It has been one year since Malaysian Airlines flight 370 (MH 370) vanished. The passage of time has brought no relief to the families of the 239 people who were lost in this inexplicable tragedy. There are, as yet, no answers or explanations for what happened that night.

MH370, en route from Kuala Lumpur to Beijing, took off just after midnight on March 8, 2014 and had transitioned from the Kuala Lumpur air traffic controllers to those in Ho Chi Minh City, Vietnam, when it vanished. While the flight should have continued in a northerly direction toward the Chinese capital, the plane was revealed some days later to have turned west, crossing the Malay Peninsula and continuing out of radar range until it disappeared.

The search for the plane has been marked by confusion. The original search occurred in the South China Sea — where MH370 would have been according to its original flight plan — but after confirming that the plane had changed direction, the search area widened.

Analysis of communications between the plane and a telecommunications satellite revealed that MH370 had flown south and crossed deep into the Indian Ocean.

Since then, the authorities have conducted the largest and most expensive search in aviation history. More than 4.4 million sq. km of territory has been searched in total, at a cost of $93 million. Unfortunately the primary search area is roughly 1,700 km off the western coast of Australia and subject to severe weather. More than 24,000 sq. km, or about 40 percent of the "priority search area" of 60,000 sq. km, has been searched, Despite the use of sophisticated sonar equipment, echo sounders and cameras, nothing — not a single piece of wreckage — has been found. The work is scheduled to continue until May, although adverse weather, such as the cyclones that struck in February, could slow it down.

It is not yet clear what will happen when that priority area search is concluded. One of the most brutal questions is who will foot the bill for the ongoing effort; Australia has reportedly paid about $70 million of the initial cost and Prime Minister Tony Abbott has acknowledged that his country cannot promise that the search will continue "at this intensity forever." The Malaysian government has said it will "continue all reasonable efforts to bring closure to this unfortunate tragedy."

It was jarring, therefore, when the Kuala Lumpur government in January officially declared that MH370 was an accident and that no passengers had survived. Seemingly callous, this was in reality a necessary step according to international protocol if the government was going to commence paying insurance to the victims' families. The decision was especially disconcerting because the announcement was made in the absence of any new evidence or information.

As might be expected, disappearance of the plane has triggered a variety of theories about what transpired that night. One analyst believes that the communications data has been misinterpreted or deliberately "spoofed" and the plane headed north, not south as believed, toward Kazakhstan. Another theory focused on the cargo of lithium-ion batteries that are potentially flammable. Another early line of speculation suggested that the plane had been hijacked or the pilot or copilot deviated from the flight path for some unknown reason. An interim report released by the Malaysian government last weekend concluded that there were "no behavioral signs of social isolation, change in habits or interest, self-neglect, drug or alcohol abuse of the captain, first officer and the cabin crew." An examination of the personal lives of the flight crew as well as films of the flight crew on previous flights revealed nothing that would give rise to any suspicions.

One potentially important piece of information was disclosed in last weekend's report: The battery of the underwater locator beacon on MH370's flight data recorder had expired more than a year before the plane's disappearance.

While a battery could operate past its expiration date, it is not guaranteed to work or to function to its 30-day minimum requirement. Given the amount of time that was lost before the proper crash site was identified, that 30-day window may not matter much, but the families of the victims will forever wonder what might have been.

Similarly, they, along with other airline passengers, will wonder why most planes are not constantly reporting their position to airline authorities, which would allow them to be tracked more accurately. Currently aircraft ping their position every 30 to 40 minutes.

A trial program being used by Malaysia, Australia and Indonesia pings every 15 minutes. Again, such a change might not have mattered: Investigators have no answer as to why the aircraft's transponders were turned off. Given the changes in direction that occurred before the plane vanished, it looks like someone was trying to hide.

Officials remain "cautiously optimistic" that MH370 will be found. They must. The best way to ensure this type of accident never happens again is to discover what happened to MH370. Such patience paid off in the search for Air France flight 447, which took two years to find the black boxes. Closure — personal and professional — is every bit as urgent in this case.