top of page
  • Donna Shope

Measuring Safety Performance in Airworthiness

The Wright Brothers and their mechanic, Charles Taylor, had a dream only achieved by persistence, trial, and error.  Their confidence and determination to learn and improve upon design flaws assisted them with measuring the performance of and, eventually, the success of powered flight.


In the past 100 years, there has been significant improvement in the reliability of aircraft parts and material manufacturing with an immense increase in technology, automation, and the enhancement of safety and oversight.  Industry engineering objectives have been striving for perfection, creating lighter and stronger materials, more aerodynamic and energy-efficient designs, and greater product resiliency.  However, the “Human Factor” will always have imperfections.



In the early days of flight, approximately 80 percent of accidents were caused by the machine, and 20 percent were caused by human error. Today, that statistic has reversed. Approximately 80 percent of airplane accidents are due to human error (pilots, air traffic controllers, mechanics, etc.), and 20 percent are due to machine (equipment) failures. ( / Aero_Q207)

Measuring Safety Performance

Safety performance is a comprehensive approach critical to ensuring the safety of individuals and processes within industries. It encompasses data collection, assessment, monitoring, improvement efforts, and a commitment to continuous learning and adaptation to create and maintain a safe working environment.  Organizations can cultivate a mature safety culture by continually monitoring, learning, adapting, and improving safety practices.


Safety Performance Indicators (SPIs) 

Performance Indicators are measurable data or metrics organizations use to assess and track their safety performance. These indicators provide insight into the effectiveness of safety management systems and help identify improvement areas. Safety Performance Indicators play a vital role in this process and are categorized as Leading (Proactive) and and Lagging (Reactive) Indicators:

  1. Lagging Indicators (Reactive):

Lagging indicators are retrospective measures that assess safety performance based on past incidents and accidents. These indicators help organizations understand what went wrong and can include metrics such as injury rates, accident frequency, and property damage costs. Key points to note about lagging indicators:


  • They focus on historical data and incidents.

  • They are typically used to evaluate the outcomes of safety programs.

  • They help identify where safety improvements are needed based on past performance.

2. Leading Indicators (Proactive):

Leading indicators are forward-looking measures that assist organizations in predicting and preventing safety issues before they result in high-consequence events or incidents. They provide insights into safety performance and the effectiveness of preventive measures. Leading indicators can include metrics such as near-miss reporting, safety training participation, and safety compliance audits. Key points to note about leading indicators:


  • They focus on activities and behaviors that reduce risks and prevent incidents.

  • They help identify potential safety issues and areas that require intervention.

  • They promote a proactive safety culture and encourage preventive actions.


The distinction between lagging and leading indicators is crucial for a comprehensive safety performance measurement system:


  • Lagging indicators are essential for understanding the impact of safety incidents and accidents. They can help organizations learn from past mistakes and adjust safety strategies accordingly.

  • Leading indicators are critical for identifying and addressing potential risks before they escalate into major incidents. They enable organizations to prevent accidents and improve safety performance proactively.

Almost all SPIs can be attributed to “Human Error.”  Even a mechanical/material failure such as corrosion, erosion, fatigue, or overload could be investigated by the Root Cause Analysis (RCA) process and possibly determined to be human-initiated.


Attempting to monitor numerous SPIs will create substantial data. However, defining the meaning and indication of copious data will likely create confusion.   Define and monitor the SPIs with the most significant potential for incidents or accidents relevant to the complexity or size of the organization and reassess periodically for any changes in processes, technology, or organizational goals. 

We had an issue and corrected the problem.

Periodically review:  Did the “fix” rectify the situation or create a new issue?


Monitoring Safety Performance

Performance Monitoring is vital to risk management, process improvement, and overall organizational effectiveness.  A comprehensive hazard identification will facilitate a thorough understanding of the threats and risks and assist in identifying areas where performance is falling short of expectations or standards.  Using metrics with established alert levels, usually lagging indicators, will provide the ability to track and evaluate the performance of various elements within an organization, including risk controls, process outputs, and human behavior.  When monitoring SPIs, alert levels reflect indications of nonconformities, giving meaning to the measurement and driving corrective actions.  The primary goal of performance monitoring is to provide adequate attention and take appropriate steps to address any safety issues.  Management guru Peter Drucker once said, “[only] what gets measured, gets managed.”


Example Airworthiness SPI topics to consider:

* The number one Causation of Aviation Mishaps by Maintenance (Omissions)

Procedural Noncompliance

Failure to Follow Procedures (FFP) is not following prescribed procedures to complete a task.  The omission of a maintenance procedure, step, or task is an error or failure to do the right thing and can lead to a maintenance-related safety event.  Improper recording or documenting of maintenance could also lead to a safety event.  Procedural Noncompliance addresses the issues of why there was a failure to follow procedures and the possibility that unclear standards, inadequate training, or leadership failures could have been contributing factors.  Implying that the omission of an act is based primarily on ignorance, whereas the commission of an action is based more on malice.  The adage is: “If you don't have time to do it right, when will you have time to do it over?” (John Wooden)

In the past, when an employee made a significant mistake, they got “the Hammer” or were fired, and a different employee started doing the job.  “In the 5 elements of Human and Organizational Performance (H.O.P.), the 1st two elements are: 1) People make mistakes, and 2) Blame fixes nothing.”  We have since learned that we didn’t fix the problem.  The mistake was made, and the response was reactive, but we didn’t investigate “why” the employee made the mistake initially.  Was it a lack of training?  Was the employee distracted, fatigued, or complacent?

Safety management systems are crucial for ensuring workplace safety, but we must not overlook the human element. Concentrating heavily on the SMS system and fixating on the components and elements is only half the concept.  Employees are the ultimate reason safety programs exist, and their behaviors, decisions, and attitudes play a significant role in the success of these systems.

What’s in YOUR toolbox?

How do you measure Safety Performance?     


Conklin, T. (2019). The 5 principles of human performance: A contemporary update of the building blocks of human performance for the new view of safety. Pre-Accident Investigation Media.

International Business Aviation Council (IBAC), Measuring Safety Performance PowerPoint (Date Unknown)

Klaus, P. (2015). The Devil Is in the Details – Only What Get Measured Gets Managed. In: Measuring Customer Experience. Palgrave Macmillan, London.

NavalSafetyCommand (2020) MECH – Fall Winter 2020 – Vol. 65, No 2.

Starke, J.  (2022) ‘Season 1 Episode 7, A Look at Human and Organizational Performance’, Baldwin Safety & Compliance Safety Chat Podcast, March 14, (September 13, 2023).



bottom of page