A train carrying 282 bodies from Malaysia Airlines Flight 17 arrived in Kharkiv, Ukraine, getting the bodies one step closer to their grieving families around the world.
The train arrived at a rail station and continued on to an undisclosed location. The bodies will eventually be taken to the Netherlands.
But a litany of obstacles remain - not just in handling the remains, but in figuring out how and why MH17 was shot down over eastern Ukraine.
See more on this developing story on CNN.com.
In a sea of uncertainty, two bits of good news emerged Wednesday.
Searchers picked up fresh signals that officials hope are locator beacons from the data recorders of the missing Malaysia Airlines Flight 370.
The Australian ship Ocean Shield had first picked up the underwater pulses Saturday. But then, for the next three days, nothing.
On Tuesday, the ship once again reacquired the signals. That's four signals in the same broad area: two on Saturday; two on Tuesday. All of the signals are within 17 miles of one another.
"I believe we are searching in the right area, but we need to visually identify wreckage before we can confirm with certainty that this is the final resting place of MH370," said Air Chief Marshal Angus Houston, who's coordinating the Australian operation.
The second piece of good news? Authorities analyzed the signals picked up Saturday and determined they weren't natural occurrences, but likely came from specific electronic equipment. Some marine life make similar sounds.
"They believe the signals to be consistent with the specification and description of a flight data recorder," Houston said. "I'm now optimistic. We'll find the aircraft or what's left of the aircraft in the not too distant future."
Signals getting weaker
Wednesday is Day 33 in the search for Malaysia Airlines Flight 370, which went missing March 8. It was carrying 239 people.
Authorities haven't given up trying. Instead, they are pinning their hopes on the pings.
But time is not on their side.
The batteries powering the flight recorders' locator beacons are certified to be working for 30 days. Stored in a plane's tail, they are designed to begin sending off distinct, high-pitched signals as soon as they come in contact with water.
"The signals are getting weaker. Which means we're either moving away from the search area or the pinger batteries are dying," Houston said.
The first signal, at 4:45 p.m. Perth Time on Saturday, lasted 2 hours 20 minutes.
The second, at 9:27 p.m. Saturday, lasted 13 minutes.
The third signal was picked up Tuesday at 4:27 p.m. That lasted 5 minutes 32 seconds.
The fourth, at 10:17 p.m. Tuesday, was 7 minutes long.
"It's certainly encouraging that more signals have been detected," Pentagon spokesman Adm. John Kirby told CNN. "There is still much work to do, however."
U.S. Navy Capt. Mark Matthews did not join the speculation over the new signals, instead sticking to the black and white world of science.
"I'm an engineer so we don't talk emotions too much," he said.
Matthews is overseeing the American equipment being used aboard the Ocean Shield to pick up the signals.
Scouring for debris
There's still no indication of wreckage from the plane. And so the visual search goes on.
Wednesday's effort includes up to 11 military planes, four civilian aircraft as well as 14 ships. Three of them - the Ocean Shield farther north, and the British HMS Echo and Chinese Haixun 01 to the south - will be focusing underwater.
All told, everyone involved will be scouring a 29,000-square-mile zone centered about 1,400 miles northwest of Perth.
That's roughly the size of South Carolina.
But it still pales in comparison to the once nearly 3 million miles, at sea and on land, the searchers were scouring for signs of the lost aircraft a few weeks ago.
Kevin McEvoy, a New Zealand air force commodore involved in the effort, noted that authorities once "didn't even know which haystack" to look in for the aircraft.
"I think we have got a much clearer picture around the areas that we need to concentrate on," McEvoy told CNN's Erin Burnett from Auckland.
Authorities greatly reduced that area after analyzing satellite data to determine Flight 370 had set off from Kuala Lumpur toward Beijing, turned around to go back over the Malay Peninsula, then ended up in the southern Indian Ocean.
Why? No one really knows.
The best chance to answer that question may rest wherever the plane - and its so-called black boxes, with their trove of information about the plane and its movements - now resides.
Search planes dispatched day after day looking for evidence of the missing airliner - a floating wing, a seat cushion, anything - thus far have come up empty.
The latest, greatest hopes have come from crews listening underwater for signs of Flight 370.
The ocean to contend with
The first such possible breakthrough came last Friday and Saturday, when a Chinese ship detected pulses that may have been from the plane. No more have been heard since.
According to McEvoy, "the main focus" centers around the site of Ocean Shield's discovery. The ship used more advanced detection gear than that aboard the Chinese vessel and was found some 375 miles away, leading Houston to believe they are separate signals.
Beyond the dwindling battery life, there's all the ocean to contend with: The Ocean Shield signals were in water about 2.6 miles deep, meaning a number of things could literally get in the way of or otherwise disrupt the pulses.
To make sure the waters in the area isn't roiled any further, air and sea traffic there is being limited. That's why there's no rush to put in underwater drones to take photos.
Ocean Shield can search six times the amount of area with a towed pinger locator than can be done with the sonar on a drone, Houston said.
"The better the Ocean Shield can define the area, the easier it will be for the Autonomous Underwater Vehicle to subsequently search for aircraft wreckage," he said. "Bear in mind with the Air France disaster, it took the underwater vehicle 20 days to get to the wreckage."
A painstaking process
If more pulses are detected, it's not as if they'll lead down in a straight line to the flight recorders. As is, the pings that were heard could have emanated from anywhere within a 5-mile radius, said Mary Schiavo, a former inspector general for the U.S. Department of Transportation.
Finding more signals could narrow the search area. Without them, authorities could then start the painstaking process of using side-scanning sonar to try to find the aircraft on the ocean's bottom.
The absence of wreckage near these detected signals leaves some skeptical, worried that the Chinese and Australian ship's finds could be yet another false lead in an investigation that's been full of them.
Acknowledging "a very high-speed vertical impact" could explain the lack of aircraft remnants, CNN aviation analyst Miles O'Brien said there's reason to be cautious.
"It's either the most extraordinary event, or those pings weren't real," O'Brien said. "It's somewhat befuddling."
Sarah Bajc, the partner of American passenger Philip Wood, isn't convinced about anything. She told CNN's Erin Burnett she thinks the plane was hijacked.
"All of us pretty well agree that until there's the bulk of the plane, the bulk of the bodies discovered, and a black box intact, we won't believe that it's final evidence," Bajc said early Wednesday from Beijing. "I don't think the authorities have given us much confidence of their investigative skills so far."
The lack of clarity makes it hard to "grieve properly and ... move on" - something that she's not yet willing to do.
"I want to fight to find him, in whatever form that ends up being," said Bajc, who is coordinating with other passengers' kin to press for answers. "And I think most of the families feel the same way."
Until they get answers, family members like Steve Wang are clinging to hope while trying to hold themselves together. His mother was on the plane.
"We're just going through so many kinds of emotion," Wang said. "Desperate, sad and helpless - something like that. Everything."
After weeks of searching vast swaths of ocean, investigators now have their "most promising" lead yet in finding Malaysia Airlines Flight 370.
A pinger locator in the Indian Ocean has detected signals consistent with those sent by a flight data recorder and a cockpit voice recorder, the head of the Australian agency coordinating search operations said Monday.
The sounds were heard at a depth of 4,500 meters (about 14,800 feet), retired Air Chief Marshal Angus Houston said.
"We've got a visual indication on a screen, and we've also got an audible signal. And the audible signal sounds to me just like an emergency locator beacon," Houston said.
"We are encouraged that we are very close to where we need to be."
But it could take days before officials can confirm whether the signals did indeed come from the plane, which fell off the radar on March 8 with 239 people on board.
"In very deep oceanic water, nothing happens fast," Houston said. "I would ask all of you to treat this information cautiously and responsibly. ... We haven't found the aircraft yet."
At least one investigator has described the search not as finding a needle in a haystack, but rather trying to find the haystack.
"It's very exciting, very exciting," forensic audio expert Paul Ginsberg said Monday. "I think we have finally found the haystack."
And Malaysian authorities are hopeful there will be a positive development in the next few days, if not hours, acting Transportation Minister Hishammuddin Hussein told reporters Monday.
But some relatives of those on board haven't lost hope, despite Monday's news of the promising signals.
"If the plane is there, its there. We can't change it," the husband of one passenger said. "But I am still hoping for a miracle to happen."
But time could be running out in tracing the sounds. In a few hours or days, the pingers aboard the plane stop transmitting for good.
The batteries inside the beacons, which are designed to start sending signals when a plane crashes into water, last about 30 days after the devices are activated.
Monday marks the 31st day of the search.
What happens after the Malaysian plane's pingers die?
New flight details
While searchers may be getting closer to the plane itself, a fresh mystery has emerged about what happened during the flight.
The aircraft skirted Indonesian airspace as it went off the grid and veered off course, a senior Malaysian government source told CNN on Sunday.
After reviewing radar track data from neighboring countries, officials have concluded that the plane curved north of Indonesia before turning south toward the southern Indian Ocean, the Malaysian source said.
Whoever was flying the plane, the source said, could have been trying to avoid radar detection.
Like most details in the case that's baffled investigators ever since the plane dropped off Malaysian military radar, it depends on whom you ask.
CNN law enforcement analyst Tom Fuentes cautioned against assuming a nefarious reason for steering the plane around Indonesia's airspace.
"I think the plane's being intentionally flown there, but I think it's still a mystery as to why. ... I think they would probably guess they're not avoiding anybody's radar, because there's a lot of radar in the area," he said. "I think they're avoiding getting shot down or colliding with another airplane."
CNN aviation analyst Miles O'Brien said the new route includes designated waypoints that pilots and air traffic controllers use.
"This particular route that is laid out happens to coincide with some of these named intersections," he said. "So what it shows is an experienced pilot somewhere in the mix on this."
Investigators haven't said who they think might have flown the plane off course or why.
But Hussein, Malaysia's acting transportation minister, said Monday that Indonesian military authorities told the chief of the Malaysian defense force that they had "no sighting" of the plane the night it disappeared.
The possibility that the plane was hijacked by someone who knew how to fly a commercial jet is still on the table. Authorities have also been investigating the plane's captain and co-pilot. And they haven't ruled out mechanical problems as a possible cause of the plane's diversion.
So far, no physical evidence of the plane's eventual whereabouts has been found, leaving many relatives of those on board trapped in uncertainty.
The HMS Echo, a British navy ship equipped with advanced detection gear, sailed into the area of the southern Indian Ocean on Monday morning (Sunday afternoon ET) where a Chinese crew had detected two audio signals.
The area of detection is roughly 1,600 kilometers (1,000 miles) west-northwest of Perth, according to coordinates reported by Chinese state media.
The arrival of the Echo will be critical to the search for the missing Boeing 777. It has state-of-the-art sonar and is capable of mapping the ocean floor, which is about 4,500 meters (2.8 miles) deep in the focused search area.
It should be able to help determine more confidently whether audio signals picked up on Friday and Saturday by the Chinese patrol ship Haixun 01 came from the plane.
The Chinese said the electronic pulses - detected only 2 kilometers (1.25 miles) apart - were consistent with those emitted by pingers on an aircraft's black boxes.
Sounds travel long distances underwater, Houston said, making it difficult to ascertain their sources. If detectors were near a pinger, they would pick up the signal for a more sustained period.
Houston also said that search authorities were informed Sunday that the Ocean Shield, an Australian naval vessel equipped with sophisticated listening equipment, has detected "an acoustic noise" in another area of the ocean to the north.
'Most promising lead'
The Ocean Shield, which has a high-tech pinger locator borrowed from the U.S. Navy, will continue to pursue the sound it heard. If that lead turns cold, it will move to the other detection area, a journey that will take at least a day, officials said.
On Monday morning, the Ocean Shield was "continuing investigations in its own area," Australian authorities said.
"At the moment, the most promising lead appears to be the one associated with Haixun 01," Houston said.
The pulses registered by the Chinese ship are of particular interest because they occurred in an area that fits with the latest calculation by experts of roughly where the plane is likely to have entered the water, Houston said.
The hunt for Malaysia Airlines Flight 370 has penetrated beneath the waves as searchers race to catch pings from the missing plane's flight data recorders before they fall silent.
But the area of the southern Indian Ocean where British and Australian naval ships are deploying sophisticated listening technology remains nothing more than an educated guess at where the plane may have hit the water.
The British Royal Navy survey ship HMS Echo and the Australian naval supply ship Ocean Shield began searching the ocean's depths along a single 240-kilometer (150-mile) track Friday, said retired Air Chief Marshal Angus Houston, the head of the Australian agency coordinating the search efforts.
The Ocean Shield is equipped with high-tech gear borrowed from the United States: the TPL-25, a giant underwater microphone that will listen for the pings from the flight data recorders, and the Bluefin-21, an underwater robot that can scour the ocean bed for signs of wreckage. The HMS Echo also has advanced sensor equipment.
Time is running out in the efforts to detect the pings as the batteries that power the recorders' beacons are expected to expire in the coming days.
"If they do find it, I think it'll be remarkable," said Bill Schofield, an Australian scientist who worked on developing flight data recorders.
Nearly four weeks have passed since the jetliner vanished with 239 people on board. With investigators still apparently stumped by the case, information in the flight recorders could help them unravel the mystery of what happened the night the plane dropped off radar.
But there are no new clues behind the area where the underwater search is concentrated. It's based on the same kind of analysis of radar, satellite and other data that investigators have used to determine a series of shifting search areas in recent weeks.
"The area of highest probability as to where the aircraft might have entered the water is the area where the underwater search will commence," Houston said at a news conference Friday. "It's on the basis of data that arrived only recently, and it's the best data that is available."
They were words heard around the world as investigators searched for the missing Malaysia Airlines plane.
Weeks ago, Malaysian authorities said the last message from the airplane cockpit was, "All right, good night."
The sign-off to air traffic controllers, which investigators said was spoken by the plane's copilot, was among the few concrete details officials released in a mystery that's baffled investigators since the Boeing 777 disappeared with 239 people aboard on March 8.
There's only one problem. It turns out, it wasn't true.
On Tuesday, Malaysia's Transport Ministry released the transcript of the conversations between the Flight 370's cockpit and air traffic control. The final words from the plane: "Good night Malaysian three seven zero."
Malaysian authorities gave no explanation for the discrepancy between the two quotes. And authorities are still trying to determine whether it was the plane's pilot or copilot who said them.
The final quote is routine and is not a sign that anything untoward occurred aboard the flight, said CNN aviation analyst Mary Schiavo.
But the change in wording weeks into the search for the missing plane raises questions about how Malaysian officials have handled the investigation.
"It speaks to credibility issues, unfortunately," Schiavo said.
"We haven't had a straight, clear word that we can have a lot of fidelity in," said Michael Goldfarb, former chief of staff at the U.S. Federal Aviation Administration. "We have the tragedy of the crash, we have the tragedy of an investigation gone awry and then we have questions about where we go from here."
Malaysian authorities have defended their handling of the situation.
Acting Transportation Minister Hishammuddin Hussein said Monday that authorities were not hiding anything by declining to release some details of the missing flight. Some details are part of ongoing investigations into what happened to the plane, he said.
"We are not hiding anything," he said. "We are just following the procedure that is being set."
Hussein said the transcript released Tuesday offered "no indication of anything abnormal."
Potential leads on the missing Malaysian jetliner keep coming. So do the setbacks and frustrations.
Four orange objects spotted by aircraft searching for the plane in the treacherous Indian Ocean turned out to be fishing equipment, Australian officials said Monday.
Flight Lt. Russell Adams had described the objects found Sunday as the "most promising leads."
But on further analysis, they turned out to be fishing equipment, once again dashing hopes of finding the jetliner that vanished March 8.
"We are searching a vast area of ocean, and we are working on quite limited information," Australian Prime Minister Tony Abbott told reporters Monday. "Nevertheless, the best brains in the world are applying themselves to this task. ... If this mystery is solvable, we will solve it."
The area of the search is 254,000 square kilometers (98,069 miles) that 10 planes and 11 ships were searching Monday. It's the most vessels to comb the search area so far.
Search crews from various nations have found an array of potential leads, only to later shoot down any links to the missing plane. They've included dead jelly fish and other garbage floating in the southern Indian Ocean.
Race against time
With every passing minute, it becomes harder to find the flight data recorders and cockpit voice recorders. Batteries on the "pinger" - the beacon that sends a signal from recorders - are designed to last about 30 days.
Malaysia Airlines Flight 370 disappeared 23 days ago en route from Kuala Lumpur to Beijing.
An Australian ship fitted with a U.S. ping detector is set to join the search Monday in a desperate race against time.
The focus is on helping find the flight recorders. Find the pinger and you find the recorders. Find the recorders, experts say, and you are steps closer to solving the mystery of Flight 370. Flight data recorders capture a wide array of information, including altitudes, air speeds and engine temperatures.
Crews loaded an American pinger locator and undersea search equipment onto the Ocean Shield, an offshore support vessel of the Australian navy. The ship was originally set to depart Monday morning, but authorities said it would be delayed by several hours for an inspection.
It will take the ship up to three days to reach the search area.
But that's just one of the many hurdles.
Oceanographer Erik Van Sebille weighs in on the possibility of finding the data recorder for Flight 370.
WATCH FULL CLIP ABOVE
Nearly three weeks after the disappearance of Malaysia Airlines Flight 370, the focus of the hunt for the missing passenger jet has moved yet again.
Search teams have shifted to a different part of the southern Indian Ocean after Australian authorities said they received "a new credible lead" about the jetliner's most likely last movements.
An analysis of radar data led investigators to move the search to an area 1,100 kilometers (680 miles) to the northeast of where efforts had been focused previously, the Australian Maritime Safety Authority said Friday.
It described the new information, which indicated the errant jetliner didn't fly as far south as previously thought, as "the most credible lead to where debris may be located."
That means the huge, isolated areas of the ocean that ships and planes had combed for more than a week - and where various satellites detected objects that might be debris from the missing plane - are no longer of interest.
"We have moved on from those search areas," said John Young, general manager of emergency response for the Australian maritime authority.
The new search area is "considerable" and conditions there "remain challenging," acting Malaysian Transport Minister Hishammuddin Hussein told reporters Friday.
The sudden change of geographic focus is the latest twist in an investigation that has so far failed to establish why Flight 370 flew dramatically off course or exactly where the plane and the 239 people it was carrying ended up.
"To me, it's not a game changer, it's a reset," David Gallo of theWoods Hole Oceanographic Institution said of the shifted search.
'We have not seen any debris'
Australian officials also played down the significance of hundreds of possible objects detected by satellites in the previous search region, some of which had been described by authorities as important leads.
"In regards to the old areas, we have not seen any debris," Young said at a news briefing in Canberra, the Australian capital. "And I would not wish to classify any of the satellite imagery as debris, nor would I want to classify any of the few visual sightings that we made as debris. That's just not justifiable from what we have seen."
Officials had repeatedly cautioned that the objects seen in the satellite imagery could just be flotsam that had fallen off cargo ships.
But Hishammuddin said the new search area "could still be consistent" with the idea that materials spotted in recent satellite photos over the previous search area are connected to the plane. The materials could have drifted in ocean currents, he said.
Some analysts raised their eyebrows at the search coordinators' readiness to move away from the satellite sightings.
"Really? That much debris and we're not going to have a look at it to see what that stuff might be?" said Gallo, who helped lead the search for the flight recorders of Air France Flight 447, which crashed into the Atlantic Ocean in 2009.
Others lamented the amount of time, money and resources that were spent sending planes and ships out to the now discounted areas for more than a week.
"This is time that has been wasted, there's no question," said CNN aviation analyst Miles O'Brien.
But Young disputed that suggestion, saying the previous searches were based on the information authorities "had at the time."
"That's nothing unusual for search and rescue operations," he said "And this actually happens to us all the time - that new information may arise out of sequence with the search itself."
A son of the pilot of missing Malaysia Airlines Flight 370 has defended his father, rejecting speculation about his possible role in the plane's disappearance.
"I've read everything online. But I've ignored all the speculation. I know my father better," Ahmad Seth Zaharie, 26, said in an interview published Thursday by the New Straits Times. He is the youngest son of the 53-year-old pilot, Capt. Zaharie Ahmad Shah.
Investigators have so far been unable to establish why the passenger jet flew far off course on the night it vanished from radar screens almost three weeks ago.
Malaysian authorities say the jetliner and the 239 people it was carrying ended up in the southern Indian Ocean, where a multinational search is trying to locate traces of the plane.
The search efforts were severely hampered by bad weather Thursday, while Thai authorities reported detecting hundreds more objects that could be related to the plane in satellite images.
'I understand him'
The pilot and first officer of the plane have come under particular scrutiny, with a range of speculative theories proffered for why one or both of them might have diverted it from its scheduled flight path to Beijing.
Some of the wilder speculation suggested Zaharie might have hijacked the plane as a political act.
"We may not be as close as he travels so much. But I understand him," Ahmad said of his father in the interview, which was conducted Tuesday.
Ahmad is the first member of the Zaharie's close family to speak publicly to the news media about the plane's disappearance.
No 'smoking gun'
Comments from government officials on the investigation so far support the young man's view.
A senior Malaysian government official on Wednesday told CNN law enforcement analyst Tom Fuentes that authorities have found nothing negative in 19 days of investigating the two pilots that leads them to any motive, be it political, suicidal or extremist.
And an ongoing FBI review of the two pilots' hard drives, including Zaharie's flight simulator, has not turned up a "smoking gun," a U.S. official with knowledge of the investigation told CNN.
"They have accessed the data," the official said. "There is nothing that's jumping out and grabbing us right now."
Officials have so far not reported anything suspicious in their investigations into the 10 other crew members and 227 passengers on board the plane.
American investigators continue to be baffled by the plane's disappearance, with one U.S. official saying, "I don't think there is a prevailing theory. There are counterarguments to every theory right now."
Air search halted
With little sign of progress in the investigation on land, search efforts at sea were hampered Thursday by another bout of bad weather.
The conditions brought an early end to the day's aerial search for the plane in the southern Indian Ocean, but five ships in the area are trying to keep up the hunt for debris despite the difficult conditions.
All the planes that had flown out to the search zone are returning to Perth, the western Australian city where they set out from, the Australian Maritime Safety Authority said. It initially reported that the ships were leaving the search area, too, but later said they would stay.
The search teams that have been out over the remote area of ocean Thursday have been "beaten up," said Lt. Comm. Adam Schantz of the U.S. Navy.
The visibility is almost zero, with clouds reaching down to the surface of the water, as well as severe turbulence and icing, he said.
"It's very cold," said Capt. Allison Norris, who is in charge of the HMAS Success, the Australian navy ship in the search area. "We rotate the lookouts through every hour and make sure that they are appropriately dressed to combat the very cold conditions down here."
Early Thursday afternoon, more than 60% of the search area was experiencing a mixture of low visibility, strong thunderstorms and powerful winds, said CNN International Meteorologist Pedram Javaheri.
Hopes of resuming
Flight crews hope to be back in the air Friday if the weather clears, Schantz said. But the Australian maritime agency said it expects conditions to remain bad for another 24 hours.
This is the second time this week that operations have been hampered by harsh conditions in the isolated patch of ocean roughly 1,500 miles southwest of Perth. No search missions took place on Tuesday because of stormy weather.
The delay is likely to prolong an already protracted hunt for the missing Boeing 777, which disappeared March 8 over Southeast Asia with 239 people on board.
Citing an analysis of satellite data, Malaysian authorities say the plane ended its errant journey in the southern Indian Ocean. But they still haven't been able to establish why it lost contact with air traffic control and flew so far off course.
The suspension of the aerial search dims hopes that the teams might soon be able to pinpoint objects spotted in satellite images of the ocean captured over the past two weeks.
On Wednesday, Malaysia said it had received satellite images showing 122 potential objects floating in the ocean, not far from other satellite sightings that could be related to the missing passenger jet.
Adding to the list, a Thai satellite spotted 300 "pieces of floating objects potentially linked" to the missing plane in broadly the same region of the southern Indian Ocean, a Thai official said Thursday.
The Thai satellite captured the images on Monday, but it took several days to process them and pass them on to the Malaysian government, said Kampanart Deeudomchan, an official at Thailand's Geo-Informatics and Space Technology Development Agency.
Analysts have said the detection of possible objects is an encouraging sign, but so far nothing conclusively linked to the plane has been found.
"The type of wreckage or object that we're looking for is so close to the water line that now radars would not be able to pick it up," Norris of the HMAS Success told CNN's Anderson Cooper. "So we are very reliant on lookouts who use binoculars and night vision glasses to scan the horizon and scan the area around the ship while we conduct our search pattern."
The forecast from Friday morning through Saturday shows much improved conditions in the search zone, CNN's Javaheri said.
"Scattered clouds should be expected," he said. "But the winds and seas will both calm considerably, giving a rare a stretch of generally favorable conditions for this region during this time of year."
Malaysian Remote Sensing Agency (MRSA) received new satellite images from France that were taken on March 23.
The images showed 122 potential objects in one area of the ocean. Some of the objects were as much as 23 meters in length.
Some appeared bright, possibly indicating solid material. They were located about 2,500 kilometers from Perth.
"This is another new lead that will help direct the search operation," said Acting Minister of Transportation Hishammuddin Bin Hussein on Wednesday.
Officials say they can tell you how Flight 370 ended. It crashed into the Indian Ocean, they'll say, citing complicated math as proof.
They can tell you when it probably happened - on March 8, sometime between 8:11 and 9:15 a.m. (7:11 to 8:15 p.m. ET March 7), handing you a sheet with extraordinarily technical details about satellite communications technology.
What they still can't tell you is why, or precisely where, or show you a piece of the wreckage.
See story as it updates on CNN.com.
The crew of a Chinese plane searching for the missing Malaysia Airlines Flight 370 spotted "suspicious objects" in the southern Indian Ocean on Monday, the latest lead in a long and often frustrating investigation.
But a high-tech U.S. search aircraft that followed up on the sighting couldn't find them again, Australian authorities said.
A reporter on board the Chinese plane for China's official news agency Xinhua said the search team saw "two relatively big floating objects with many white smaller ones scattered within a radius of several kilometers," the agency reported.
The Australian Maritime Safety Authority said on Twitter that a U.S. Navy P8 Poseidon aircraft that was tasked to investigate the objects was unable to relocate them.
The IL-76 plane that reported the objects is one of two Chinese military aircraft helping scour a remote area of the southern Indian Ocean on Monday for traces of the passenger jet, which disappeared over Southeast Asia on March 8 with 239 people on board.
With the search in its third week, authorities have so far been unable to establish where exactly the plane is or why it flew off course from its planned journey from Kuala Lumpur to Beijing.
China has a particularly large stake in the search: its citizens made up about two thirds of the 227 passengers on the missing Boeing 777. Beijing has repeatedly called on Malaysian authorities, which are in charge of the overall search, to step up efforts to locate the plane.
A Chinese icebreaker in the region, the Xuelong, has changed course and is headed toward the area where the objects were seen by the Chinese plane, Xinhua said.
Satellites focus search
Recent information from satellites identifying objects in the water that could be related to the plane has focused the search efforts on an area roughly 1,500 miles southwest of the Australian city of Perth.
Eight other aircraft - from Australia, the United States and Japan - are also tasked with combing the search area over the course of Monday.
The two Chinese aircraft are now heading back to base, Xinhua reported. The crew that spotted the objects has asked Australia authorities to send other planes to the area of interest, it said.
The aerial searches have been trained on the isolated part of ocean since last week, when Australia first announced that satellite imagery had detected possible objects that could be connected to the search.
Since then, China and France have said they also have satellite information pointing to floating debris in a similar area. The Chinese information came from images, and the French data came from satellite radar.
But Australian officials have repeatedly warned that the objects detected in satellite images may not turn out to be from the missing plane - they could be containers that have fallen off cargo ships, for example.
The investigation into the passenger jet's disappearance has already produced a wealth of false leads and speculative theories. Previously, when the hunt was focused on the South China Sea near where the plane dropped off civilian radar, a number of sightings of debris proved to be unrelated to the search.
Plane said to have flown low
The sighting of the objects of interest by the Chinese plane came after a weekend during which other nuggets of information emerged about the movements of the errant jetliner on the night it vanished.
Military radar tracking shows that after making a sharp turn over the South China Sea, the plane changed altitude as it headed toward the Strait of Malacca, an official close to the investigation into the missing flight told CNN.
The plane flew as low as 12,000 feet at some point before it disappeared from radar, according to the official. It had reportedly been flying at a cruising altitude of 35,000 feet when contact was lost with air traffic control.
The sharp turn seemed to be intentional, the official said, because executing it would have taken the Boeing 777 two minutes - a time period during which the pilot or co-pilot could have sent an emergency signal if there had been a fire or other emergency onboard.
Authorities say the plane didn't send any emergency signals, though some analysts say it's still unclear whether the pilots tried but weren't able to communicate because of a catastrophic failure of the aircraft's systems.
The official, who is not authorized to speak to the media, told CNN that the area the plane flew in after the turn is a heavily trafficked air corridor and that flying at 12,000 feet would have kept the jet well out of the way of that traffic.
Malaysia disputes reprogramming
Also over the weekend, Malaysian authorities said the last transmission from the missing aircraft's reporting system showed it heading to Beijing - a revelation that appears to undercut the theory that someone reprogrammed the plane's flight path before the co-pilot signed off with air-traffic controllers for the last time.
That reduces, but doesn't rule out, suspicions about foul play in the cockpit.
The new details give more insight about what happened on the plane, but don't explain why the plane went missing or where it could be.
Analysts are divided about what the latest information could mean. Some argue it's a sign that mechanical failure sent the plane suddenly off course. Others say there are still too many unknowns to eliminate any possibilities.
CNN aviation analyst Miles O'Brien called the fresh details about the flight a "game changer."
"Now we have no evidence the crew did anything wrong," he said. "And in fact, now, we should be operating with the primary assumption being that something bad happened to that plane shortly after they said good night."
If a crisis on board caused the plane to lose pressure, he said, pilots could have chosen to deliberately fly lower to save passengers onboard.
"You want to get down to 10,000 feet, because that is when you don't have to worry about pressurization. You have enough air in the atmosphere naturally to keep everybody alive," he said. "So part of the procedure for a rapid decompression ... it's called a high dive, and you go as quickly as you can down that to that altitude."
Flight makes emergency landing
Adding to the negative publicity that has blighted Malaysia Airlines since news of Flight 370's disappearance, one of the carrier's passenger jets made an emergency landing in Hong Kong on Monday.
The plane, scheduled to fly from Kuala Lumpur to Incheon, South Korea, was diverted to Hong Kong after its main electrical generator stopped working. Electrical power continued to be supplied by the plane's auxiliary power unit, Malaysia Airlines said
The Airbus A330-300 landed safely at Hong Kong airport around 3 a.m., and the 271 passengers on board have been transferred onto flights with other airlines.