A rating system that assesses the benefits of safety equipment could incentivize helicopter operators to add the equipment even in the absence of regulatory mandates, according to a report published by the Vertical Aviation Safety Team (VAST). The VAST Rotorcraft Safety Rating Concept Special Working Group created the “Investigation of a Rotorcraft Safety Rating Concept” report.

The safety rating concept is gaining new interest, partly because the International Helicopter Safety Team established in 2005 hasn’t seen the same accident reduction success as the Commercial Aircraft Safety Team, which achieved a more than 80% reduction in fatalities in 10 years among U.S. airlines. According to the report, “The IHST effort did not have the same results, and the 80% target was not reached. The IHST efforts continued past the original 10-year mandate and a slow, continuous decrease in the accident rate has been noted over the years.”

A rating system is not a new idea and was considered by EASA, then later the International Oil and Gas Producers-Aviation Sub Committee and HeliOffshore. The FAA proposed ratings for rotorcraft design and equipment in 2020. “The establishment of the Vertical Aviation Safety Team (VAST) in 2021 facilitated the opportunity to create a dedicated working group to study a proof of concept for a helicopter safety rating scheme,” according to the working group.

There are significant challenges to developing and implementing a rating system for helicopters, and the working group contrasted new car assessment programs (NCAP) with a helicopter rating system that would have to address products that last for 40 to 50 years, across multiple generations. Cars have a much shorter life cycle, although the working group’s claim that this ranges from three to six years may be inaccurate. IHS Markit estimates average age of U.S. vehicles at 11.6 years.

The car-helicopter comparison is also weakened because of their different operating environments. “Cars are driven on highways that are relatively homogeneous. Helicopters are flown in a wide variety of missions, in vastly differing conditions, with differing equipment installed,” according to the working group. “Rating a helicopter and any subsequent comparison thus requires knowledge of the mission, conditions, equipment, etc.”

Helicopters are certified under two sets of regulations, Part 27 for lighter machines and Part 29 for larger, more complex rotorcraft. This could require two separate rating systems.

There is also an implicit bias toward new aircraft, according to the working group, and this assumes that newer aircraft are safer. But this might not be the case since there could be unknown problems that aren’t revealed until a new aircraft operates in the field. Older aircraft have proven their reliability, and it doesn’t make sense to automatically rate them lower than new aircraft.

Looking at automotive rating systems, the working group pointed out that the U.S. National Highway Traffic Safety Administration introduced its 5-Star rating system in 2010, but the overall vehicle score isn’t impacted by available advanced safety technologies. The European NCAP, however, does take into account safety-assist features and thus “shows good correlation” for a helicopter rating system. Yet, the working group explained, “The analysis of real-world fleet helicopter experience has yet to prove out the proposed helicopter rating system.”

The overall benefit of a rating system would be to drive safety improvements in helicopters, both old and new. “A simple, transparent rating system would benefit operators/owners as they could easily identify those features that could be added to their current fleet to increase overall safety. And, if the insurance industry were to participate, it may also help decrease insurance costs.” 

An interesting aspect of the working group’s efforts is the focus on technical factors as opportunities for safety improvements, without considering human error, which is the predominant cause of helicopter accidents.

Human factors expert Doug Shappell addressed this question, highlighting the fact that it is possible to design aircraft and their systems to take into account human behavior and decision-making, to reduce “the likelihood of human errors or [reduce] the accident severity if the system fails to prevent the error from occurring,” according to the working group.

“Human error is inevitable, but by understanding human factors, we can design systems that reduce the likelihood of errors and improve safety in aviation,” Shappell explained.

“This project utilized accident data to identify those systems that would directly counter the most prolific causal factors,” the working group added, “and introduce those systems and propose a concept for measuring potential derived benefits.”

To categorize accident types that could benefit from enhanced technologies that would help prevent accidents or improve occupant survivability, the working group chose two higher-level accident categories that reduced the complexity of the accident-type analysis: loss of control and collisions.

The five helicopter OEMs that participated in the working group provided statistics that showed loss of control accounting for 27% of accidents and collisions another 27%. “There was some variation from one OEM to another in percentages, but the overarching theme was that loss of control and collisions together accounted for at least 50% of accidents for four out of the five OEMs. This assessment gave the working group an assurance that a safety rating prototype could have the most impact if it focused on enhanced technologies installed on the helicopter that could potentially change the outcomes of accidents due to loss of control and collisions.”

Loss of control includes: unintended flight into IMC and low-visibility scenarios; vortex ring state; turbulence; and handling deficiencies. Collisions include midair collisions with aircraft or wildlife; wire strikes; and striking other objects.

The selected technologies to be rated need to help prevent the above or with survivability if an accident occurs due to the above causes. They must have a supplemental type certificate and also be available for retrofit or new aircraft installation.

The working group showed examples of potential ratings that include weighting factors that favor certain types of added equipment. For example, an autopilot is weighted higher for loss of control prevention than a data collection system. The types of equipment and ratings also recognize the mission and what that mission requires. It doesn’t make sense to rate the benefits of floats for a helicopter that flies only over land.

For now, the rating scheme “is offered as a proof of concept for further validation tailored to the unique requirements of various industry stakeholders,” according to the working group. “While several project participants tested the proposed safety rating scheme extensively in representative use cases, further testing and validation by OEMs, operators, and key stakeholders is essential.

“The use of a rating system in the rotorcraft industry may be an extremely challenging but viable option. The process and effort to create this independent organization would require careful evaluation by the VAST and stakeholder organizations. The rotorcraft industry simply cannot test, certify, and integrate emerging technologies at the rapid pace routinely demonstrated in the automobile industry. The pace of integration and certification will, however, enable careful consideration of newly introduced safety technologies in future versions of a rotorcraft safety rating.”

The working group acknowledged that it hasn’t considered who might administer the rating scheme, although it should be an independent entity. “There is potential for an industry group or the insurance industry to provide that function.”

According to the working group, “The safety rating is at a proof-of-concept stage.” While it starts with addressing the needs of light helicopters as their accident rate is the highest, it should eventually address medium and heavy helicopters and multi-mission operations.