Possibilities are variables while probabilities are facts. Probabilities vary due to the effect of possibilities. A possibility is often applied to safety as a fact with an undisputed path for an event to occur. Possibility is the expression of a desire for an event to occur, while probability is an analysis of facts to establish a likelihood level of an event to occur. When possibilities are applied to regulatory compliance operations gradually become a system failure, or a dysfunctional operation, while with the application of probabilities the operations improves their safety, or functional systems and operates with an effective SMS.
There is a possibility that all marbles remain in the bowl, but a low probability.
There is only one possibility applied, but this possibility is applied to the different criteria of likelihood. Likelihood is defined in many shapes and forms. One method is to define the likelihood of ten independent levels based on a time-frame between events.
Likelihood levels could be defined as follows:
• Times between intervals are imaginary, theoretical, virtual, or fictional.
• Times between intervals are beyond factors applied for calculation of problem-solving in operation.
• Times between intervals are separated by breaks, or spaced greater than normal operations could foresee.
• Times between intervals are without definite aim, direction, rule, or method.
• Times between intervals are indefinable.
• Times between intervals are inconstant.
• Times between intervals are protracted and infrequent.
• Times between intervals are reliable and dependable.
• Times between intervals are short, constant and dependable.
• Times between intervals are methodical, planned and dependable, without defining the operational system or processes involved.
When applying examples to these likelihood levels they become alive and practical in a Safety Management System.
The likelihood is inconceivable.
D) Randomly – an engine failure just after liftoff occurs randomly. These intervals between engine failures are without definite aim, direction, rule, or method.
However, when an engine failure is applied as a possibility only, it becomes a possibility to an inconceivable event and there could not be safety in aircraft operations.
The same scenario holds water when applying one possibility to regulatory compliance. It could be said, and it has been said that there is a possibility for an operator to be non-compliant with one regulation and therefore a regulatory non-compliance finding could be issued. When applying one possibility without a link to likelihood all operations are non-conforming to regulatory requirements and all operations becomes non-conforming to safety.