Afternoon update: A U.S. official not authorized to speak on the record for attribution says the plane operated for “4 or 5 hours” after radar contact was lost early Saturday morning. This information comes from a new technology that has never been used before in an investigation like this. The plane had an ACARS system in which information could be bounced off a satellite back to land, but that system had been turned off. Nonetheless — and here is where it gets technically tricky — there was still a “handshake” between the satellite and the plane’s ACARS system. No data was transmitted either way, but the “handshake” signaled that the plane was still operational. The handshake didn’t reveal location, but did reveal the degree to which the satellite would need to adjust its antenna to receive or transmit data to the plane. This, in effect, means somewhere along a vast arc is where the plane could be during that handshake. After “4 or 5 hours” the handshakes stopped. [So the plane should be somewhere within 1 hour of operational flying from the edge of a circle that could be thousands of miles in diameter — it’s all geometry, just in time for Pi day.] (By the way, the plane did not “ping” the satellite, as has been sometimes reported. There are pingers on a plane to signal location in an accident, but this is different. Moreover, it’s the satellite that initiates the handshake.) Remember: This is new technology being interpreted in an unusual way in a high-profile accident investigation; don’t be surprised if there’s a change in interpretation at some point.

This morning’s blog post:

Where is that plane? We’re all quite obsessed with this story, which, as I wrote Wednesday, is the mystery of the year. For the families it must be excruciating not to know what happened. For the searchers it must be confusing — they’ve switched seas now, and are expanding the search into the Indian Ocean, and if you look at the big map on the front of today’s Post you’ll see that roughly a large portion of the planet was theoretically reachable by a plane with that much fuel aboard. Australia. Japan. Papua New Guinea. Siberia. Saudi Arabia. And a whole lot of ocean.

All we have to go on are some ambiguous satellite pings and radar blips.

The story took a big turn Thursday when officials said the plane sent those pings to a satellite for an additional 4 hours after it disappeared [Update: I should note that the Wall Street Journal broke this story and has updated/modified it; here’s the latest version that I’ve seen]. I’d caution everyone that this is a single data-point and we may yet learn an alternative explanation (I’m still trying to understand, technically, how the plane communicates with the satellite; post a comment if you know; here’s an AP explainer on it). Those pings don’t tell us about location or altitude, either. The blips, meanwhile, are a few radar blips picked up by the Malaysian military that suggest a plane — maybe this plane — was headed west, in the general direction of the Andaman Islands, early Saturday morning. But again, this is fuzzy stuff. There are also reports that instruments were switched off  or became disabled sequentially on board the plane, which could indicate a malevolent intent. All this together makes it plausible that the plane was hijacked or intentionally diverted to some other location — and you can’t rule out the possibility, remote though it is, that the plane landed somewhere intact. [Update: The Journal story also included an anonymously sourced but sensational detail: “At one briefing, according to one of the people, officials were told that investigators are actively pursuing the notion that the plane was diverted ‘with the intention of using it later for another purpose’." Meanwhile CNN floats the theory that the plane landed in the Andaman Islands, which a newspaper editor there says is preposterous — you couldn’t do it without everyone noticing.]

But it’s all pretty thin evidence right now and Malaysia Airlines Flight 370 may simply have suffered some kind of electrical or mechanical failure that led to a crash.The lack of a debris field is puzzling, but this happened in the middle of the night in a remote location.

At SkyTruth, John Amos has an interesting post that looks over satellite data for signs of fires not caused by the flaring of gas at offshore oil rigs. What’s interesting in these images is how much dense jungle is in the path of the plane. Could a plane have crashed in an uninhabited portion of, say, Cambodia, and not been discovered?

Update: Reuters reports that the plane may have been following a well-traveled path to the Middle East and Europe:

Analysis of the Malaysia data suggests the plane, with 239 people on board, diverted from its intended northeast route from Kuala Lumpur to Beijing and flew west instead, using airline flight corridors normally employed for routes to the Middle East and Europe, said sources familiar with investigations into the Boeing 777’s disappearance…

The military track suggests it then turned sharply westwards, heading towards a waypoint called “Vampi”, northeast of Indonesia’s Aceh province and a navigational point used for planes following route N571 to the Middle East.

From there, the plot indicates the plane flew towards a waypoint called “Gival”, south of the Thai island of Phuket, and was last plotted heading northwest towards another waypoint called “Igrex”, on route P628 that would take it over the Andaman Islands and which carriers use to fly towards Europe.

[more to come…]