Malaysia Airlines flight MH370 took off from Kuala Lumpur almost four weeks ago. Despite an intense international search no trace of the plane has been found.
So what do we know?
Here is a timeline with some of the key events of the last four weeks surrounding this aviation mystery:
March 8 2014: Malaysian Airlines flight MH370 takes off from Kuala Lumpur at 12.41am local time bound for Beijing carrying 227 passengers and 12 crew.
The last communication from the cockpit comes at 1.19am and the plane is last seen on military radar at 02.14am heading west over the Strait of Malacca.
Half an hour later the airline reveals to the public it has lost contact with the plane. The plane was due to land around 6.30am.
Officials reveal two passports used to board the flight were stolen, raising the first suspicions of terrorist involvement.
March 9 2014: Malaysia's air force chief says that military radar indicated the missing Boeing 777 jet may have turned back.
March 10 2014: Vietnamese aircraft search for a plane door spotted in their waters but find nothing.
March 11: The hunt is widened to cover a 115-nautical mile radius involving 34 aircraft and 40 ships from several countries.
The two male passengers travelling with stolen passports were Iranians who had bought tickets to Europe and were probably not terrorists, Malaysian police say.
March 12: Satellite images on a Chinese government website show suspected debris from the missing plane floating off the southern tip of Vietnam, China's Xinhua News Agency says.
The report includes co-ordinates of a location in the sea off the southern tip of Vietnam and east of Malaysia, near the plane's original flight path.
March 13: Malaysian authorities expand their search for the missing jet into the Andaman Sea and beyond after acknowledging it could have flown for several more hours after its last contact with the ground.
Nothing is found when planes are sent to search an area off southern Vietnam identified by Chinese satellite images. The Chinese Embassy notifies the Malaysian government that the images were released by mistake and do not show any debris from the missing flight.
March 15: Malaysian prime minister Najib Razak says the missing airliner was deliberately diverted and continued flying for more than six hours after losing contact with the ground. The plane could have gone as far north west as Kazakhstan or into the Indian Ocean's southern reaches.
Malaysian police say they are looking at the psychological state, family life and connections of pilot Zaharie Ahmad Shah, 53, and co-pilot Fariq Abdul Hamid, 27. Both have been described as respectable, community-minded men.
March 16: The search area now includes 11 countries the plane might have flown over. The number of countries involved in the operation have increased from 14 to 25.
Malaysian defence minister Hishammuddin Hussein says he has asked governments to hand over sensitive radar and satellite data to try to help get a better idea of the plane's final movements.
March 17: Officials release a new timeline suggesting the final voice transmission from the cockpit of the missing Malaysian plane may have occurred before any of its communications systems were disabled.
Investigators have not ruled out hijacking, sabotage, or pilot suicide, and they are checking the backgrounds of the 227 passengers and 12 crew members, as well as the ground crew, to see if links to terrorists, personal problems or psychological issues could be factors.
March 18: Thailand's military says it saw radar blips that might have been from the missing plane but did not report it ''because we did not pay attention to it''.
March 19: Distressed relatives of the missing passengers threaten to go on hunger strike over the lack of information about the investigation.
March 20: Two objects which could be connected to the missing jet are detected in the southern India Ocean, the Australian prime minister Tony Abbott says.
Four military search planes are dispatched to the area.
Mr Hussein cautions against jumping to conclusions, but tells a press conference the sighting is a ''credible lead''.
The Ministry of Defence (MoD) announces that survey ship HMS Echo is being sent to help with the search.
March 21: China sends three warships to join the search in the southern Indian Ocean, it is announced.
March 22: A Chinese satellite spots a large object along a broad stretch of ocean where officials hope to find the plane, it is announced by Mr Hussein.
March 23: Planes and ships are scrambled to find a pallet and other debris in the southern Indian Ocean as the search resumes.
Relatives of the passengers on board the flight grow increasingly angry over the lack of information about the fate of their loved ones.
France says it has picked up satellite images of objects in a remote patch of the southern Indian Ocean.
March 24: Chinese and Australian planes spot several objects in an area identified by multiple satellite images as containing possible debris from the missing airliner.
Mr Razak makes the announcement that Flight MH370 has ended in the southern Indian Ocean, based on new analysis by the UK Air Accidents Investigation Branch and tracking firm Inmarsat.
March 27: A French satellite spots more than 120 objects in the Indian Ocean but search for them proves unsuccessful.
March 28: Air crews begin searching new area of the Indian Ocean after new radar data analysis suggests the jet flew faster than originally thought.
March 30: Several dozen Chinese relatives of passengers stage demonstration in Kuala Lumpur holding up banners reading: "We want evidence, truth, dignity."
April 1: Malaysian authorities release their full transcript of audio communications between the cockpit and air traffic controllers before the plane disappeared.
This includes slight change in final words recorded at 1.19am which now read "Good night Malaysian Three Seven Zero".
Royal Navy survey ship HMS Echo joins Royal Navy submarine HMS Tireless in the search.
April 3 Angus Houston, the head of a joint agency co-ordinating the search, says there is no time
frame for ending the search, but acknowledges a new approach will eventually be needed if nothing turns up.
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