by Senior First Officer Cristiano Di Murro
The objective of aviation safety management systems is to
1. Proactively manage safety,
2. Identify and report potential safety hazards,
3. Determine risk to operational safety; and
4. Implement risk controls to mitigate identified risk.
When an aviation service provider evaluates their risk to operational safety,
they have to ask themselves a very pointed, and sometimes uncomfortable
question: “What is our risk appetite?”
The term Acceptable defines an aviation service provider’s minimum level of
acceptable risk for a given safety issue. “Acceptable” describes the need for
no further mitigatory actions on the part of the service provider for the safety
concern in question. This determination will be made based on the
probability and severity of the evaluated safety concern.
Why Is Acceptable Level of Safety Subjective?
Absolute safety is an impossible goal, yet service providers need to be able
to set standards for how much risk is admissible. ALoS is the response to
this dilemma. Because of this, ALoS is “exclusively concerned with safety
performance measurement”.
What this means is that, in terms of safety performance, ALoS marks the
point at which, for any given hazard or potential mishap:
-The current level of safety performance remains “good enough”;
-Risk control measures needed to further increase the safety margin for the
hazard/mishap would be unreasonable/unrealistic to implement; and
-Risk controls are effective enough that the residual risk is willingly taken on
by the service provider.
It’s important to note that while defining a level of acceptable safety is a
requirement for providers, it’s up to each provider to establish just what is
and what isn’t acceptable. In this way, service providers define their ALoS,
and then show (e.g., with safety data), that they operating within an
acceptable range of risk.
Acceptable Level of Safety is subjective and can change as the environment
changes. As an operator becomes more successful and attracts more
clients, this operator may become emboldened and increase their risk
appetite. When one considers an inverse economic scenario, an operator
may determine that their ALoS is too aggressive and that they need to either:
-Adjust their exposure to particularly risky hazards; or
-Adjust operational processes to reduce risk by implementing supplemental
control measures.
Relationship between Risk Matrix and Acceptable Level of Safety
The Risk Matrix is the backbone of ALoS in terms of:
-Drawing line between acceptability/unacceptability;
-Ensuring consistent assessment of acceptable and not acceptable risk;
-Setting benchmarks for residual assessments of allowed exposure; and
-Determining organizational authority level required to accept identified risk.
During the early stages of an aviation SMS’ risk management process,
service providers use initial risk assessments from reported safety issues
and audit findings to decide whether or not the evaluated concern meets the
criteria for acceptable risk. For example, an organization might define
acceptability as any risk assessment that is:
-“Green,” low-risk issues, and all other risk assessments requiring further
mitigatory action;
-“Yellow” or “green” (medium or low) risk issues, with only high-risk issues
requiring further action; or
-Medium-low issues, where the risk assessment is on the lower “half” of the
risk matrix.
The reason there is a variance between aviation service providers is either:
Differing willingness to take on more risk as being acceptable (risk appetite);
and Different defining criteria for either probability or severity.
ALoS absolutely requires very clear criteria for probability and severity in
order to have consistent risk assessments across the life span of the
implemented SMS.
Complex operators may have more than one risk matrix in their aviation
SMS. Each risk matrix will be used to risk assess safety concerns for their
specific division, whether the “division” is:
-Functional (flight ops, maintenance, engineering, ground side, etc); or
-Geographical region (North America, Middle East, Africa).
While some aviation service providers have distinct risk matrices for each
division, the general rule of thumb is to use the same risk matrix across the
entire company. While this is not required, it is certainly a best practice as it
increases consistency and reduces ambiguity and confusion among the
managers who have to review reports based on risk assessments.
Risk matrix criteria are simply the tangible “markers” of a particular level of
severity/probability. For example, you might define specific criteria for a level
of severity based on:
-Financial loss;
-Damage to equipment; Injury/loss of life;
-Effects on operations; and Environmental damages.
The more criteria listed for each level of severity the better. Next, you might
define specific criteria for a level of probability based on:
-Number of times occurred in company/industry in the past; or
-Rate per number of flight operations expected in the future (such as on
occurrence in 100k operations, however, you define operations) given
existing conditions and controls.
Establishing an Acceptable Level of Safety
Operators should create their risk matrix criteria, and decide which
combination of severity likelihood is the minimum requirement for
acceptance. Best practices for creating a risk matrix that is swiftly being
adopted is to color code cells and maybe labels as:
-Low-risk items as green, indicating “acceptable;”
-All medium risk issues (if applicable) in yellow indicating “acceptable with
mitigation measures;”
-Higher grade medium risk issues (if applicable) in orange, also indicating
“acceptable with mitigation measures;” and
-Unacceptable risk will be red.
Final Thought Justifying Criteria for ALoS in Aviation Industry
As discussed, you need to justify your established criteria for the level of
acceptable risk. Justifying risk matrix criteria involves using:
-Safety performance indicators; and
-Safety performance targets.
Safety targets and key performance indicators are composed using:
-Organizational safety goals and objectives;
-Safety initiatives and feedback originating from the civil aviation authority
(CAA); Safety data, such as from an aviation safety database;
-Safety charts and metrics; and
-Demonstration of “acceptable” issue safety performance.
A good way to begin this process is to review:
-Key performance indicators (KPIs) related to risk assessments;
Leading indicators related to risk assessments; or
-Custom graphs that show hazard classifications based on risk
assessments.