The Nimrod Review - Official Documents

Chronology – three phases
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Chapter 10A – Nimrod Safety Case: The Facts (Phases 1 and 2)
The chronology of what took place during the drawing up of the NSC conveniently falls to be considered in
three phases:
(1) Phase 1 conducted by BAE Systems (April 2001 to April 2003): following the initial scoping of the NSC
task, the carrying out of the hazard identification task by BAE Systems (Phase 1).
(2) Phase 2 conducted by BAE Systems (August 2003 to September 2004): the carrying out of the hazard
analysis and hazard mitigation tasks by BAE Systems, and the handing over of the six NSC Reports by
BAE Systems to the Nimrod IPT (Phase 2).
(3) Third Phase conducted by the Nimrod IPT (November 2004 to March 2005): Following handing over
of the NSC Reports by BAE Systems to the Nimrod IPT and the ‘signing-off’ of the task (supported
by QinetiQ), the Nimrod IPT then proceeded to sentence the remaining hazards left “Open” by BAE
Systems, and the NSC for both Nimrod MR2 and R1 was declared completed in March 2005. 8
Phase 1 conducted by BAE Systems (April 2001 to April 2003)
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The Nimrod IPT determined early in 2001 to develop an ‘explicit’ Safety Case for the Nimrod fleet, and to task
BAE Systems to draw it up. Whilst, technically under BP1201, the Nimrod IPT could have relied on the Military
Airworthiness (MA) Release as an ‘implicit’ Safety Case, 9 it was clearly desirable for a ‘legacy’ platform of
the age of the Nimrod to have an ‘explicit’ Safety Case. BP1201 provided that a Safety Case must provide a
“credible” justification of safety and must be “consistent, complete and comprehensible”. 10
The scope of the NSC task to be carried out by BAE Systems was initially laid down by the Nimrod IPT in
a Post Design Services (PDS) Task Request Form sent to BAE Systems on 11 April 2001. 11 This outlined the
respective responsibilities within the IPT and RAF for the NSC, the strategy to be employed, and the scope of
BAE Systems’ involvement:
As to responsibilities, the following were to said to have key roles in developing the NSC: (1) all IPTs were
required to establish a Platform Safety Working Group (PSWG) “to develop and maintain” a platform Safety
Case; (2) the Nimrod IPTL would chair the PSWG and was responsible for the NSC; (3) the Nimrod Head of
Air Vehicle (NIM(ES)AV) was responsible for managing the development of the NSC on behalf of the IPTL; and
(4) the Fixed Wing Airworthiness Management Group (FWAMG) would “monitor” the implementation of the
NSC on behalf of the Defence Aviation Safety Board (DASB). I discuss later the extent to which, if any, of the
above, in fact, had any real involvement in the development of the NSC.
As to strategy, it was envisaged there would be four phases for Safety Cases for ‘legacy’ platforms: (1)
Phase 1: develop a strategy to construct the Safety Case; (2) Phase 2: develop a strategy for the ongoing risk
management of the Nimrod; (3) Phase 3: construct the Safety Case; and (4) Phase 4: manage the safety of
the Nimrod throughout its operational life.
As to BAE Systems’ involvement, it was envisaged that much of the work would be based on BAE Systems’
information as the aircraft DA. It was expected that BAE Systems Chadderton would “assess the level of
information currently available to it” and provide: (a) an initial “hazard assessment” carried out at system
level; (b) a detailed “Fault Tree” analysis at system level; and (c) a “safety assessment” detailing the findings
of the studies and assessing the risk of functional failures.
BAE Systems was given two initial tasks. First, to provide an initial assessment of the current availability of
appropriate Hazard Data and Fault Tree Analysis data, i.e. “how much data is readily available within the ADA
for the Nimrod Platform”. Second, to provide a business strategy to develop a Safety Case by 31 December
2002 and costings within 60 days, the overall scope of the work being envisaged as “considerable”. The
second task was carried out. The first was not.
8 E-mail from Frank Walsh to BAE Systems, dated 16 March 2005.
9 BP1201, paragraph 12.
10 Ibid, paragraph 9.
11 PDS Task Request Form number AV(PDS)814 drafted by the Nimrod IPT (NIM(ES)AV(PDS), SPTO).
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