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Comment by TeMPOraL | Hacker News Reader

Can someone explain to me why they can't just stick a GPS receiver wired to Iridium satellite phone and duct tape it to the back of the plane? I.e. it shouldn't be neither hard nor that expensive to send a few dozen bytes of telemetry every minute via Iridium. Why anything like this is not happening?

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They charge a lot of money for real-time telemetry from a plane. This charge can frequently represent the entire profit for a flight for smaller carriers, so they don't elect to purchase it.

Who is 'they'?

You don't even need Iridium, a shortwave radio transmitter will suffice.

Boeing or Airbus. Look up ACARS, it exists, many planes are equipped.

I find conflicting information about the Air Asia flight, a Bloomberg article claims the plane wasn't equipped, other places claim it was, but the airline wasn't subscribing to the data it generated.

It's not clear at all whether this is related to the cost of the system itself however.

Would it? Could you elaborate?

You don't need real-time (a small delay is OK) or much telemetry.

Just 10 bytes or so every 5-10 minutes.

And over land you can use cell phone tower, so smaller carriers (who don't go much over water) would not be impacted badly.

Actually over land you probably don't need anything at all, so this really would just impact those best able to handle the expense.

They are. New Iridium birds are going up with ADS-B receivers onboard, with the data relayed to the ground over the Iridium network.

http://www.aireon.com/AboutAireon/AnIridiumInnovation

Replacing orbiting equipment takes time and money.

I think this is the question everyone is wondering. But even in a minute a plane travels a huge distance. And also keep in mind the height at which they fly so assuming the planes don't stop going forward they can travel huge distances on their descent to the ground.

Nevertheless, I also wonder why this couldn't work and just send the data more frequently. I don't know anything about the GPS consumers connect to but if my TomTom can connect to a satellite in space and give me my location down to a few metres at a regular interval then why can't a plane do the same?

For what it's worth, GPS works because the satellites are broadcasting signals to earth, not your phone to space.

> But even in a minute a plane travels a huge distance. And also keep in mind the height at which they fly so assuming the planes don't stop going forward they can travel huge distances on their descent to the ground.

Even a few dozen bytes worth of data every minute about current position, heading, airspeed, heading and speed of the wind is enough to reduce this theoretical "huge distance" (that is much smaller than what people have to deal with without tracking data) to a relatively small cone that can be searched effectively.

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