. Both Xinhua and Australian search authorities said the signal was "consistent" with a black box, but noted there was no conclusive evidence linking the signal to Flight MH370.
Malaysia released the full transcript of communications between MH370 and air traffic control before the flight dropped off of civilian radar. The last words were "good night, Malaysian three seven zero," Malaysian authorities said. Previously, authorities had said the last communication was "all right, good night."
"There is no indication of anything abnormal in the transcript," Hishammuddin Hussein, Malaysia's acting transport minister, said.
The search area was shifted closer to Australia after further analysis of satellite data suggested the plan may have been traveling faster than earlier estimates, possibly running out of fuel sooner than previously believed.
Chinese relatives of passengers stage a protest in Kuala Lumpur to demand the Malaysian government apologize for its handling of the search and for the prime minister's statement claiming the flight ended in the Indian Ocean.
Tuesday, March 25
Search suspended: Search operation for wreckage of the flight is temporarily suspended due to poor weather conditions in the southern Indian Ocean.
Monday, March 24
Confirmation of flight's fate:Malaysian Prime Minister Najib Razak says fresh analysis of satellite data tracking MH370 shows the flight went down with passengers and crew members in the southern Indian Ocean, west of Perth - a remote location, far from any possible landing sites.
Informing relatives: Malaysia Airlines sends text messages to families saying it has to be assumed that that none of those on board MH370 survived. The airline says arrangements will be made to take relatives of passengers to the recovery area once it receives approval from the investigating authorities.
More debris spotted: Earlier in the day, a Chinese plane spotted two white, square-shaped objects in an area identified by satellite imagery as containing possible debris from the missing airline.