euesa1-8, Exercise 2: Everyday dependence

Model answer:

Everyday things (any two): phone maps and navigation; aircraft approaches and landings (with EGNOS corrections); ship and vehicle tracking; mobile phone networks, financial trading and electricity grids keeping their clocks aligned.

Precise time matters because many systems must agree on exactly when something happened, and navigation satellites carry very accurate atomic clocks whose signals are used as a source of time. A fault in the time source can affect many systems at once, as the 2019 Galileo outage showed (check the details).