[SystemSafety] USAF Nuclear Accidents prior to 1967

From: Peter Bernard Ladkin < >
Date: Sat, 21 Sep 2013 19:36:44 +0200

The Guardian today has an article on an accident to a US B-52 bomber in North Carolina in 1961. The aircraft, suffering a mid-air break-up, released two nuclear weapons, which were armed. One of the bombs was, according to a book by Ralph Lappe, "equipped with six interlocking safety mechanisms, all of which had to be triggered in sequence to explode the bomb. ...Air Force experts....found that five of the six interlocks had been set off by the fall! Only a single switch prevented the 24 megaton bomb from detonating..."

This quote is contained in a short memo by Parker F Jones, an analyst at Sandia Labs, written in October 1969. He deprecates Lappe's general account but says that on this point he is correct; emphasises the vulnerability embodied by the switch, its type and function (it does not appear to have been adequately assessed for reliability in an accident scenario) and concludes that this type of bomb "did not provide adequate safety for the airborne alert role in the B-52." and footnotes that the "same conclusion should be drawn about present-day SAC bombs."

This is all contained in an article in The Guardian at http://www.theguardian.com/world/2013/sep/20/usaf-atomic-bomb-north-carolina-1961 Jones's memo is presented at

This is due to Eric Schlosser, who is about to publish a book called Command and Control. Schlosser has visited facilities, and so on, and gave an interview to The Guardian at http://www.theguardian.com/books/2013/sep/21/eric-schlosser-books-interview Apparently, he made an FOIA request for all the incidents in the 10 years to 1967, and received 245 pages of them.

Scott Sagan made similar inquiries in his 1993 book The Limits of Safety, for which he is justly famous. I didn't find the incident in Scott's book, so asked him if he knew about it. Scott's thesis in that book was testing Charles Perrow's Normal Accidents theory against the high-reliability-organisation theory of La Porte and colleagues.

The NA hypothesis is that tightly-coupled interactively-complex systems are unavoidably vulnerable to accidents which occur while everything is operating "as designed". The HRO theory says that there are certain characteristics of complex organisations which have proven to have had high reliability. One example of such an organisation is USN peacetime carrier operations (launching and retrieval of aircraft); another is Pacific Gas and Electric's nuclear power plant operations (which was a bit of a surprise to us who lived through part of the Diablo Canyon controversy).

USAF has obviously not had an accident in which a nuclear weapon has been accidently detonated. The question therefore was whether USAF SAC exhibited the characteristics of a La Porte HRO. Sagan argued that such accidents had been avoided through happenstance, and that the history rather supported the NA theory. It seems from the advance commentary that Schlosser's book will make a similar case.


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

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Received on Sat Sep 21 2013 - 19:36:50 CEST

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