[SystemSafety] SIL ratings to be scrapped?

Mon Aug 26 10:11:17 CEST 2013

Actually, it is not IEC 61508 vs DO 178. It is, of course, both !

Bertrand RICQUE
Program Manager, Optronics and Defense Division

T +33 (0)1 58 11 96 82
M +33 (0)6 87 47 84 64
23 avenue Carnot
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http://www.sagem-ds.com<http://www.sagem-ds.com/>

[cid:image001.jpg at 01CEA244.982301F0]

From: Matthew Squair [mailto:mattsquair at gmail.com]
Sent: Monday, August 26, 2013 10:08 AM
To: RICQUE Bertrand (SAGEM DEFENSE SECURITE)
Cc: systemsafety at lists.techfak.uni-bielefeld.de
Subject: Re: [SystemSafety] SIL ratings to be scrapped?

'Luckily', I'd put more faith in the landing gears software being designed and coded by the landing gears maker than their use of 61508 versus DO-178 :)).

Having worked as a primes safety manager on a couple of projects my lesson learned is that driving the subcontractor to use a different process/standard often delivers sub-optimal results. Better to understand their processes and address weaknesses as you see them.

And as no bid manager likes a 'do not comply' or 'comply with qualifications' there's intense pressure on the technical team during tender dream time to say 'yes we can', even when they don't really understand the implications. This is another engine that drives 61508 take up.

On Monday, 26 August 2013, RICQUE Bertrand (SAGEM DEFENSE SECURITE) wrote:
This is pretty true and I would even derivate another scenario.

You are the US Army, you have your own local plugs different from others and you don't care because you are number one customer and thus have plenty of suppliers adapting their equipment to these plugs at their own cost. You decide that your purchase deparment must be externalised and give them plenty of requirements such as: be careful to write state of the art specifications, etc... The purchase department that doesn't care and know anything about plugs looks for the plug standards and find that there is an international standard and just list it in the requirements !

This is exactly what happened with Boieng and IEC 61508 for landing gears of the 787...

Bertrand RICQUE
Program Manager, Optronics and Defense Division

T +33 (0)1 58 11 96 82
M +33 (0)6 87 47 84 64
23 avenue Carnot
91300 MASSY - FRANCE
http://www.sagem-ds.com

-----Original Message-----
From: systemsafety-bounces at lists.techfak.uni-bielefeld.de<javascript:;> [mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de<javascript:;>] On Behalf Of Peter Bernard Ladkin
Sent: Saturday, August 24, 2013 8:57 AM
To: systemsafety at lists.techfak.uni-bielefeld.de<javascript:;>
Subject: Re: [SystemSafety] SIL ratings to be scrapped?

Matthew,

On 8/24/13 5:55 AM, Matthew Squair wrote:
> That take up may be based more on a lack of understanding of its utility in non process control
> domains (low IMHO) or a judgement that it's an easy 'compliance = safety' argument that can be sold
> to defence customers who love a standards approach...
>
> On Friday, 23 August 2013, RICQUE Bertrand (SAGEM DEFENSE SECURITE) wrote:
>
>     It is interesting to see this evolution in UK while at the same time the major defense operators
>     (DCNS, Nexter, EADS, .) in France are adopting IEC61508 straightforward and including it in
>     their requirements, included for retrofits .____

To the contrary, it is based not on any lack of understanding but on straightforward market mechanisms.

Suppose you want to buy a washing machine, a very good washing machine, maybe the best. Then you
might look to Miele, just down the road from us (there is a plant here too, but washing machines are
down the road). It comes with a plug for German-standard house electricity supply. Suppose for the
sake of this analogy that changing the plug is *very expensive*, costs, say, on the order of the
price of the machine itself. And it's not just a washing machine you want, but all other household
kit too, from other countries as well as Germany and your own. Now, nobody else's plugs fit your
sockets and your plugs don't fit theirs. What do you do? Well, first you give thanks that you're all
on 230-250V and 50-60Hz. Then you don't pay for all those plug changes, you just go buy adaptors.
Because otherwise it would cost you twice as much.

This only works, though, if (a) the common grid values are some approximation to an adequate
electricity supply, and (b) there exist adaptors.

Here is the translation. Common grid values = international standard. Local plugs/sockets = local
military procurement standards.

Most major defence contractors have multiple clients. Most have, let us say, First Customers: the
First Customer of a US company is the US military, that of a French company the French military, of
an Indian company the Indian military, and so on. Successful military equipment suppliers supply
clients other than their First Customer.

Clients want kit developed to a standard, preferably their own. Suppliers have developed kit to a
standard, or multiple standards, but not necessarily the one Client uses, unless Client is the First
Customer.

So what is going to happen? Client wants to buy; Supplier wants to sell. It's going to happen, hope
both parties, but there is that pesky thing about standards conformance, which is usually a legal
requirement.

Somebody is going to have to put up the resources (i.e., pay) for Supplier's kit to be retroassessed
to Client's standard. This can cost huge amounts and be very tricky. For example, the UK military's
attempt to retroassess the C130J was a massive attempt involving innovative engineering methods and
can only be regarded as partially successful (see the German/Daniels project on the SW, for
example). And the entity putting up resources is ultimately Client. If you screw up the contract,
for example on Mk 3 Chinooks, Client doesn't get the info it needs to assess conformance to local
standard and consequently cannot use the kit as desired.

One might thereby think it useful for Client to have a local law which says: if it's US MIL STAN
it's good enough for us. But that is not what local law says in most developed countries. And there
may be good reason for that - it may not be true! See, for example, the controversy over the quality
of the aforesaid C130J SW. And, besides, such a law only works for Supplier from a specific country.
You'd have to have a similar Client law for other countries with Suppliers, and then Client would
basically be saying "if it's developed to some military standard somewhere, it's good enough for
me". But would such an attitude be enough to assure fitness for local purpose? Who knows? And
counterexamples abound. Look up, for example, "Chinook" and "Mull of Kintyre" and read doubts
expressed by UK military investigators about the quality/safety of the control system of one of the
world's workhorses.

So what's easiest and cheapest while being effective? There is an international civil standard, for
better or worse. Suppose Client has good local understanding of how its local standard relates to
that international standard; maybe even has a rough translation algorithm, leaving out some Sharp
Points. Suppose Supplier has developed kit to that international standard and provides the
accompanying documentation. Then Client pays locally for the transla#
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