[SystemSafety] Difference between software reliability and astrology

[Prof. Dr. Peter Bernard Ladkin]

On 2024-08-22 10:42 , M Ellims wrote:
> The first thing to note is that the figure given is for electronic/electrical hardware and excludes software.

Not so. 14 CFR 25.1309 can be read at https://www.law.cornell.edu/cfr/text/14/25.1309  and we can 
see that it is not restricted.

Note that the European reg is similar but not identical.

> Guidance from the FAA is the software included in any FTA analysis should be assigned a failure rate of zero. The rational being that software failure rates are in general cannot be reliably estimated and thus the dependence/reliance on DO178.

That may be an "acceptable means of compliance" as EASA would say, but it is not what the regs say 
(see above).

PBL

Prof. i.R. Dr. Peter Bernard Ladkin, Bielefeld, Germany
www.rvs-bi.de