I was under the impression that GPS was a non-critical asset for aviation, ie. any plane can safely stop using it at any given time and keep flying with VOR and other navigational aids.
This article [1] introduces some of the scenarios where pilots rely on GPS only:
* GPS-based waypoints to optimize routing based on favorable winds and more direct routes even in the absence of VORs.
* RNAV departures and arrivals that rely "solely on GPS rather than radio-based [...] aids" with more precise spacing and hence higher capacity.
* GPS used as a substitute of ILS for some approaches e.g. in mountainous areas.
I would assume its not 'safety critical' but 'business critical', disabling GPS would mean slowing down departures / arrivals which means the airport losing money. I recall there being a similar issue with Lufthansa and SFO causing planes to get rerouted to oakland.
There's a meme driver with safety vs business critical and software types seem to think they're special (a different meme) but I'm starting to understand it's everywhere, which is why nobody notices the software issue creeping into their physical systems thinking.
A "business critical" issue is defined by the appetite for risk. Most businesses aren't planning for total economic collapse: losing their accounts receivable is what that would look like. What they are concerned about is losing business to competitors or liability for not fulfilling contracts. Software seems to solve the latter problem with shrinkwrap agreements "not responsible for failure of software". That solves their liability problem; everybody else they'll sue.
On the other hand "safety critical" concerns the loss of life or property: the things insurers are traditionally concerned with. So if the plane can land, engine out or GPS out what's the difference? Businesses absolutely care about safety, that's why they buy insurance! Safety programs reduce the need and cost for such insurance.
Businesses aren't lying when they say they care about safety. However people swim in the ocean of systems without necessarily being systems thinkers: plugging a leak is plugging a leak. But a leaky roof is not the same as a leaky hull. All the people in cybersecurity warning of the dire consequences of breaches are proven wrong time and again by the market: look at the stock prices of Equifax, Solarwinds, United Health Care. It's not simply marketing, a lot of these people really Want To Believe (tm).
In the end business is never safe, it's taking risks all the time. Mostly it doesn't see a need to share those risks with customers (or competitors).
This article [1] introduces some of the scenarios where pilots rely on GPS only:
* GPS-based waypoints to optimize routing based on favorable winds and more direct routes even in the absence of VORs.
* RNAV departures and arrivals that rely "solely on GPS rather than radio-based [...] aids" with more precise spacing and hence higher capacity.
* GPS used as a substitute of ILS for some approaches e.g. in mountainous areas.
[1] https://simpleflying.com/gps-in-aviation-pilots-guide/