Chinese businessman Li Hua suffered a stroke, has considered suicide, and his wife has been hospitalised with heart trouble, all since their daughter went missing on flight MH370.

A. Amirtham, a retired Malaysian clinic worker, suffers fainting spells and a lack of sleep and appetite over the disappearance of her only son Puspanathan.

Li Jiuying is tormented by the loss of her big brother Li Guohai and the burden of lying to their elderly mother that he was not on the flight. The mother believes he is tied up with a business dispute.

One year after the Malaysia Airlines jet vanished, next of kin are trapped inside what one describes as a "black hole" of emotional and often physical suffering.

Li Hua, 58, who only recently recovered the full use of his left arm following last year's stroke, used to be a fitness buff.

"Now I just feel sick," he said, chain-smoking.

"I have thought of suicide but... why? I need to stay alive for my wife and fight for the truth."

- 'Nothing can be the same' -

But the truth remains painfully elusive for families as the tragedy's March 8 anniversary nears.

In one of aviation's most baffling mysteries, the Boeing 777 with 239 people aboard inexplicably detoured from its Kuala Lumpur-Beijing route, heading west and south into the Indian Ocean and history.

A year-long search in that ocean's remote southern reaches -- now focussed on high-tech sonar scanning of the seabed -- has found nothing.

The vanishing act is not without some concrete outcomes.

World aviation authorities last month mandated minute-by-minute tracking of aircraft in distress, beginning globally next year, to prevent a recurrence.

This week, Australia said it also was conducting trials, with Malaysia and Indonesia, of a system that increases the frequency with which planes are tracked over remote oceans.

But all of that is little comfort now for MH370 families.

They endured an emotional trial of false leads and dashed hopes during Malaysia's chaotic initial response, which included its air force's failure to act despite tracking the plane shortly after it diverted.

Many are now incensed over the January 29 declaration that all on board were presumed dead and families should seek compensation.

Next of kin fear the move means the Malaysian government and airline are poised to declare the matter closed without any resolution.

"There is no closure for us," said Grace Subathirai, a Malaysian attorney whose mother Anne Daisy was on board.

"It has totally changed our lives. Nothing can ever be the same."

- 'Too painful' -

Malaysian authorities have revealed no new information for months, and said in January the disappearance remains a mystery.

The government and airline insist they are being transparent and are committed to the Australia-led search. Both declined interview requests.

For many relatives, grief is compounded by the perceived callous attitude of the Malaysians and suspicions that the full truth is not being told.

Among the hardest hit are families from China, whose nationals comprised two-thirds of the passengers. Many lost their sole offspring under China's one-child policy.

Nearly two dozen Chinese relatives have been in Malaysia since last month to press authorities for answers. They say they have been rebuffed.

Many complain of sleeplessness, appetite loss, panic attacks and more serious ailments like hypertension and heart problems.

Several said they had not returned to their homes since last March 8.

"How can we go back? We would see his things. It is too painful," said Wang Rongxuan, 60, who lost her 37-year-old son Hou Bo.

Angrily rejecting the notion that he is dead, Wang burst into tears, insisting he would return.

- 'A black hole' -

MH370 families are suffering what is called "ambiguous loss", the disappearance of loved ones with no clue to what happened, said Sarah Wayland, a Sydney-based expert on counselling relatives of missing persons.

"People become frozen to the time that person went missing," she said.

"The only way for many to survive is to accept that they may never know. That's incredibly difficult and can take years."

Families are in "a black hole", crushed by their loss, but unable to start grieving and healing until the plane's fate is clear, said K.S. Narendran, a business consultant in Chennai, India, whose wife Chandrika Sharma was on board.

Resulting stress has worsened his diabetes. Neck and arm maladies also have emerged.

He copes by blogging frequently on the latest speculation, but is tormented by the lack of closure since the disaster.

"Families have reckoned with the fact that a loved one is gone," he said.

"But to put it behind us and just move on? We don't quite know how to take that next step."

Timeline: The fruitless year-long hunt for MH370
Kuala Lumpur (AFP) March 4, 2015 - One of the most baffling aviation mysteries ever seems no closer to being solved as the first anniversary of Malaysia Airlines Flight MH370's disappearance approaches on March 8.

Following is a timeline of major developments in the disappearance of the Boeing 777 and its 239 passengers and crew:

SATURDAY MARCH 8

-- Flight 370 departs Kuala Lumpur at 12:41 am, bound for Beijing. It vanishes from Malaysian civilian radar at 1:30 am, just before passing to Vietnamese air traffic control. It appears on military radar until 2:15 am, but Malaysia's air force takes no action.

-- Vietnam launches a search operation that expands into a multinational hunt in the South China Sea.

-- Two passengers who were travelling on stolen EU passports spark speculation of a terrorist attack, but are revealed to be merely suspected Iranian illegal immigrants. Malaysian police later say background checks of all on board produced no red flags.

SUNDAY MARCH 9

-- Malaysia's air force chief says the plane may have turned back towards Kuala Lumpur for no apparent reason, citing radar data. In the coming days, the search area expands to the west of the Malaysian peninsula and the air force confirms the blip on its radar was indeed MH370.

FRIDAY MARCH 14

-- The hunt spreads far south to the Indian Ocean after the White House cites "new information" that the jet may have flown on after losing contact.

SATURDAY MARCH 15

-- At a dramatic news conference, Malaysian Prime Minister Najib Razak says the plane appears to have been flown deliberately for hours, veering sharply off-route at roughly the same time that its communications system and transponder were manually switched off.

-- Satellite data suggests the jet's last known location was somewhere along one of two huge arcs stretching north into Central Asia and south into the Indian Ocean. The South China Sea search is called off.

SUNDAY MARCH 16

-- With more than two dozen countries now involved in the search, suspicions focus on the pilot and co-pilot, both Malaysians. FBI experts examine the hard drive on a flight simulator in Captain Zaharie Ahmad Shah's home, but find nothing suspicious.

THURSDAY MARCH 20

-- Australia says satellites photographed two large objects in the remote southern Indian Ocean, but the flotsam proves to be another in a series of a false alarms.

MONDAY MARCH 24

-- Najib announces "with deep sadness and regret" that MH370 is presumed to have crashed in the Indian Ocean, citing new analysis of satellite data.

The next day in Beijing, emotional Chinese relatives of passengers scuffle with guards outside the Malaysian embassy, demanding answers.

MONDAY MARCH 31

-- Malaysia releases a transcript of all the pilots' radio communications, but it sheds little light.

FRIDAY APRIL 4

-- A US-supplied "black box" detector begins scanning the suspected crash zone, with the clock ticking on the one-month battery life of their locator beacons.

SATURDAY APRIL 5

-- A Chinese search ship detects an underwater "pulse signal" in the Indian Ocean. More "pings" are detected by other vessels in subsequent days, but they cease before they are pinpointed. Some experts later express doubt they were related to MH370.

MONDAY APRIL 14

-- Halting the search for underwater signals, Australia deploys an American deep-sea drone to scan the seabed for debris near the ping sites. It ultimately finds nothing.

MONDAY APRIL 28

-- Australia announces the search area will be expanded across a huge swathe of ocean. The focus shifts for several months to mapping the uncharted seafloor before searching can resume.

TUESDAY MAY 27

-- After weeks of pressure from families, Malaysia releases raw satellite data used to determine the search zone. Relatives say crucial data was omitted.

MONDAY OCTOBER 6

-- A Malaysia-contracted vessel resumes the sonar search of the seabed for debris. Three specialised Dutch search ships eventually join an effort expected to wrap up in May 2015.

THURSDAY JANUARY 29

-- Malaysia's government declares MH370's passengers and crew "presumed dead", angering next of kin who demand proof.

WEDNESDAY FEBRUARY 4

-- Prompted by the MH370 mystery, a global aviation summit in Montreal backs plans to require real-time tracking of any airliners that encounter distress, starting in 2016.

WEDNESDAY FEBRUARY 25

-- Australian authorities say vessels have completed scanning about 40 percent of a 60,000-square-kilometre (23,166-sq-mile) "priority search area" -- and found nothing.

SUNDAY MARCH 1

-- Australia says it is conducting trials with Malaysia and Indonesia of a system that increases the frequency with which planes are tracked over remote oceans, to avoid an MH370 recurrence.