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Newsgroups: comp.lang.ada
Date: Thu, 18 Apr 2019 02:45:08 -0700 (PDT)
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Subject: Re: Boeing 737 and 737 MAX software
From: tranngocduong@gmail.com
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Xref: reader01.eternal-september.org comp.lang.ada:56151
Date: 2019-04-18T02:45:08-07:00
List-Id: <comp.lang.ada>

On Thursday, April 18, 2019 at 12:27:44 AM UTC+7, Maciej Sobczak wrote:
> > I know nothing about the software.
>=20
> Me neither, so we are in a perfect condition to discuss it!
>=20
> > But I don't think it is written in Ada. If it was, programmers must hav=
e chosen a wrong subtype.
> >=20
> > In the crashed Ethiopian 302 aircraft, ~30 seconds before impact, the n=
ose points 40 deg. toward ground, and the AoA indicates 75 deg. As 40 + 75 =
=3D 115 > 90 deg., this would imply negative airspeed.
>=20
> So how would Ada help in this situation?
> What if the above addition is never performed? Because, you know, the res=
ult of this addition indicates a flight parameter that either nobody cares =
about or that is already obtained by other (presumably more reliable) means=
?
>=20
> In which case Ada would be a perfectly valid language there.
>=20
> --=20
> Maciej Sobczak * http://www.inspirel.com

The addition computes airspeed. More specifically it computes the elevation=
 angle, one of the 3 components of the airspeed (as a vector in 3-dimension=
al space), quite a critical flight parameter.

True, airspeed needs not be computed this way. But it must be somehow compu=
ted. All flight parameters must be somehow computed. If not for flying, the=
n at least for monitoring. The software is supposed to run on multiple (red=
undant) computers, takes input from multiple (redundant) sensors, computes =
flight parameters using multiple (redundant) algorithms.

True, it is possible that the software was written in Ada. But then, the fa=
ct that it didn't raise an exception (or even worse, programmers managed to=
 find a proof that it can never raise one), indicating a failure to detect/=
handle so "exceptional" situations as AoA implying negative [horizontal] ai=
rspeed, is simply unbelievable.