Volunteers from Taiwan's Buddhist association offer prayers for the Chinese passengers aboard the missing Malaysia Airlines flight MH370, at a hotel in Beijing, China Tuesday, April 1, 2014. Although it has been slow, difficult and frustrating so far, the search for the missing Malaysia Airlines jet is nowhere near the point of being scaled back, Australia's Prime Minister Tony Abbott said. The three-week hunt for Flight 370 has turned up no sign of the Boeing 777, which vanished March 8 with 239 people bound for Beijing from Kuala Lumpur. (AP Photo/Andy Wong)
Malaysian PM: We will not give up
01:41 - Source: CNN

Story highlights

NEW: The search is "the most difficult in human history," Australia's Abbott says

"We will not rest until answers are indeed found," Malaysian PM says

Australian ambassador: Focus moves due to searchers "eliminating areas"

Official: All 227 passengers have been cleared of hijacking, psych issues

Kuala Lumpur, Malaysia CNN  — 

Many have pointed to lessons learned – and heeded – from the disappearance of Malaysia Airlines Flight 370.

Should there be tighter rules about who’s in the cockpit? That’s happened. Should the Malaysian military have acted more quickly after the airliner went missing nearly four weeks ago? They’ve launched an investigation. Are there better ways to track commercial aircraft – especially when, as in this case, its transponder is turned off? An international aviation organization says it will consider “all of the options.”

But as much as things might change because of this mystery, it doesn’t change the fact that – for yet another day – there are 239 families still grieving, still waiting, still venting over authorities’ inability to answer what happened to the Boeing 777.

“We want to provide comfort to the families and we will not rest until answers are indeed found,” Malaysian Prime Minister Najib Razak said Thursday during a visit to a military base near the Australian city of Perth, which has become the hub for search operations.

Mystery of Malaysia Airlines Flight 370 surfaces pain of 1977 tragedy

Yes, authorities have said communications mysteriously, and seemingly purposefully, cut off shortly into the Beijing-bound flight. Yes, satellite data suggests the aircraft turned back over Malaysia before terminating somewhere in the vast southern Indian Ocean.

Yet there have been no solid leads about why any of this happened or where the plane ended up. In fact, officials don’t seem to know all that much more on Day 27 after it disappeared sometime after leaving Kuala Lumpur than they did on Day 1.

Australian Prime Minister Tony Abbott on Thursday described the search for the plane as “the most difficult in human history” and warned there was no guarantee it would be found.

“We cannot be certain of ultimate success in the search for MH370,” he said at a news briefing in Perth, standing alongside Najib. “But we can be certain that we will spare no effort – that we will not rest – until we have done everything we humanly can.”

All 227 passengers have been cleared of any role in hijacking or sabotage or having psychological or personal issues that might have played a role in the plane’s disappearance, the inspector general of Malaysian police, Khalid Abu Bakar, told reporters Wednesday.

Police said Wednesday a review of a flight simulator found in a pilot’s house proved inconclusive. And senior Malaysian government officials told CNN last week that authorities have found nothing about either of the pilots to suggest a motive. There have been no such public comments about the other 10 crew members, however.

“We don’t have enough evidence to take (hijacking, sabotage or many other possibilities) off the table,” Michael Kay, a former British pilot and military officer, told CNN. “What we need to do is keep an open mind, look at the facts, and keep building the jigsaw puzzle. Because that’s all we have at the moment.”

On Thursday, up to eight aircraft will set out looking for telltale debris across an 91,500 square-mile (237,000 square-kilometer) zone, the Australian Maritime Safety Authority says. Up to nine ships will search, including one British submarine racing against time to hear the signature pinging from Flight 370’s flight data recorder.

There could be a breakthrough imminently; a seat cushion, a soda can, a life jacket could be spotted and scooped up, leading to the rest of the plane and, ultimately, to explain what happened.