[SystemSafety] GPS jamming

Mike Rothon mike.rothon at certisa.com
Fri Jul 12 12:21:55 CEST 2019

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 

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.


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> *On Behalf Of 
> *Dewi Daniels
> *Sent:* 12 July 2019 10:25
> *To:* The System Safety List <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 
> <mailto:ddaniels at verocel.com>ewi.daniels at software-safety.com 
> <mailto: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 
> <mailto: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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