Originally Posted by
Mad (Flt) Scientist
All DAL-A assures is that the software does what the software requirements say it should do, not that those requirements are themselves correct or complete. That's a SYSTEMS requirements issue not a software requirements issue - and indeed, can be thought of as applying to non-software aspects of design as well.
Beg to differ a bit. DAL A assurance is supposed provide convincing evidence that requirements are validated, and that they are traced to the code. The process for establishing software Design Assurance Level A is painfully extensive in time and resources. It is not an absolute guarantee of no software errors because testing to prove that is not possible. But the process, developed by manufacturers and regulators together has been in use for decades, though not without attempts to push back. Hopefully, energy to resist pushback at the rigor of DAL processes will be renewed as a result of the MAX debacle.