OSA

1
OSA

• Operational Safety Assessment
• Notional Outline
• RTCA SC-206 MET Subgroup Meeting
• Exeter, UK
• June 11-16
• DM060806

2
OSA Guidance

• DO-264/ ED-78A Appendix E
• Draft of NGATS Safety Management Systems (Nov 8,
  2005)

3
OSA

• The OSA is part of the SPR Safety and
  Performance Requirements and ultimately the OSED
• Composed of two processes
• The OHA, Operational Hazard Analysis, and
• ASOR Allocation of Safety Objectives and
  Requirements

4
Hazard Definition

• Hazard According the NGATS SMS draft, a hazard
  is any existing or potential condition that can
  lead to illness, injury, or death to people
  damage to or loss of a system, equipment, or
  property or damage to the environment. A hazard
  is a condition that is a prerequisite to an
  accident or incident.
• A hazard is not equivalent to system failure, but
  may induce or manifest failure

5
OHA Objective

• OHA - Operational Hazard Assessment
• Objectives
• Determine system hazards and effects
• Classify the severity of hazard
• Assess risk and safety objectives

6
OHA Steps

• OHA - Operational Hazard Assessment
• Describe system in sufficient detail to determine
  hazards
• Identify provisioned services (for example, Short
  Term Decision Support service for FIS)
• Enumerate and analyze hazards in terms of effects
  (Classification matrix)
• Assess the hazard risk in terms of severity and
  likelihood (Hazard class and safety objective)

7
OHA Steps, cont.

• Primary operational hazards in the context of
  datalink are
• Loss or unavailability of information (all or
  part)
• Misleading or incorrect information ( see DO-264
  for all the variants)
• Ability to detect misleading or incorrect
  information

8
OHA Steps, cont.

• Effects are to be considered such as
• Loss of separation or margin of safety with
  respect to weather phenomena (i.e., volcanic ash)
• Loss of separation from other aircraft (i.e.,
  poor visibility obscuring aircraft on surface)
• Collision or loss of margin of safety with
  respect to terrain

9
OHA Steps, cont.

• Consideration given to effects factors such as
• Time of occurrence
• Flight crew workload
• Phase of flight
• Extent of effect in time and space

10
Hazard Classification Matrix
11
Hazard Class and Safety Objective Relationship
12
OHA Summary Template
13
ASOR Objectives

• Allocation of Safety Objectives and Requirements
• Primary objectives for all service categories
• Allocate/ apportion identified safety objectives
  to subsystems and processes
• Determine safety requirements
• Identify and validate safety risk mitigation
  strategies mindful of all stakeholders
• Each service category must be addressed

14
ASOR Objectives

• E.3.2 (8) fulfill the safety objective with a
  set of safety requirements that are identified
  with specific stakeholders

15
ASOR Steps - Allocate

• Allocate and apportion safety objectives among
  system elements

16
ASOR Steps - Require

• Determine safety related requirements of system
  as a whole and elements consistent with safety
  objectives (for example, undetected received
  data error rates shall be less than 10E-06 for
  aircraft datalink systems)

17
ASOR Steps - Mitigate

• Create mitigation strategies and apply to system
  elements and stakeholders (for example, data
  error control to be applied to avionics, ground
  networks as appropriate. Note multiple mitigation
  opportunities in DO-264 E.3.2 (7))