[randomsearch]

> What was the motivation for switching to C?

Invariably, cost. SPARK Ada is demonstrably superior to C for safety-critical development (I can't cite the sources for this, but a major company developing safety-critical software has shown this to be the case).

But, SPARK Ada requires a lot of highly skilled manpower and it's slow to develop. C gets the job done, albeit with lots of bugs.

[cpeterso]

If the industry is unwilling to invest in the training or tooling for a safe language like SPARK Ada, is there research into "easier" safe languages, something between C and Ada? Or do companies like Boeing still expect to be writing new avionics safety in C in 2030 or 2040?

[randomsearch]

Yes, Real-Time Java being an example.

Realistically, it seems to me that avionics etc. will be written in C for a very long time to come. It all comes down to the cost and availability of programmers.