Operators pushing for clearance to fly commercial single-engine flights in IFR conditions, which are not allowed under European Union (EU) legislation, will be encouraged that regulators have brought forward by a year the start and end dates for rulemaking. That is the good news. The bad news–almost 25 years after the initial proposals–is that it will be well after the middle of this decade before regulations could permit such operations.

Formal consideration of single-engine commercial air transport inIMC or at night (SE-IMC/night, equivalent to U.S. single-engine IFR, appears in the 2011-14 European Aviation Safety Agency (EASA) rulemaking program. This shows that development of implementing rules (IR) for airworthiness and operational approval for SE-IMC/night flying is scheduled to begin early next year, assuming that budget and resources are available. It should lead to an EASA “opinion” on proposals in four years’ time. [In European legislative procedures, opinions are draft rules sent to the European Commission for further processing before enactment. New laws are proposed as amendments to the IRs covering a basic regulation; in this case, that covering commercial air transport.–Ed.]

A year after the opinion is issued, guidance materials should appear in the first quarter of 2016 to support a formal EASA recommendation to the European Commission (EC), assuming regulatory priorities have not changed. But the industry will not be holding its collective breath, having long grown used to such changes. Eighteen months ago it was reported at the U.S. NBAA Convention that European approval for commercial single-engine flights could be recommended during 2014–and that only after years of earlier delay.

Under so-called “derogation” principles that permit EU member states to deviate from overall regulations, several countries–including Finland, France, Greece, Norway and Spain–have permitted domestic commercial SE-IMC flights by air-operator’s certificate holders carrying only cargo under specific circumstances. Globally, the International Civil Aviation Organization has issued appropriate operating standards. After several years of discussion, the European Joint Aviation Authorities (JAA)–EASA’s predecessor–failed to establish a consensus among the region’s national aviation authorities (NAAs).

Commercial SE-IMC/night flights might have been possible from last year had EASA accepted and adopted JAA safety data, but officials did not consider information included in data from outside Europe to be representative of European operating conditions. EASA had said in 2008 that SE-IMC/night work would require separate rulemaking after its “opinion” on the EASA operations IR. It was thought then that SE-IMC/night operations could be included with other changes in an expected first amendment to EASA ops legislation in 2010/11.

Individual European NAAs have taken differing views on the safety of commercial SE-IMC/night operations over the years. Some have allowed flights while applying conditions; others have resisted any temptation to allow fare-paying travelers to be exposed to the total loss of thrust that would follow an engine failure. In 2007, EASA set up an independent assessment that aimed “to identify the risks and possible mitigating factors [to assure] that SE-IMC operations do not involve more risks than multi-engine IMC operations.”

Conducted by consultants Qinetiq, that study concluded that accident rates involving fatal SE-IMC/night events from all causes should be “more remote than 4 x 10-6/flight hour (fh),” a performance slightly better than twin-engine safety in comparable categories. Qinetiq also concluded that fatal SE-IMC/night engine-failure rates should be less than 1.3 x 10-6/fh and made recommendations on aircraft-certification testing, training and the need for a second flight-crew member.

The report offered a theoretical risk assessment that, depending on “realistic assumptions,” concluded there was a hypothetical possibility that the target engine-failure fatal accident rate could be shown to be achievable. Permitted SE-IMC/night operations would need to be covered by “appropriate limitations on cloud ceiling and visibility, [operations] from and to suitable airfields, [and on] duration of risk periods when no landing site is within gliding range.”