The Safety Continuum – A Doctrine for Application

Prepared by: The Standards Management Team, AIR

Date: September 2014
INTRODUCTION

Beginning in 2012, the Aircraft Certification Service (AIR) began a conscious effort to increase 

awareness of the safety continuum amongst all Aircraft Certification employees. An increase in 

awareness is critical to achieving the next level of product safety. The safety continuum is a 

fundamental element of the AIR: 2018 Vision.

Title 49 USC, Chapter 447, Sec 44701 (the Act) provides a clear direction to the FAA as it relates 

to the continuum:

When prescribing a regulation or standard under subsection (a) or (b) of this section or 

any of sections 44702-44716 of this title, the Administrator shall – (1) consider – (A) –

the duty of an air carrier to provide service with the highest possible degree of safety in 

the public interest; and (B) differences between air transportation and other air 

commerce [emphasis added];...

The United States Congress laid the foundation for the safety continuum when they 

authorized/established the FAA. No attempt is made at a quantifiable definition. Instead, the 

FAA is encouraged to recognize that not all aircraft or aeronautical products are the same. 

Therefore, they should not be viewed in the same light or treated in the exact same manner. 

DOCTRINE

As a service, AIR will balance the needs of our applicants, aircraft owners and operators with 

the public’s demand for safety assurance. By constantly reaching this balance, we can continue 

to see the safety of aviation grow as we allow for the proper introduction and oversight of 

safety enhancing technologies.

AIR will establish standards, policy and oversight that are adaptable over a broad range of 

aircraft types and operations to achieve the next level of safety in a manner that is acceptable 

to public interest and air commerce. Failure to do so will result in an inadvertent decrease in 

safety by preventing safety improvements and stifiling technological innovations that can 

enhance safety.

DISCUSSION

Proper execution of the safety continuum leads to a balance between safety and societal 

burden. While too little safety oversight is a clear threat to safety, too much rigor can prove to 

be an equal threat. As a service, AIR will balance the needs of our applicants, aircraft owners 

and operators with the public’s demand for safety risk management and safety assurance. By 

constantly reaching for this balance, we can continue to see the safety of aviation grow through

the proper introduction and oversight of safety enhancing technologies.

The philosophy of the Safety Continuum must be shared equally across the multiple products 

the FAA oversees (airplanes/engines/propellers/parts/appliances, etc). However, the Safety 
Continuum does not demand a singular application across these products. Rather, each office

or directorate should tailor the continuum consistent with their product of responsibility. 

This tailoring should consider the intended use and operation of the product and the product’s 

acceptable level of risk to the general public. This tailoring applies not only to the certification 

requirements established by each office or directorate, but also the regulatory model those 

entities choose to adopt. To be certain, the continuum focuses on establishing the proper level 

of certitude within the regulations/requirements. Once these are established, the applicant is 

expected to demonstrate compliance to all applicable regulations/requirements. 

There is no closed algebraic expression for describing the continuum. The continuum is 

dependent upon multiple variables, including engineering judgment. To satisfy our 

Congressional mandate, AIR employees must recognize the following:

Level of Safety may be a function of complexity and performance, number of passengers, risk

to people and property on the ground, risk assumed by the pilot/flight crew, risk assumed by 

the passenger(s), engineering judgment...this is not an exclusive list; other variables will affect 

the proper level of safety.

As described in Figure 1, society demands greater safety assurance as the type of vehicles and 

their operations become more complex, and as the occupants become further removed from 

understanding and managing the risks. That is, society demands a greater safety rigor for a 

transport airplane versus a 2 or 4 place general aviation aircraft. 

Figure 1, Safety Continuum and Societal Expectations
The FAA meets that demand in several ways including:

• Rigorous design standards in 14 CFR part 25

• Generally less rigorous but safe standards in 14 CFR part 23

• Differences between the operational rules of 14 CFR parts 91 and 121*

• Differences in flight crew qualifications, training and medical certification requirements

• Mandatory service difficulty reporting in 14 CFR 121*

* Safety is not achieved solely through certification standards. 

The design, introduction, use and continued operational safety of an aircraft can be considered

a “system.” If AIR does not exercise safety oversight commensurate with the risk, there will be 

an inadvertant decrease to the safety of the system. Safety critical items “escape” and the rate

of fatal accidents might increase. In Figure 2, this is shown on the left slide of the graph.

Equally challenging, however, is applying too much rigor, shown on the right side of the 

graph. If certifcation requirements and oversight are overly stringent, safety can be 

jeopardized because the burden of certification will prevent the adoption of safety enhancing 

technologies. 

Figure 2, Safety Continuum Application
A balanced approach allows the FAA to meet and/or increase safety objectives while imposing 

the least burden on industry and society. This is shown in the green shaded area in the Figure 

above.