Key developments in Malaysia Airlines Flight MH370 search

Investigators are desperately searching for Malaysia Airlines Flight MH370, the jetliner that dropped off the radar shortly after takeoff from Kuala Lumpur on March 8.

Where did the plane go? What happened after contact was lost over the Gulf of Thailand? And why?

An international operation, involving personnel and equipmentfrom at least 25 countries,is working to unravel these mysteries.

The search has been fruitless to date, plagued by false leads and contradictoryinformation.Frustrations are mounting as days pass without a trace of the plane.

Investigators believe the plane's flight path was deliberately altered.Suspicionhas fallen on anyone aboard the plane with aviation experience, particularly the pilot and co-pilot.

Here are some of the key developments in the investigation to date.

Expanding search area

Immediately after the plane was reported missing, the operation was focused on a 50-nautical-mile (93-kilometre) radius around the point of its last contact with civilian radar. That was expanded to 100 nautical miles (186 km) over the next two days.

After possible reports the plane may have reversed course and headed back west, the search was expanded to include land on the Malay Peninsula and the Strait of Malacca between Malaysia and Indonesia.

That search was extended north to the strait to theAndaman Sea. Indiajoined the operation near its remote Andaman and Nicobar islands, then later temporarily halted its involvement.

As of March 13, an area of92,000 square kilometresroughly the size of Portugal was being searched.

Two days later, investigators announced that the search focus had changed dramatically. A satellite reading of the plane, taken seven hours after its last confirmedcontact with civilian radar, showed it was somewhere over one of two large arcs.

A northerncorridor over land now extends up to Kazakhstan while a southern sea corridor extends into the southern Indian Ocean. The total search area stretches over 10,000 kilometres.

Debris sightings and eyewitness accounts

No debris was found near where contact was lost on March 8.Vietnamese air force planesspotted two large oil slicks in the area, but these were later tested and found to be unrelated to the disappearance.

A rectangularobject was spotted on March 9that was thought to be one of the missing plane's doors.Six planes and seven ships from Vietnam searched for that object but nothing has beenfound.

A Singaporean search plane spotted a yellow object on March 10. At first it was thought to be a life-raft,but it turned out to be sea trash.

Chinese satellite images taken on March 9 showed"three suspected floating objects" of varying sizes in a 20-kilometreradiusoff the southern tip of Vietnam.

Further searches showed nothing in the area. The Chinese Embassy later notified the Malaysian government that the images were released by mistake and did not show any debris.

A oil rig worker from New Zealand came forward to sayhe saw a plane going down in flames over the South China Sea in the same time frame as the MH370's disappearance. His account is unconfirmed.

Confusion over radar signals

The plane dropped off civilian radar systems around 1:22 a.m. local time on March 8. What happened next has been extremely unclear, given contradictory reports from military and civilian sources.

A senior military official said on March 11 that theMalaysian military hadradar data showing the jetliner changed course and made it to the Malacca Strait. The plane was believed to be flying lower than its original 11,000-metre altitude.

The map below shows three other radar sightings and officialcomments about the plane, which are either unconfirmed or have been retracted.

1. Malaysia Airlines speculated on March 11 that the plane may have reversed course and was heading back to Subangskypark, an airport about 30 to 40 km north of Kuala Lumpur International Airport.

2. A local newspaper quoted Malaysia's air force chief, Rodzali Daud,as saying radar at a military base had detected the airliner at 2:40 a.m. local time nearPulauPerakat the northern approach to the Strait of Malacca. He later denied this report.

3.Daud said on March 12 that an unidentified object appeared on military radar records about 320kilometres northwest ofPenang, Malaysia. Experts are analyzing the report, taken at 2:15 a.m. on the night of the disappearance,to determine whether the blip is indeed the missing plane.

To complicate things even further, aMarch 13media report quoted U.S. investigators as saying they suspected the plane remained in the air for about four hours after its last confirmed contact, citing data from the plane's engines.

Malaysia's defence minister said the engine manufacturers saidthe last engine data was received at 1:07 a.m. local time, around 15minutes before the plane lost contact. But he did not rule out the report.

On March 13, Reuters news agency reported that sources close to the investigation said military radar-tracking evidence appeared to suggestthe plane was intentionally diverted across the Malay peninsula towards the Andaman Sea.

"What we can say is we are looking at sabotage, with hijack still on the cards," said one of the sources, a senior Malaysian police official.

Passengers and pilots

Shortly after the plane went missing, authorities said that two passengershad boarded using stolen passports, prompting fears of a link to terrorism.

Malaysianpolice lateridentified oneasPouriaNourmohammadi Mehrdad, a 19-year-old Iranianlikely planning to migrate to Germany.Interpol identified the second man asSeyedMohammedRezaDelavar, a 29-year-old Iranian.

Police do not think the pair are tied to any terrorist group.

Chinese officials saidthey have found no links to terrorism among the Chinese citizens on board the plane.

Malaysia Airlines on March 11 refuted a report that five passengers had checked into the flightbut did not board, raising the issue of potential unaccompanied baggage on the plane. The airline said four people with tickets did not show up for the flight, but also did not check in.

The airline also refused to comment on an Australian television report that the co-pilot on flight MH370had previously invited two women into the cockpit during an hour-long flight from Kuala Lumpur to Phuket, Thailand.

As the days passed, the cockpit crew hasbecome a central focus of the investigation.

Malaysian police confiscated a flight simulator from the pilot'shome on March 15and also visited the home of the co-pilot in whatMalaysia's police chiefinitially said was the firstpolice visits to those homes.

(The governmentissued a statement two days latercontradictingthat account by saying police first visited the pilots' homes asearly as March 9, the day after the flight.)

Malaysia Airlines' chief executive says that the co-pilot said the final words heard from the cockpit on March 8: "All right, good night."

Sources: CBC News stories, Associated Press, Reuters, AFP