IT’S BEEN nearly a week since Malaysia Airlines Flight 370 disappeared over — well, no one is quite sure where. Malaysian officials over the past several days expanded their search area to a mind-boggling 27,000 square miles, on both air and land, spanning both sides of the Malay Peninsula. Even with an international fleet of more than 42 ships and 39 aircraft on the scene, the case of this missing plane “is rapidly becoming one of the great mysteries of all time,” David Gallo, an experienced hunter of plane wreckage with the Woods Hole Oceanographic Institution, told us.

This was an avoidable mystery. There are eminently feasible ways to keep track of commercial aircraft, and it’s inexcusable that they are not being used. In fact, they aren’t operating even in the United States. This country’s air traffic control system still relies largely on decades-old radar networks, which have a variety of limitations. The Malaysia Airlines case shows one problem: It’s hard to track aircraft in remote areas, land or sea. A satellite-based tracking system U.S. authorities are installing will help, but it won’t be finished until at least 2020. The United States should at least stick to its timeline.

International aviation authorities, meanwhile, should insist on the deployment of aircraft technology that transmits information in an emergency. That could require new beacons to cover remote areas of land and sea and satellite broadcasting technology on planes. This is reasonable: There’s no excuse for lost iPhones to be more findable than downed planes. There would be a cost to the upgrade. But there is a huge cost, financially and psychically, in launching an armada on a highly speculative hunt when a jetliner is suspected of crashing into an ocean.

This isn’t a new lesson. In a feat of undersea exploration, Mr. Gallo led a team that recovered the black boxes from a downed Air France jet in 2011 — two years after the plane had crashed into the Atlantic Ocean on its way from Brazil to France. Now, three years later, the world is again at a loss. There’s simply no reason, given the available technology, that it should be just as possible for an airliner to vanish today over the Pacific as it was for Amelia Earhart nearly 80 years ago.