But we also know that there were multiple handshakes made between the satellite and the plane. Officials have concluded from that that the plane had flown for hours after disappearing from radar. So here's the question: What else can we determine from those extra handshakes? If one data point can indicate MH370's distance and angle relative to the satellite, couldn't a string of them — which we apparently have — help plot the aircraft's trajectory? Why aren't we looking more closely at the other data? Why is the last one so important?
We can plausibly guess that this idea has already occurred to someone. Inmarsat says it's shared its information with Malaysian Airlines. But it's not clear why officials haven't said more about this line of reasoning.
According to an industry expert who declined to be identified because he wasn't authorized to speak publicly, the final handshake provides investigators the most up-to-date information they'd need to calculate how much fuel the aircraft had left, how to expand the search area, and so on. That's true, so far as it goes. But the search parameters could be even narrower if we at least knew which direction the plane was headed.
The map above suggests officials have no idea whether the plane turned north or south. The confusion is reinforced somewhat by all the speculation about how MH370 could have avoided radar installations in Afghanistan, China, India and Pakistan.
But the other handshake signals could conceivably offer an important clue. If the other hourly pings produced a pattern that showed the plane's angle changing in relation to the satellite but its distance from it never changed, we might conclude that the aircraft was traveling along the red line rather than perpendicular to it. If, on the other hand, the pings produced a pattern with all the same angle in relation to the satellite but otherwise showed diminishing distances from it, we might conclude that the plane was closing in on the satellite's position.
Unfortunately, it's not clear what the pattern looked like, because officials have only publicly commented on the last ping. And there's still one crucial flaw in looking at the plane's trajectory before it made the final handshake: We still don't know what happened afterward. It could've turned north, or it could've turned south. Or it could've continued on.
Update: Australian officials are now searching a patch of ocean southwest of Perth based on calculations by the U.S. National Transportation Safety Board. The calculations, according to the Sydney Morning Herald, relied on satellite pings provided to Australia by U.S. officials. If true, it suggests that investigators did in fact find the other handshakes useful.