The mystery deepened this week surrounding the Malaysia Airlines flight that disappeared without a distress call last week, one hour after taking off from Kuala Lumpur. Flight 370 last made radar contact with air traffic controllers from 35,000 feet over the Gulf of Thailand. As The Week went to press, a Chinese defense agency said that Chinese satellite images taken a day later might show three large pieces of floating debris near its last known location, which could allow investigators to narrow the 27,000-square--nautical-mile search area. But no wreckage had been found four days after the plane vanished, intensifying the grief for families of the 239 people aboard.

Malaysian authorities said they were considering many possible theories, including mechanical failure, pilot error, terrorism, and pilot suicide. Questions arose about whether the Boeing 777 had been inspected for fuselage cracks, a model-specific problem that the U.S. Federal Aviation Administration warned last year “could lead to rapid decompression and loss of structural integrity.”

The sudden disappearance of an aircraft is not unprecedented, said Jordan Golson in Commercial airliners are not in constant contact with air traffic control, and radio communications generally occur only at fixed “reporting points.” Pilots are trained to “aviate first” and communicate last, so a catastrophic event may have precluded a distress call. And while the cause remains unknown, most experts believe the incident occurred at high altitude, scattering debris over a vast area. Wreckage from the 2009 Atlantic Ocean crash of Air France Flight 447 wasn’t found for five days, and the plane’s “black box” data recorder wasn’t recovered for two years.

So “why isn’t black box data transmitted in real time?” asked The New York Times in an editorial. The typically bright orange devices store vital data such as telemetry and cockpit communications. The technology exists for that data to be streamed as it is collected, rather than stored “in a physical object that stays onboard.” To date, the rarity of in-flight disasters and the cost of new equipment have kept most carriers from upgrading. “But there is a cost of doing nothing,” such as trying to find a tiny box in a vast ocean.