The European Aviation Safety Agency (EASA) is expected to brief member states in June on its rulemaking permitting commercial single-engine turbine operations in instrument meteorological conditions (SET-IMC), keeping the rule on pace for release next year. The EASA anticipates releasing an opinion on the rulemaking in September, clearing it for European Commission consideration. Finalization is anticipated in next year’s first half, if all goes as planned, said Jens Hennig, vice president of operations for the General Aviation Manufacturers Association and a participant on the commercial SET-IMC rulemaking committee.

Developed in concert with the government-industry rulemaking committee, the NPA drew on more than two decades of debate about and research into the use of single-engine aircraft in commercial operations, beginning with a study by the Joint Aviation Authorities in 1991. The EASA released the commercial SET-IMC proposal, NPA 2014-18, in July last year, and the rulemaking committee finished its review of 150 comments on the proposal in March.

While most of the comments were in favor of proceeding with the rulemaking, German authorities, long wary of SET-IMC operations, remain opposed. Also expressing concerns were officials from the UK and the Netherlands. Like Germany, the UK has had long-standing concerns about SET-IMC. But in recent years, the officials moved away from philosophical opposition to more technical questions. Questions from the Netherlands, like those from the UK, were technical in nature, said Hennig, who stood in as chairman at the final rulemaking review.

Commercial single-engine operations have been authorized for decades in the U.S. and are in place in other countries, Canada and Australia among them. A handful of European nations have approved special exemptions for commercial SET-IMC operations, and currently 12 aircraft are flying under those exemptions.

The EASA proposal would standardize the requirements, although operators would still need special authorization. The EASA proposal limits the commercial operations to turbine aircraft; in the U.S. single-engine piston aircraft are permitted to fly commercially in IFR.

The European rule imposes equipment requirements that match standards released by the International Civil Aviation Organization in the mid-2000s. Since the U.S. “SEIFR” (single-engine [commercial] IFR) rule predated those standards, no such equipment requirements apply.

Industry Concerns Addressed

The rulemaking committee also hoped to address key concerns by building into the proposal a risk-based approach, requiring substantial flight planning for SET-IMC operations to ensure that “at every step along the route the aircraft can safely glide to the ground in the event of loss of engine power,” Hennig said.

During its final review of the comments, the committee debated a number of other issues, including whether two pilots should be mandated for commercial SET-IMC operations. Proponents believe such a requirement would provide another layer of safety, but committee members argued that all the aircraft involved have been certified for single-pilot operation. 

Another issue under discussion surrounded a requirement for full-flight simulator training. Committee members, however, recognized that simulator training is not available in all locations and instead recommended that pilots be encouraged to receive simulator training when possible. That issue, Hennig added, was recognized as a larger debate for all operations. Committee members did not believe that single-engine aircraft should be treated differently for the purposes of the SET-IMC rule.

The committee further discussed which data to use for the underlying safety basis. Some committee members preferred the use of European-specific data, but others noted SET-IMC operations are so limited in Europe that there hasn’t been enough data developed and pushed for use of global data. The committee reviewed a handful of other issues ranging from takeoff minimums to equipment requirements. Pratt & Whitney Canada, which participated in the rulemaking committee, had furnished data based on millions of hours of its turboprop engines commonly used in single-engine operations.

In the U.S., approximately 670 single-engine aircraft are used in commercial SEIFR operations. While 12 of the aircraft are currently in operation in Europe, single-turbine manufacturers have long eyed the potential for a commercial market there. In Europe officials see a benefit particularly for cargo carriage, enabling access to remote regions that otherwise could not be served in a timely fashion, noted Hennig.