[SystemSafety] The Accident to SpaceShip2

Peter Bernard Ladkin ladkin at rvs.uni-bielefeld.de
Mon Aug 3 14:14:49 CEST 2015


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

The NTSB held its public hearing on July 28th. All infos, including presentations from the
hearing, available at http://www.ntsb.gov/news/events/Pages/2015_spaceship2_BMG.aspx and the
NTSB's provisional executive summary, findings and safety recommendations at
http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_abstract.pdf

The NTSB is big on the HazAn not having dealt adequately with HF aspects, including that the
accident showed there was a critical system (the feather actuation/stow/lock/mechanism) with a
single point of failure, namely human error.

However, I strongly disagree with the "summary" of Alister Macintyre, who wrote about it in the
Risks Forum http://catless.ncl.ac.uk/Risks/28.83.html#subj1 He speaks about "cut[ting] corners",
and writes as if he thinks various people did things wrong. I don't see much evidence for that at
all (although it is possible that some might come with the full report). I see people trying to
get a job done, to bring a highly innovative piece of critical engineering - pioneering is an apt
word - to fruition. And in this largely novel environment, needing to improve their HazAn. The
HazAn is likely substantial intellectual property. Without evidence, it's on the verge of
insulting to suggest anyone or any group involved with this project was slacking.

Compare. Lithium-ion primary and auxiliary batteries on the Boeing 787 is also new technology. An
FMEA was done that suggested the worst that could happen to the environment during thermal runaway
of one or more cells was development of smoke. That FMEA remained unchanged even after a
thermal-runaway event during testing burnt down the test facility. And the NTSB visited the
fabricating factory where it observed that hazard mitigation, namely certain quality control
measures, was not as effective as was thought
http://www.ntsb.gov/investigations/AccidentReports/Reports/AIR1401.pdf . Boeing has a lot more at
stake - maybe the entire company again, who knows? - in getting it right than the backers of
Scaled Composites. And they still didn't get the HazAn right.

When the technology is new, HazAn is a tricky business. No one wants to get it wrong. But they do.
And they will. Which is why some of us are working on ways to get it done better.

I say more at http://www.abnormaldistribution.org/2015/08/03/the-accident-to-spaceship-two/

PBL

Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs.uni-bielefeld.de




-----BEGIN PGP SIGNATURE-----

iQEcBAEBCAAGBQJVv1s5AAoJEIZIHiXiz9k+TeUIAIQJFdC4U8GaTy/dp5Mc2o1i
43sQH6wtT0sCNDjGPGAeQtSYrqyfIyPnw8WJmUY4ZBHfJlLnlN0gkeR5f41/kK6T
WI/w1HzHuRX6vWtOIMkYHPmwm5c58frNFsDMu6/R+Egv21DnPy7qhVN4pajsNpPX
DwSselt2SiHD0ELd8SEfUgkALjYzfLNDIo9JKEVw8QgXinRHJqVPxeZsITHxBT1X
2YBdcsK3tpRB135yIAqYABsgE9Qe2aO3jQTwFi/3DPNG9EWSqqp8bjmFulDRYXtp
/nFoXJG9uX0LAKOwGqEQlK8UzYZotEa2GzkB1DK3ORBr+9lV+8vk5oGLvr/ibW0=
=JhzT
-----END PGP SIGNATURE-----


More information about the systemsafety mailing list