Anything in a regulated industry such as aerospace tends towards the process heavy. Our requirements get tracked in our QMS system that ensures we're AS9100-compliant. There's a final test-for-credit step after which the software part should be considered hermetically sealed. Any software change requires a new test-for-credit round that likely takes an extensive amount of time.

So, in short, developing for aerospace is not agile. :-) It's the Niagara Falls of waterfall methods.