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The risk these things pose to aviation is real. There's been a huge shift towards GPS for instrument flying. Cross country flying frequently relies on GPS to kn

The risk these things pose to aviation is real. There's been a huge shift towards GPS for instrument flying. Cross country flying frequently relies on GPS to know where you are. Even more important, flying an approach to land now often uses GPS to keep the plane to a specific safe path, essential when flying in a cloud. A plane isn't going to fly out of the sky if GPS suddenly stops working, but it can make life awfully difficult. The risk is not just theoretical. For example, in 2009 the Newark airport had a daily GPS failure that was finally traced to a trucker using a jammer, presumably to defeat a tracker enforcing safe driving rules. http://www.economist.com/node/18304246 http://www.economist.com/node/18304246

gatlin 14y ago
I just saw a demonstration a few days a go by the UT Austin Radio Navigation lab where they spoofed L1 GPS and caused a radio controlled helicopter to somewhat precisely veer off course. I'm interested in the impact of this on aviation as well.
zbowling 14y ago
The more sophisticated jammers don't cause "noise", but rather they record and replay the pseudorandom generated digits they receive from the various frequencies and time drift them. It's hard to triangulate much of anything then and it could send you off miles from where you think you are. Much better than just noise because you wouldn't know there is a problem.
- NelsonMinar 14y ago
  This attack is what Iran says they did to capture the US drone a few months ago. It's pretty crazy that GPS signals include no cryptographic authentication, even for military use. I'm not so worried about this kind of attack on civilian aviation. It would be a directed attack: potentially deadly but rare and focussed. I'm much more worried about the casual disruption to GPS from truck drivers spending $99 on a grey market device.
  - zbowling 14y ago
    There is cryptographic hash so that you can't send false data, but replaying the existing data but time delayed is still possible. The timing is how the triangulation fix is done. More sources of data, the harder it is to spoof. If you only have 3 or 4 fixed points, it's easy to spoof. 6 to 10 and it becomes extremely difficult. Also military GPS is far more accurate than civilian GPS by a factor of 10x.
    - ghshephard 14y ago
      "military GPS is far more accurate than civilian GPS" - is this still true? I don't know how my iPhone GPS triangulates me, but it usually has me located to within 3-5' at all times when I'm walking home.
      - zbowling 14y ago
        yep. the reason why your iPhone is fast has to do more with AGPS and that it can use wifi access points as references points as well.
        deleted 14y ago
        [deleted]
        blake8086 14y ago
        I believe that difference went away in 2000: http://en.wikipedia.org/wiki/Selective_Availability#Selective_availability http://en.wikipedia.org/wiki/Selective_Availability#Selectiv...
        maxerickson 14y ago
        Military hardware can access encrypted signals that provide greater precision: http://en.wikipedia.org/wiki/Global_Positioning_System#Satellite_frequencies http://en.wikipedia.org/wiki/Global_Positioning_System#Satel...
        14y ago

gatlin 14y ago

I just saw a demonstration a few days a go by the UT Austin Radio Navigation lab where they spoofed L1 GPS and caused a radio controlled helicopter to somewhat precisely veer off course. I'm interested in the impact of this on aviation as well.

zbowling 14y ago

The more sophisticated jammers don't cause "noise", but rather they record and replay the pseudorandom generated digits they receive from the various frequencies and time drift them. It's hard to triangulate much of anything then and it could send you off miles from where you think you are. Much better than just noise because you wouldn't know there is a problem.

NelsonMinar 14y ago
This attack is what Iran says they did to capture the US drone a few months ago. It's pretty crazy that GPS signals include no cryptographic authentication, even for military use. I'm not so worried about this kind of attack on civilian aviation. It would be a directed attack: potentially deadly but rare and focussed. I'm much more worried about the casual disruption to GPS from truck drivers spending $99 on a grey market device.
- zbowling 14y ago
  There is cryptographic hash so that you can't send false data, but replaying the existing data but time delayed is still possible. The timing is how the triangulation fix is done. More sources of data, the harder it is to spoof. If you only have 3 or 4 fixed points, it's easy to spoof. 6 to 10 and it becomes extremely difficult. Also military GPS is far more accurate than civilian GPS by a factor of 10x.
  - ghshephard 14y ago
    "military GPS is far more accurate than civilian GPS" - is this still true? I don't know how my iPhone GPS triangulates me, but it usually has me located to within 3-5' at all times when I'm walking home.
    - zbowling 14y ago
      yep. the reason why your iPhone is fast has to do more with AGPS and that it can use wifi access points as references points as well.
      - deleted 14y ago
        [deleted]
      - blake8086 14y ago
        I believe that difference went away in 2000: http://en.wikipedia.org/wiki/Selective_Availability#Selective_availability http://en.wikipedia.org/wiki/Selective_Availability#Selectiv...
        maxerickson 14y ago
        Military hardware can access encrypted signals that provide greater precision: http://en.wikipedia.org/wiki/Global_Positioning_System#Satellite_frequencies http://en.wikipedia.org/wiki/Global_Positioning_System#Satel...
        14y ago