Any assertion that software development teams can't make development mistakes is patently absurd.
I never made that claim. However the chance of software produced by two independent teams who have submitted two *completely* different implementations coming up with the same erroneous value has to be considered pretty damn remote.
Anybody who's subscribed to AW&ST knows aerospace has experienced a lot of these over the years. Even NASA lost two mars missions due to schoolboy errors in not converting values.
Not to disrespect NASA, but I think their coding standards were far less stringent than the teams writing Airbus and Boeing's control software.
And the old Airbus-Habsheim debate has been done to death. The crew screwed up. M.Asseline was way below alpha-floor protection height and the delay in spool-up time was caused *not* by the FADEC control commanding a gradual thrust increase (otherwise you'd have had multiple fatal failed go-arounds by now), but because the A320 uses high-bypass engines that do take a few seconds to spool up compared to the older low-bypass type. M.Asseline should have aborted the pass the second he went under 100ft RA.
The FBW protections did actually keep the A320 level when it hit the trees. Not only would a 747-200 not have survived a similar incident (it would never have been able to make that maneouvre in the first place - hence why Airbus were so keen on that demonstration), but without the protections the A320 had it would have probably augered into the trees wing-down and killed everyone.