
How Can an Aircraft Disappear Over the Ocean? - wglb
http://www.technologyreview.com/news/533871/could-passenger-planes-be-tracked-more-closely/
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davidlumley
Why is there no information about the Inmarsat and Iridium networks that a lot
of aircraft already use?

ADS-B is fantastic for fast, accurate position data, and apart from the
hardware is essentially 'free' for an aircraft to make use of.

Satellite transceivers are also relatively cheap (a few thousand dollars), but
the main expense is in sending data to and from the transceiver. This cost can
be alleviated by having the transceiver programmed to send a position report
from every 30 seconds to every few minutes.

It's also possible to switch between ADS-B, and satellite networks when in
range of ADS-B ground stations to make things more efficient.

Satellite tracking fairly ubiquitous in Australia, New Zealand, the UK, and
the US – there's even some consumer level products such as SpiderTracks [
[http://www.spidertracks.com/collections/hardware/products/ha...](http://www.spidertracks.com/collections/hardware/products/hardware-
spider-s5) ] which provide similar SBD modems (Iridium network) to those used
in commercial aviation.

I'm guessing it's just not a requirement for aircraft operating in that
airspace to use satellite tracking, as there was even less data about Malaysia
Airlines flight MH 370.

Source: Worked at a company that provided both hardware and a web based
application to commercial airlines to track their fleets.

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optimusclimb
That article used the word "expensive" many times, but I really have no idea
what that translates to. What could be more expensive than losing a few
hundred lives and an aircraft?

Does the tech used in PLBs such as the spot messenger not work over the ocean?

~~~
dzhiurgis
They do. That's what they are intended for.

They even make lifejackets with then nowadays.

Pathetic.

Edit: did not see parent mentioned SPOT messenger. These have reduced
coverage, as they are not emergency beacons.

~~~
mikeash
Note that SPOT coverage is _not_ worldwide, and it won't work in some parts of
the world, both ocean and land:

[http://www.findmespot.com/en/index.php?cid=108](http://www.findmespot.com/en/index.php?cid=108)

It is quite good though, and would have worked for the mysterious Malaysia
disappearance as well as the recent one. I'm sure other systems exist with
better coverage and higher prices.

~~~
dzhiurgis
Is that same as EPIRB run on Cospas-Sarsat programme?

The coverage looks quite similar
[http://www.marsat.ru/coverage%20maps/GAN_coverage_I3.gif](http://www.marsat.ru/coverage%20maps/GAN_coverage_I3.gif)

~~~
mikeash
It seems that the underlying service is run by Globalstar:

[http://www.globalstar.com/en/index.php?cid=106&sidenav=232](http://www.globalstar.com/en/index.php?cid=106&sidenav=232)

It looks like Cospas-Sarsat is for emergency use only, while SPOT is used both
for emergency location and for routine tracking.

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aosmith
For anyone interested in ADS-B you can dump information from nearby aircraft
with a DTV stick and dump1090:

[https://github.com/antirez/dump1090](https://github.com/antirez/dump1090)

~~~
wglb
I use this and it is a lot of fun. However, to do well, you need an outside
antenna with good view of horizon.

Edit: And this is more fun: [http://www.flightradar24.com/free-ads-b-
equipment](http://www.flightradar24.com/free-ads-b-equipment)

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symmetricsaurus
Why not create a mesh network using the planes themselves. Surely most planes
must be in line of sight with several other planes even over the ocean. That
way they could broadcast their position among other things.

~~~
thebenedict
It sounds like ADS-B can do that:

"It does, however, have an air-to-air capability designed for use in
environments like the ocean that allows aircraft to “see” each other—the FAA
is now trying out this technique."

Sounds like it could work in much of the US and Europe, but planes are more
sparse in other parts of the world. Africa for example has minimal ADS-B
coverage and a relatively small number of planes in the air at once:
[https://flightaware.com/adsb/coverage](https://flightaware.com/adsb/coverage)

~~~
lucaspiller
I think the author is a bit confused by how this technology works. My
understanding is that an aircraft can also have an ADS-B receiver onboard,
which allows the pilot to identify other traffic in the local area - it
doesn't rebroadcast the signals as in a mesh network (I don't think there is
any encryption in these signals either, so that's probably a good thing).

ADS-B is only really used currently as a secondary resource for identifying
aircraft rather than seeing where aircraft are. The primary way is by using a
radar return, and matching this up with the aircraft transponder which reports
the aircraft ID and altitude.

At the moment I don't think there are any hard requirements on having ADS-B
transmission equipment on aircraft, although most commercial airliners already
have it (which is what FlightAware and such usually use - at least outside the
US). It will become a requirement over the next few years however for most
civilian aircraft.

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toomuchtodo
Iridiums is rolling out new satellites that have ADS-B receivers on board (for
open ocean data collection), and will be providing this data to the FAA for a
fee. Its a solved problem, but will take time to roll out.

[http://www.aireon.com/AboutAireon/AnIridiumInnovation](http://www.aireon.com/AboutAireon/AnIridiumInnovation)

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fragmede
What's more, here's a product that's already on the market, and has clear
pricing terms:

[https://www.ybtracking.com/products-yb3](https://www.ybtracking.com/products-
yb3)

The device is ~$600, and to have a 13 hour flight transmit a GPS signal every
5 seconds would cost another $600 per-flight - I'm sure the airlines could
negotiate a better deal.

Also note that they are currently available for purchase.

~~~
fixedd
You can't just slap any old device into an aircraft and call it done. There's
huge amounts of money + time that must be invested to get it certified, and it
has to be done for each aircraft type. I haven't looked it up, but I'd wager
an Iridium transmitter for transport aircraft would be in the 10s of thousands
of dollars, minimum.

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joshgel
"instead, air navigation service providers like the FAA would pay to use"
these new tools.

Seems like an appropriate government objective, but instead of just doing it
themselves, govt will end up overpaying some private company with the right
connections.

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gol706
I don't know how may aircraft are flying over these areas of open ocean at a
given time, but could some sort of mesh network be created?

Or perhaps ADS-B receivers could be placed on buoys like the ones used for
tsunami detection?

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peteratt
It blows my mind that I can turn on my phone, go to some mapping app and get
more accurate and frequent position updates than a commercial airplane. It's
just absurd.

~~~
jarek
With GPS, the hard part isn't figuring out where you are, it's telling the
rest of the world where you are.

~~~
UhUhUhUh
A lat/long position is about 50 bits. Talk about serious bandwidth...

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sambeau
Oceans are huge. Where do you send those 50 bits if you are 1000s of miles
from anywhere?

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jordanthoms
Satellite. The so-called cost concerns are just stupid, if I can afford a
satellite phone airlines can afford to report 50 bits to satellite every 30
seconds.

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ikeboy
Does anyone have a good breakdown for the claims I've seen elsewhere that
tracking every plane would cost billions?

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bartwe
gps+iridium uplink ?

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perlgeek
... and the iridium uplink, which is presumably expensive, only as a fall-back
if normal HF communication is available.

~~~
laxatives
Expensive relative to what? The consumer grade iridium device is only ~$1000.

~~~
mikeash
Per-minute or per-byte charges are also really high. But that's "high"
relative to individuals, maybe not compared to operating an airliner.

~~~
laxatives
I'm not sure about the details of the plan, but iridium offers unlimited data
for something like ~$100/month. I'm sure bandwidth is terrible, but again,
these costs are small, even for individuals.

~~~
mikeash
That's impressive! I severely overestimated the current cost of the service.
Here's a page with good info for the curious:
[http://www.groundcontrol.com/Iridium_Go.htm](http://www.groundcontrol.com/Iridium_Go.htm)

