The Nimrod Review - Official Documents

10B.15
10B.16
Chapter 10B – Nimrod Safety Case: The Facts (Third Phase)
– 6 Hazards have been assessed as HRI ‘B’. It is recommended that IPT accept these hazards
as closed at a probability of REMOTE, by being adequately managed ALARP without further
recommendation being proffered.
– 32 Hazards of which the majority are of the Zonal Hazard type, remain OPEN as probability
of UNCLASSIFIED due to DA being unable to identify sufficient evidence for a robust and
meaningful probability. Towards closure, it is recommended that IPT consider the ANNEX
C Section C2 table 1 recommendations against these respective Open Hazards.” (emphasis
added)
The Conclusion also had the following subtly different formulation of the statement which appeared in the
Executive Summary: 3
“From the above, it is thus declared that all potential hazards have been identified, assessed
and addressed to ALARP (subject to consideration of the proferred recommendations) and
that all appropriate standards had been met. Accepting this the top level goal of the
Nimrod MR Mk2 type Equipment Safety Case that
“The aircraft type is deemed acceptably safe to operate and maintain within
specified contexts”
is considered as having been demonstrated as having been achieved.” (emphasis added)
There was also no mitigation evidence of any sort included in either of the BLSC Reports. There was, therefore,
no basis upon which the Nimrod IPT or QinetiQ could check and satisfy themselves that BAE Systems had
used appropriate mitigation evidence to sentence the hazards.
Annexes to BLSC
10B.17
The BLSC Phase 2 Report for the MR2 ran to 46 pages, and had attached several lengthy Annexes including:
Annex A, “Fault Tree Analysis Accident Model” (42 pages); Annex B, “Summary of Hazard Risk Indices against
Nimrod MR Mk2 Identified Hazards” (9 pages) and Annex C, “Summary of Nimrod MR Mk2 Recommendations
made within this Safety Case Baseline Project” (26 pages).
10B.18 Annex B stated in relation to Hazard H73 (one of the 32 open hazards left “Unclassified”):
HAZARD I/D
ZONE
DESCRIPTION
H73 Zone 513/613
Interacting
System
Hazards – No.
7 Fuel Tank
3 Page 46 of the BLSC Report on the MR2.
SEVERITY PROBABILITY HRI
RECOMMENDED
HAZARD STATUS
CATASTROPHIC UNCLASSIFIED – OPEN
243