[tz] GPS Week Number Rollover Apr 6/7

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Tue Apr 2 04:00:03 UTC 2019

On 2019-04-01 17:41, Paul Eggert wrote:
> On 4/1/19 1:28 PM, Brian Inglis wrote:
>> If my script is correct, the rollover occurs at the indicated instant on the
>> time scales below:
>> 2019 Apr 06 Sat 23:59:42+0000
> That hits a bit close to home, as I'm scheduled to take a US commercial
> flight that will take off about two hours after that.
> As it happens in my software engineering class today I talked about
> AeroData's nationwide outage this morning, and now you're prompting me
> to speculate whether that outage was related to the GPS rollover.
> Although AeroData hasn't said publicly what caused the problem, the
> Orlando Sentinel reports that it was related to GPS and it's not beyond
> the realm of possibility that a flight-planning application would use
> prospective GPS clocks that wrapped around. (Of course I'm just guessing
> and could easily be quite wrong.) See:
> Pedersen JM. Nationwide glitch impacts flights at Orlando airport;
> Southwest, JetBlue most affected, official says. Orlando Sentinel.
> 2019-04-01 08:05 -04.
> https://www.orlandosentinel.com/news/breaking-news/os-ne-oia-aero-data-glitch-20190401-story.html
> The outage caused hundred of US flights to be delayed today. See:
> Gallagher S. Flight management system crash causes airline delays across
> US. Ars Technica. 2019-04-01 16:34 -00.
> https://arstechnica.com/information-technology/2019/04/flight-data-system-outage-causes-april-1-airline-delays-no-fooling/

>From the Ars commentary, I'd be worried about any airline using date, software,
or services from AeroData Inc. for flight performance, weight, and balance
planning, given the apparent lack of attention or care to maintenance of their
If there is any "GPS" component, I would expect that it because of the North
American tendency to use GPS to refer to satellite augmented navigation systems
(SatNav in Europe) or any systems using GNSS in general. In this case it might
refer to provision of navigation information, calculating and generating
waypoints and markers for flight tracks, with runway, heading, gradient,
temperature, beacon, marker, control frequency, fuel load and usage, weight, and
balance annotations.
Their name appears in a case study by VMware: they apparently didn't use it
effectively regardless of the cause of their issues.

One frequent flyer posted "Delta mainline (and American) was not hit because
they don't use their takeoff data from AeroData. Delta Connection as well as
Southwest, Frontier, United, and JetBlue were impacted".

They don't appear to be the kind of people from whom you could expect a good
pull request, or one which you might care to accept. ;^>

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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