[Azure]

Good article explaining some of the questions some of us have.

http://www.wired.com/autopia/2014/03/malaysia-air/

It is a misconception that airline pilots are in constant communication with air traffic control, or that planes are constantly watched on radar. Once a plane is more than 100 or 150 miles from shore, radar no longer works. It simply doesn’t have the range. (The specific distance from shore varies with the type of radar, the weather, and other factors.) At that point, civilian aircraft communicate largely by high-frequency radio. The flight crew checks in at fixed “reporting points” along the way, providing the plane’s position, air speed, and altitude. It isn’t uncommon to maintain radio silence between reporting points because cruising at 35,000 feet is typically uneventful. Some aircraft communication systems don’t require pilots call in; flight management computers transmit the info via satellite link.

Although modern flight management systems use GPS for navigation, that only tells the airplane where it is–it does not tell air traffic control where the plane is. It’s a bit like taking your iPhone into the heart of the Mojave desert: Your GPS will tell you where you are, but you can’t use Find My Phone because there’s no cell coverage. Although it would be possible to stream data from an aircraft in real time via satellite, implementing such a system across the industry would cost billions of dollars, Smith said.

Still, it is highly unlikely that Flight 370 went down silently, Joseph said. Many commercial aircraft have an emergency locator beacon that the flight crew can trigger in an instant. It also will activate under certain circumstances, such as impact with water–though it isn’t effective a great depths. And although civil aviation systems don’t have radar or other tracking technology at sea, military and security agencies almost certainly do. It’s possible a government ship, airplane or satellite captured some clues, as was the case when a Soviet fighter jet brought down Korean Air Lines Flight 007 in 1983.

“I would be very surprised if, on somebody’s radar data, this event was not recorded,” Joseph said.