Re: Ada / Boeing 777

[Sam Harbaugh <harbaugh@ACUSYS.COM>]

Tim Rowe <digitig@CIX.COMPULINK.CO.UK> wrote:
>As an example, there was a known fault on one of the Airbus range (which
>has been flying total fly-by-wire for *many* years before the 777!) that
>meant that when flying a heading of 00 degrees, if the pilot commanded
>the aircraft to turn a bit one way, the aircraft could actually turn the
>other way. It was turning to the correct heading, but it was going the
>359 degree route, not the 1 degree route. Now, there are not many runways
>in the world that are close to north-south, but there are a few, and when
>that bug showed itself on a final approach I bet the pilots pants turned
>brown.

Point of order:  heading zero is invalid in the user space.  north-south
runways are marked 36 for 360 degrees, not zero.  Pilots and ATC speak of
360 degrees, not zero degrees.

I wouldn't suggest that this point has anything to do with the malfunction
but maybe, just maybe, if the programmer had a pilot's license he/she would
have known this and then maybe, just maybe, he/she would have known to turn
in the proper direction.

Just maybe, just possibly maybe, if the code was written in a strongly typed
language, using human readable names, and a pilot attended a code
walkthrough, the pilot would have picked up on type heading_type being from
0..359 instead of 1..360 and started a conversation that would have lead to
discovery of the worong way turn.

I wonder what language would provide this feature :-)

sam harbaugh  harbaugh@acusys.com
p.s. does this remind you of the "two values for midnight" thread of years ago?