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<p class="MsoNormal">> W&B calculations on commercial aircraft are an example of a critical process<o:p></o:p></p>
<p class="MsoNormal">I wonder how well that is internalized and not just “known” by the people that create, maintain, and use the W&B calculation tools and processes. (“Someone once told me that W&B calculations are critical to safe flight.”) I can see that
easily being lost when all W&B calculations are done in backroom computers at an airline’s operation center, along with a lot of other non-critical airline data processing. I once saw all NWA planes in the take-off que at SEA get pulled to the side (~90%
of the dozen of planes in the que) because their W&B computer (in TN?) went down.<o:p></o:p></p>
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<p class="MsoNormal"><b>From:</b> systemsafety <systemsafety-bounces@lists.techfak.uni-bielefeld.de>
<b>On Behalf Of </b>Nick Tudor<br>
<b>Sent:</b> Tuesday, April 13, 2021 3:54 AM<br>
<b>To:</b> Peter Bernard Ladkin <ladkin@causalis.com><br>
<b>Cc:</b> systemsafety@lists.techfak.uni-bielefeld.de<br>
<b>Subject:</b> [External] Re: [SystemSafety] Miss vs Ms<o:p></o:p></p>
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<p class="MsoNormal">Memory is a little fuzzy and no doubt others may have better. There was an unauthorised use of a spreadsheet to do v1/v2 calculations for an E3 AWACS aircraft some many years ago I believe that there was an issue with the V1 speed as
rotation at too low a speed meant that V2 couldn’t be reached. It ran out of runway. <o:p></o:p></p>
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<p class="MsoNormal">On Tue, 13 Apr 2021 at 08:11, Peter Bernard Ladkin <<a href="mailto:ladkin@causalis.com">ladkin@causalis.com</a>> wrote:<o:p></o:p></p>
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<br>
On 2021-04-13 02:02 , Bruce Hunter wrote:<br>
> <br>
> The interesting thing was that this was indirectly a result of updated software errors in an update
<br>
> to the off-board load balancing computer on a PC (ALPAC). Great lesson that dangerous software
<br>
> failures may not just occur on integrated systems but on separate ancillary equipment as well. You
<br>
> really need to check whether safety functions are dependent on external <br>
systems reliability as well <br>
You sure do.<br>
<br>
W&B calculations on commercial aircraft are an example of a critical process in which data and their
<br>
accuracy are key. Not only is the SCSC Data Safety Guidance relevant, but <br>
so are other routine <br>
cross-checks well known in computer science.<br>
<br>
After an Emirates A340 narrowly avoided becoming a horrendous accident on <br>
takeoff from Melbourne in <br>
2009, Bernd Sieker and I wrote a short note explaining how such data safety procedures, input and
<br>
processing, could be improved. (It seems we sent it to HESSD, but I am not sure HESSD was held that
<br>
year.)<br>
<br>
A decade on, trivial design/programming errors are apparently still making it into such
<br>
safety-related software.<br>
<br>
PBL<br>
<br>
Prof. Peter Bernard Ladkin, Bielefeld, Germany<br>
ClaireTheWhiteRabbit RIP<br>
Tel+msg +49 (0)521 880 7319 <a href="http://www.rvs-bi.de" target="_blank">www.rvs-bi.de</a><br>
<br>
<br>
<br>
<br>
<br>
_______________________________________________<br>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">Nick Tudor <o:p></o:p></p>
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<p class="MsoNormal">Tudor Associates Ltd<o:p></o:p></p>
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<p class="MsoNormal">Mobile: +44(0)7412 074654<o:p></o:p></p>
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<p class="MsoNormal"><a href="http://www.tudorassoc.com" target="_blank">www.tudorassoc.com</a><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#00144D">Malvern</span></b><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#00144D">Worcestershire</span></b><o:p></o:p></p>
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