Re: Ada and Automotive Industry

[Ingemar Persson <m-38530@MAILBOX.SWIPNET.SE>]

Regarding Chris Hills claims on 22 November about Ada causing the
destruction of the first Ariane 5.

There was no fault that can be linked to Ada. The software performed
exactly what it was designed to do. The real problem was that they kept
a program designed for Ariane 4 without any change. This program had no
meaningfull purpose after take off on Ariane 5 (it operates up to 40
seconds after take off on Ariane 4 in order to allow short holding
periods in the countdown). The result was that the software encountered
a situation it was not designed for (a higher velocity than Ariane 4).
The resulting numerical overflow led to the shutdown of both the two
systems (related to inertial guidance) simultaneosly. The real misstake
of the french team was that they had skipped a proper handling of an
numerical overflow (forgeting that they where dealing with a faster
object) and thereby allowing a program (that should have been stopped at
take off anyway) to stop two parallell systems.

The proper conclusion is that the french team made two mistakes that
together caused the destruction of Ariane 5, choosing Ada was not one of
them.

Please
to the fact that they are using Ada