MH370: Search for plane suspended due to bad weather

Meanwhile, a U.S.-based law firm filed court documents that often precede a lawsuit on behalf of a relative of an Indonesian-born passenger. The filing in Chicago asked a judge to order Malaysia Airlines and Chicago-based Boeing Co. to turn over documents related to the possibility that “negligence” caused the Boeing 777 to crash, including any documentation about the chances of “fatal depressurization” in the cockpit.

Though officials believe they know roughly where the plane is, they don't know why it disappeared shortly after takeoff. Investigators have ruled out nothing including mechanical or electrical failure, hijacking, sabotage, terrorism or issues related to the mental health of the pilots or someone else on board.

And finding the wreckage and the plane's flight data and cockpit voice recorders is a major challenge. It took two years to find the black box from Air France Flight 447, which went down in the Atlantic Ocean on a flight from Rio de Janeiro to Paris in 2009, and searchers knew within days where that crash site was.

The batteries on the recorders' “pingers” are designed to last 30 days. After that, the pings begin to fade in the same way that a flashlight with failing batteries begins to dim, said Chuck Schofield of Dukane Seacom Inc., a company that has provided Malaysia Airlines with pingers in the past. Schofield said the fading pings might last five days before the battery dies.

If a general area is pinpointed for the wreckage, experts say depths will area range from 3,000 to 4,500 metres (10,000 to 15,000 feet).