This begs the question: why on earth is it even possible to turn off a transponder mid-flight on a commercial plane carrying hundreds of human beings? I also don't understand why, if we can send bursts of engine data every 30 minutes from the middle of the ocean, we can't send a GPS location every couple of minutes. Maybe even throw some GPS data in with the engine data - at least we would know where it was within a 30 minute window. We're talking about a few extra bytes.
Maybe I'm extremely naive, but it seems to me that you shouldn't be able to turn the transponder off in a commercial passenger flight, and that international medium/long-haul flights that are likely to be in areas with reduced transponder coverage should be required to have some sort of Iridium beacon (which also cannot be turned off).
Even sending the coordinates every 15 minutes would greatly reduce the area to search, and preventing disabling the transponder safeguards against nefarious or suicidal crew/passengers/terrorists.
If I didn't know better (MH370), as a laymen I would have assumed all major flights would be sending their GPS locations constantly via satellite already, for a slew of reasons (one of them being it's 2016).
We could stream this information via satellite uplink. Instead Radar and transponders is used to keep a close enough location to make recovery generally strait forward.
It’s really turning off the transponder while over the middle of the ocean that’s the issue for MH370.
I'm having a hard time telling from the article - are the ships' GPSes actually reporting that they're at the airport? Or is the disconnect happening somewhere between GPS and AIS (eg they're intentionally transmitting bad location data- it's been common-ish in the past for ships to do this when doing something naughty (blockade running or illegal fishing) and given what's going on in the region I can see the value of keeping your location obscure for safety
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?
I think he may mean that airliners transmit their GPS coordinates (which I've heard an ordinary citizen can pick up cheaply) but can't receive commands that way.
This isn’t for pilots to know where they are, it’s for air traffic control to know where planes are.
If GPS were to become the sole way to do the latter, every airplane would effectively get an invisibility cloak that those who want to do evil can activate (and even worse. Switching off the on-board transmitter is less scary than spoofing signals)
Because of that, I would expect they keep using some way to detect planes that don’t tell them where they are, or radios broadcasting “plane P is at X,Y,Z” without a plane being there.
I deploy satellite-comm GPS tracking equipment on machinery in the ski industry.
What I don't get is why airlines insist on bundling emergency telematics along with position tracking. It massively complicates what otherwise is a pretty simple problem. It feels like that description of the Bradley Fighting Vehicle out of the Pentagon Wars movie.
With a box the size of a Big Mac, at <$1k per unit and about $100/month in data costs, you could deploy an off-the-shelf industrial grade tracking unit that would transmit location/speed/altitude every 10 seconds whenever the unit is powered. All it would need would be a power supply. This would neatly solve the "where the heck is the plane" problem, globally, for a fairly trivial cost.
I realize that finding a spot on the plane to mount it, verifying aerodynamics, figuring out how to wire it in, testing, doing the work across a fleet and managing all that data all end up costing a lot more than the equipment, but given the costs being quoted for some solutions in the articles that have been coming up, it really seems like the airlines could have a big PR win by paying for it with petty cash out of their marketing/advertising budget.
And they are free to do so because the GPS units pose no risk to the aircraft, just as I use my iPad or smartphone on a plane.
Once you start talking about tracking systems that are tied into the plane's avionics in order to deliver information about the aircraft itself, that's another story.
Okay so let me get this straight: you're telling me that passenger airplanes currently fly by dead reckoning or stellar navigation or ground-based triangulation or something else? When a pilot doesn't know where he is, he doesn't have any kind of certified GPS-based system handy to tell him?
And moreover, even beyond GPS: how the hell can a plane's navigation system be capable of (and certified for!) landing the monster under autopilot, and yet not be able to tell the pilot its own location within the accuracy of a few feet reliably? I literally do not understand how what you're saying makes any sense.
Thanks for that description. Amazing that Airbus hadn't addressed this already. I've read that the initial problem that confused the pilots was the lack of air speed (and maybe altitude) data, due to frozen pitons. So I still wonder why the planes couldn't use GPS for that, at least as backup.
The passenger cabin is already a pretty good approximation of a Faraday cage. As far as aircraft GPS go, their antenna is on the outside of the fuselage, top, (because it wouldn't receive a signal on the inside) and connected to the GPS receiver with a shielded coaxial cable. So, I'm not buying any of this nonsense about cell phones and readers and video games mucking up the GPS.
I’d like to understand how we keep losing planes. Satellite internet+GPS could enable semi-realtime location tracking for all planes. Instead we get cases like MH370, where we are completely clueless where a plane went.
So does the Air France crash. Speaking of which -- could GPS be used as yet another backup device for airspeed? It might have high latency, but it would be better than nothing.
reply