Re: would you fly on an Airbus that was being run by a Pi?
The ex top man at ARM is now top man at RR (aero engines):
Putting aside considerations like thermal and vibration, which relate to an implemetation rather than an architecture, there's an interesting discussion to have around whether RR engines should be controlled by a customer-specific tiny-volume DIY-architecture microprocessor design with customer-specific tools to match (as is proposed at the moment), with all the disadvantages that high complexity devices have in tiny volumes, or an environmentally hardened instance of a massive-market architecture and tool set that has had loads of real world testing as well as the stuff the aviation regulators require.
There were a number of reasons the RSRE's Viper microprocessor concept never caught on. There are parallels here.