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by toomuchtodo 697 days ago
> you need a redundant backup navigation system that is robustly deployed and reliably works.

Could existing cellular network base stations be this ground based backup navigation system?

https://people.engineering.osu.edu/sites/default/files/2022-...

2 comments

No. After about 5000 ft AGL (give or take) you can't pick up cell tower signals at all, since the antennas are directional and pointed towards the ground.

This is a deliberate design decision, because even a low-altitude aircraft would have hundreds of cell towers in sight and would overwhelm the network when handsets tried to register on all of them.

But also: Pilots like being able to have guarantees about system accuracy. We get notices anytime even a single GPS satellite is out of service (even though there are 31 of them), and have software tools in the aircraft to predict if there will be any signal degradation along our route (RAIM). I can't imagine having anything near that level of guarenteed safety with an ad-hoc system like described.

Sure it could be done but good luck convincing cell phone vendors to adopt liability for aircraft safety