[SystemSafety] GPS jamming

Dewi Daniels dewi.daniels at software-safety.com
Fri Jul 12 12:57:04 CEST 2019


Mike,

That is very puzzling and worrying. I would have expected a Cessna Citation
560XL flying IFR to be fitted with a WAAS receiver. My understanding is
that WAAS was intended to detect spoofing as well as jamming. The WAAS
specification states, "WAAS provides the additional accuracy, availability,
continuity and integrity necessary to enable users to rely on GPS for all
phases of flight, from en route through approaches with vertical guidance,
at all qualified airports within the WAAS LPV coverage area". Either the
equipment on the aircraft was not working as intended, or WAAS itself does
not work as intended. I would have expected either possibility to be
investigated with some urgency.

Yours,

Dewi Daniels | Director | Software Safety Limited

Telephone +44 7968 837742 | Email d <ddaniels at verocel.com>
ewi.daniels at software-safety.com

Software Safety Limited is a company registered in England and Wales.
Company number: 9390590. Registered office: Fairfield, 30F Bratton Road,
West Ashton, Trowbridge, United Kingdom BA14 6AZ


On Fri, 12 Jul 2019 at 11:21, Mike Rothon <mike.rothon at certisa.com> wrote:

> The incident report is available on the NASA ASRS database at
> https://asrs.arc.nasa.gov/search/database.html. Search by Report Number
> (ACN) for 1565516.
>
> It was a Cessna Citation 560XL, a mid-size business jet. These are
> reasonably well equipped, usually a single or dual Honeywell Primus 1000
> package (when built).
>
> I thought this system was capable of DME/DME as well, but I have no idea
> how the solution would be compared or prioritised against a solid WAAS
> signal.
>
> It would seem that the action was more 'spoofing' rather than jamming, so
> probably the avionics thought it was getting a good signal (I'm speculating
> here though).
>
> It is worth noting that the report was made by a qualified controller. His
> / her assessment is quite definitive and chilling really.
>
> Mike
>
>
> On 12/07/2019 10:40, SPRIGGS, John J wrote:
>
> Hi Dewi,
>
> The original article does not tell us enough; if it were an airliner, it
> could not use ‘vanilla GPS’ and would have to have the RAIM capability
> mentioned in 1.7.1 of the document to which you linked.
>
> I suspect that it was one of those small aircraft that have a GPS antenna
> stuck to the windscreen, which can itself degrade the solution by occluding
> satellites.
>
>
>
> John
>
>
>
> *From:* systemsafety <systemsafety-bounces at lists.techfak.uni-bielefeld.de>
> <systemsafety-bounces at lists.techfak.uni-bielefeld.de> *On Behalf Of *Dewi
> Daniels
> *Sent:* 12 July 2019 10:25
> *To:* The System Safety List <systemsafety at techfak.uni-bielefeld.de>
> <systemsafety at techfak.uni-bielefeld.de>
> *Subject:* Re: [SystemSafety] GPS jamming
>
>
>
> I'm puzzled. I thought the whole point of WAAS (and EGNOS) was that the
> pilot would be alerted if the GPS calculated position is inaccurate. See
> section 1.7.2 of
> https://www.gps.gov/technical/ps/2008-WAAS-performance-standard.pdf . Why
> was the pilot not alerted in this instance? Was he not using a WAAS
> receiver? If not, why was he relying on a vanilla GPS receiver for
> navigation?
>
> Yours,
>
> Dewi Daniels | Director | Software Safety Limited
>
> Telephone +44 7968 837742 | Email d <ddaniels at verocel.com>
> ewi.daniels at software-safety.com
>
> Software Safety Limited is a company registered in England and Wales.
> Company number: 9390590. Registered office: Fairfield, 30F Bratton Road,
> West Ashton, Trowbridge, United Kingdom BA14 6AZ
>
>
>
>
>
> On Wed, 10 Jul 2019 at 12:49, Robert P. Schaefer <rps at mit.edu> wrote:
>
> Thought this would be of interest:
>
>
>
> NASA report: Passenger aircraft nearly crashes due GPS disruption
>
>
>
>
> https://www.gpsworld.com/nasa-report-passenger-aircraft-nearly-crashes-due-gps-disruption/
>
>
>
> Along the lines of “Who the heck would jam GPS in the continental US?”,
>
> I’ve got an anecdotal story from one of Haystack’s scientists who was
> trying to collect GPS data
>
> (L1, L2 data is useful for measuring solar activity in the Ionosphere)
> during the solar eclipse in August 2017.
>
> He was unable to collect data because of GPS jamming. The story was that
> truckers use GPS jammers so they
>
> won’t be tracked by their employers.
>
>
>
> bob s.
>
> research engineer
>
> MIT haystack observatory
>
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