"Aviation investigators and national security officials believe the plane flew for a total of five hours, based on data automatically downloaded and sent to the ground from the Boeing Co. 777's engines as part of a routine maintenance and monitoring program."
Well, if the engines were transmitting, can't someone figure out the direction of the plane?
I guess it depends on the data transferred. For an engine you probably have data like altitude, revolutions/second, fuel intake, pressure, etc. To get a status on the engines you probably don't NEED long/lat data. So it might not be in the transmitted bursts.
Maybe there is a way of interpreting the data that tells you when/if the plane turned. e.g. "the chamber pressure in engine 2 is 5% higher than engine 1 ==> the plane was turning left at a rate of 15° per minute". Something crazy like that
I wonder if the necessary transmission origin data wasn't recorded? I bet the fbi is right now going through boeing's network trying to figure that out though. Is it bounced through satellites? You'd think a XXX million dollar plane would have a gps beacon or something though, just like atm machines.
It would be a miracle if it where hijacked and there's even a chance those people are alive.
They have a GPS beacon. The ADS-B system is exactly that. It just stopped transmitting. Apparently it can be manually turned off from the cockpit. Or it malfunctioned.
> Well, if the engines were transmitting, can't someone figure out the direction of the plane?
Unfortunatley not; the flight-data transmitting systems ( ACARS and ADS-B ) that do include position data appear to have been turned-off or disabled deliberately.
The engine telemetry feed is part of Rolls-Royce's 'Power by the Hour' system, which aims to identify faults or under-performance in the engines whilst still in-flight so that an engineer can tune and correct when the aircraft arrives. It doesn't care where the aircraft is.
Though... it might include environmental data such as inlet pressure and temperature, which could help to determine altitude.
If they received the data that means the engines managed to communicate somehow. So that tells you the length of time the transmission unit was powered up. Also, using differential signal strength between successive communications one can generate an approximate trajectory (x km from satellite at y time) etc etc. This would surely narrow down the possible locations.
So why don't planes do that that? You need 24 bits for 3 meter GPS accuracy (times 2). Add some extra for altitude and airplane ID (or does a unique ID come built in?) So maybe 80 bits in total.
This would be nothing for an airplane - $0.40 per hour? Why don't they do this already?
Actually rules made by the FAA do pretty much affect every nation. Many nations do not have their own version of the FAA and just rely on the US.
But it's even easier than that: Just make all US owned airlines require it, and any flight landing in the US. Phase it in, etc, to give time to upgrade, but it's certainly possible.
I believe that Rolls-Royce doesn't sell it's engines; it leases them instead. So engine telemetry data from many airlines is transmitted to the engine's owner, which happens to be a central organisation.
(Of course, it is a business, rather than branch of a government, and not the only manufacturer of jet engines).
Care to link to it? I didn't find anything by "Stross".
My numbers were $0.40 per hour, plus a few hundred for the equipment (it's available off the shelf, don't need anything custom). Don't know how much installation would be, but certainly not millions.
If the system sends signals EXACTLY every 30 minutes, then a very careful reconstruction of signal running times (combined of course with the positions of the recieving antennae and the EXACT times the signals were recieved) can reveal information about the heading and position.
That's a good point, if the timestamps have the necessary precision and their clock drift info hasn't been lost by a resync since then. I'd guess that since exact time isn't crucial to the purpose of these messages, though, that they probably don't have very high precision timestamps. :-(
Well, if the engines were transmitting, can't someone figure out the direction of the plane?
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