More than 15 years after the publication of initial proposals, commercial single-engine operations under instrument meteorological conditions (SE-IMC) could at long last become permitted in Europe, though not before  2010.

The European Aviation Safety Agency (EASA) expects soon to commission a study that would spell out the rules and requirements for such operations. The agency foresees establishment of related airworthiness regulations about three years from now.

An EASA spokesman told NBAA Convention News that results from its contracted study could come by the end of next year. “Then an opinion introducing SE-IMC operations in commercial air transport could be [expected] at the end of 2009,” he predicted.

Charged with establishing a single system of region-wide airworthiness and operations regulations, the EASA has inherited the unfinished business from the former European Joint Aviation Authorities (JAA), a group permitted to set but not enforce standards since national aviation authorities were expected to apply local rules under exemption.

SE-IMC proponents had hoped to see JAA approval, but after exhaustive efforts, a draft final rule [promulgated under NPA OPs 29, a notice of proposed amendment to basic JAA fixed-wing operations requirements (JAR-OPs 1)] failed to receive sufficient support from the national authorities making up the JAA committee in charge of the effort.

The committee stopped SE-IMC work earlier this year, and the JAA SE-IMC working group that generated myriad draft proposals is now in limbo. The EASA said the JAA “did not finalize its position” on SE-IMC operations. Accordingly, it would take the issue “on board in the context of the extension of [EASA’s] scope of responsibilities,” the agency wrote.

EASA is not yet in charge f operations rulemaking, for which its implementing rules remain to be established, but said it would “take into account” the standards and recommended practices of the International Civil Aviation Organization (ICAO), which permits SE-IMC operations. Once airworthiness responsibility is extended to include operations late next year or in early 2008, the EASA would be able to notify ICAO of any rule difference–as, for example, the UK Civil Aviation Authority previously did when it declined to approve such flights.

Current European regulations prohibit public-transport SE-IMC, except under special visual flight rules clearance. SE-IMC operations are approved in flight-information regions around Denmark and Greenland. Finland and Norway permit both passenger and freight services, while France, Spain and Sweden approve cargo-only flights. Switzerland allows passenger and cargo services by Swiss companies flying Swiss-registered aircraft in Swiss airspace.

During promulgation, initially conservative NPA OPs 29 proposals were eased with the introduction of so-called “risk periods.” While allowing for some restricted flight over water or inhospitable terrain, early proposals had required flights always to be within reach of a landing site should power be lost. Subsequently, NPA OPs 29 allowed a maximum time during which flights could be out of still-air gliding range of a landing site, with multiple risk periods permitted (up to a cumulative 15 minutes per flight).

The draft included requirements for systems and equipment enhancements and more comprehensive experience and training of pilots. Engine-reliability proposals specified that power loss, such that a forced landing becomes inevitable, should occur less than once in 100,000 hours.

(Unlike commercial aviation, general aviation typically measures safety in terms of risk compared with duration of flight rather than number of events, implying that all phases of flight are equally safe: several flights within one hour are perceived as rendering no greater risk-exposure than a single 60-minute period.)

The Single Engine Turbine Alliance (SETA)–an SE-IMC lobbying group established by Cessna, Piper, Pilatus and Socata, and represented by former JAA secretary-general (and UK aviation safety regulation director) Ron Ashford and ex-U.S. FAA Administrator Langhorne Bond–has highlighted related safety data. Considering statistics for Cessna Caravan, Socata TBM 700 and PC-12 operations, the alliance identified 21 fatal accidents from 1991 through March of last year.

The survey period involved 4.93 million hours of commercial operations with those types in Western nations having “standards equivalent to those to be expected in JAA countries,” equivalent to 4.26 fatal accidents per one million hours, said SETA. Comparable overall turboprop fatal-accident rates ranged between 2.4 per one million hours (worldwide Twin Otter scheduled operations) and 19.3 per one million hours (UK turboprop airline operations). The SE-IMC working group found this met JAA requirements for single-engine turboprop performance and was as good as the performance of comparable light twins, said Ashford.

Nevertheless, some EASA countries–notably Germany, Italy and the UK–remain unconvinced about SE-IMC safety. Some of their major reservations include:

• the concept of two-minute takeoff and 15-minute cruise “risk periods,” as well as specifications of and requirements for availability and physical inspections of “landing sites,” offers insufficient levels of safety;

• approval for SE-IMC flights over densely populated areas may be politically unsustainable;

• non-European SE-IMC safety data do not read across to European population and airfield environments and rely on a single aircraft type not considered typical for likely European operations; and

• the parties that constituted JAA NPA working groups were not sufficiently balanced or independent.

Meanwhile, the safety agency does not expect SE-IMC approval to be made easier by any harmonization of FAA and EASA regulations, which are “quite different. A full harmonization is not foreseen,” according to the spokesman.